Monogenic causes of autoimmunity provide key insights into the complex regulation of the immune system. We report a new monogenic cause of autoimmunity resulting from de novo germline activating STAT3 mutations in five individuals with a spectrum of early-onset autoimmune disease, including type 1 diabetes. These findings emphasize the critical role of STAT3 in autoimmune disease and contrast with the germline inactivating STAT3 mutations that result in hyper IgE syndrome.

The contribution of cis-regulatory mutations to human disease remains poorly understood. Whole-genome sequencing can identify all noncoding variants, yet the discrimination of causal regulatory mutations represents a formidable challenge. We used epigenomic annotation in human embryonic stem cell (hESC)-derived pancreatic progenitor cells to guide the interpretation of whole-genome sequences from individuals with isolated pancreatic agenesis. This analysis uncovered six different recessive mutations in a previously uncharacterized ~400-bp sequence located 25 kb downstream of PTF1A (encoding pancreas-specific transcription factor 1a) in ten families with pancreatic agenesis. We show that this region acts as a developmental enhancer of PTF1A and that the mutations abolish enhancer activity. These mutations are the most common cause of isolated pancreatic agenesis. Integrating genome sequencing and epigenomic annotation in a disease-relevant cell type can thus uncover new noncoding elements underlying human development and disease.

We recently reported de novo GATA6 mutations as the most common cause of pancreatic agenesis, accounting for 15 of 27 (56%) patients with insulin-treated neonatal diabetes and exocrine pancreatic insufficiency requiring enzyme replacement therapy. We investigated the role of GATA6 mutations in 171 subjects with neonatal diabetes of unknown genetic etiology from a cohort of 795 patients with neonatal diabetes. Mutations in known genes had been confirmed in 624 patients (including 15 GATA6 mutations). Sequencing of the remaining 171 patients identified nine new case subjects (24 of 795, 3%). Pancreatic agenesis was present in 21 case subjects (six new); two patients had permanent neonatal diabetes with no enzyme supplementation and one had transient neonatal diabetes. Four parents with heterozygous GATA6 mutations were diagnosed with diabetes outside the neonatal period (12-46 years). Subclinical exocrine insufficiency was demonstrated by low fecal elastase in three of four diabetic patients who did not receive enzyme supplementation. One parent with a mosaic mutation was not diabetic but had a heart malformation. Extrapancreatic features were observed in all 24 probands and three parents, with congenital heart defects most frequent (83%). Heterozygous GATA6 mutations cause a wide spectrum of diabetes manifestations, ranging from pancreatic agenesis to adult-onset diabetes with subclinical or no exocrine insufficiency.

Aims/hypothesis: Current genetic tests for diagnosing monogenic diabetes rely on selection of the appropriate gene for analysis according to the patient's phenotype. Next-generation sequencing enables the simultaneous analysis of multiple genes in a single test. Our aim was to develop a targeted next-generation sequencing assay to detect mutations in all known MODY and neonatal diabetes genes. Methods: We selected 29 genes in which mutations have been reported to cause neonatal diabetes, MODY, maternally inherited diabetes and deafness (MIDD) or familial partial lipodystrophy (FPLD). An exon-capture assay was designed to include coding regions and splice sites. A total of 114 patient samples were tested - 32 with known mutations and 82 previously tested for MODY (n = 33) or neonatal diabetes (n = 49) but in whom a mutation had not been found. Sequence data were analysed for the presence of base substitutions, small insertions or deletions (indels) and exonic deletions or duplications. Results: in the 32 positive controls we detected all previously identified variants (34 mutations and 36 polymorphisms), including 55 base substitutions, ten small insertions or deletions and five partial/whole gene deletions/duplications. Previously unidentified mutations were found in five patients with MODY (15%) and nine with neonatal diabetes (18%). Most of these patients (12/14) had mutations in genes that had not previously been tested. Conclusions/interpretation: Our novel targeted next-generation sequencing assay provides a highly sensitive method for simultaneous analysis of all monogenic diabetes genes. This single test can detect mutations previously identified by Sanger sequencing or multiplex ligation-dependent probe amplification dosage analysis. The increased number of genes tested led to a higher mutation detection rate. © 2013 the Author(s).

Gene expression is tightly regulated with many genes exhibiting cell-specific silencing when their protein product would disrupt normal cellular function. This silencing is largely controlled by non-coding elements and their disruption might cause human disease. We performed gene-agnostic screening of the non-coding regions to discover new molecular causes of congenital hyperinsulinism. This identified 14 non-coding de novo mutations affecting a 42bp conserved region encompassed by a regulatory. element in intron 2 of Hexokinase 1 (HK1), a pancreatic beta-cell ‘disallowed’ gene. We demonstrated that these mutations resulted in expression of HK1 in the pancreatic beta-cells causing inappropriate insulin secretion and congenital hyperinsulinism. These mutations identify a regulatory region critical for cell-specific silencing. Importantly, this has revealed a new disease mechanism for non-coding mutations that cause inappropriate expression of a disallowed gene.

AbstractObjectiveHyperinsulinaemic hypoglycaemia (HH) can occur in isolation or more rarely feature as part of a syndrome. Screening for mutations in the ‘syndromic HH’ genes is guided by phenotype with genetic testing used to confirm the clinical diagnosis. As HH can be the presenting feature of a syndrome it is possible that mutations will be missed as these genes are not routinely screened in all newly diagnosed individuals. We investigated the frequency of pathogenic variants in syndromic genes in individuals with HH who had not been clinically diagnosed with a syndromic disorder at referral for genetic testing.DesignWe used genome sequencing data to assess the prevalence of mutations in syndromic HH genes in an international cohort of patients with HH of unknown genetic cause.MethodsWe undertook genome sequencing in 82 individuals with HH without a clinical diagnosis of a known syndrome at referral for genetic testing. Within this cohort we searched for the genetic aetiologies causing 20 different syndromes where HH had been reported as a feature.ResultsWe identified a pathogenicKMT2Dvariant in a patient with HH diagnosed at birth, confirming a genetic diagnosis of Kabuki syndrome. Clinical data received following the identification of the mutation highlighted additional features consistent with the genetic diagnosis. Pathogenic variants were not identified in the remainder of the cohort.ConclusionsPathogenic variants in the syndromic HH genes are rare but should be considered in newly diagnosed individuals as HH may be the presenting feature.

AbstractFinding new genetic causes of monogenic diabetes can help to understand development and function of the human pancreas. We aimed to find novel protein–truncating variants causing Maturity–Onset Diabetes of the Young (MODY), a subtype of monogenic diabetes. We used a combination of next–generation sequencing of MODY cases with unknown aetiology along with comparisons to the ExAC database to identify new MODY genes. In the discovery cohort of 36 European patients, we identified two probands with novel RFX6 heterozygous nonsense variants. RFX6 protein truncating variants were enriched in the MODY discovery cohort compared to the European control population within ExAC (odds ratio, OR=131, P=l×l0‐4). We found similar results in non–Finnish European (n=348, OR=43, P=5×l0‐5) and Finnish (n=80, OR=22, P=1×l0‐6) replication cohorts. The overall meta–analysis OR was 34 (P=l×l0‐16). RFX6 heterozygotes had reduced penetrance of diabetes compared to common HNF1A and HNF4A–MODY mutations (27%, 70% and 55% at 25 years of age, respectively). The hyperglycaemia resulted from beta–cell dysfunction and was associated with lower fasting and stimulated gastric inhibitory polypeptide (GIP) levels. Our study demonstrates that heterozygous RFX6 protein truncating variants are associated with MODY with reduced penetrance.

Background
Congenital hyperinsulinism (HI) is characterised by inappropriate insulin secretion despite low blood glucose. Persistent HI is often monogenic, with the majority of cases diagnosed in infancy. Less is known about the contribution of monogenic forms of disease in those presenting in childhood. We investigated the likelihood of finding a genetic cause in childhood-onset HI and explored potential factors leading to the later age at presentation of disease.

Methods
We screened known disease-causing genes in 1848 individuals with HI, referred for genetic testing as part of routine clinical care. Individuals were classified as infancy-onset (when diagnosed with HI

SummaryIdentifying genes linked to extreme phenotypes in humans has the potential to highlight new biological processes fundamental for human development. Here we report the identification of homozygous loss of function variants in the primate-specific gene ZNF808 as a cause of pancreatic agenesis. ZNF808 is a member of the KRAB zinc finger protein (KZFPs) family, a large and rapidly evolving group of epigenetic silencers that target transposable elements. We show that loss of ZNF808 in vitro results in aberrant activation of many transposable elements it normally represses during early pancreas development. This results in inappropriate specification of cell fate with induction of genes associated with liver endoderm and a loss of pancreatic identity. We show that ZNF808 and its transposable element targets play a critical role in cell fate specification during human pancreatic development. This is the first report of loss of a primate-specific gene causing a congenital developmental disease and highlights the essential role of ZNF808 for pancreatic development in humans.

AbstractIdentifying copy number variants (CNVS) can provide diagnoses to patients and provide important biological insights into human health and disease. Current exome and targeted sequencing approaches cannot detect clinically and biologically-relevant CNVs outside their target area. We present SavvyCNV, a tool which uses off-target read data to call CNVs genome-wide. Up to 70% of sequencing reads from exome and targeted sequencing fall outside the targeted regions - SavvyCNV exploits this ‘free data’.We benchmarked SavvyCNV using truth sets generated from genome sequencing data and Multiplex Ligation-dependent Probe Amplification assays. SavvyCNV called CNVs with high precision and recall, outperforming five state-of-the-art CNV callers at calling CNVs genome-wide using off-target or on-target reads from targeted panel and exome sequencing. Furthermore SavvyCNV was able to call previously undetected clinically-relevant CNVs from targeted panel data highlighting the utility of this tool within the diagnostic setting. SavvyCNV is freely available.

Gene expression is tightly regulated, with many genes exhibiting cell-specific silencing when their protein product would disrupt normal cellular function1. This silencing is largely controlled by non-coding elements, and their disruption might cause human disease2. We performed gene-agnostic screening of the non-coding regions to discover new molecular causes of congenital hyperinsulinism. This identified 14 non-coding de novo variants affecting a 42-bp conserved region encompassed by a regulatory element in intron 2 of the hexokinase 1 gene (HK1). HK1 is widely expressed across all tissues except in the liver and pancreatic beta cells and is thus termed a 'disallowed gene' in these specific tissues. We demonstrated that the variants result in a loss of repression of HK1 in pancreatic beta cells, thereby causing insulin secretion and congenital hyperinsulinism. Using epigenomic data accessed from public repositories, we demonstrated that these variants reside within a regulatory region that we determine to be critical for cell-specific silencing. Importantly, this has revealed a disease mechanism for non-coding variants that cause inappropriate expression of a disallowed gene.

Identifying copy number variants (CNVs) can provide diagnoses to patients and provide important biological insights into human health and disease. Current exome and targeted sequencing approaches cannot detect clinically and biologically-relevant CNVs outside their target area. We present SavvyCNV, a tool which uses off-target read data from exome and targeted sequencing data to call germline CNVs genome-wide. Up to 70% of sequencing reads from exome and targeted sequencing fall outside the targeted regions. We have developed a new tool, SavvyCNV, to exploit this ‘free data’ to call CNVs across the genome. We benchmarked SavvyCNV against five state-of-the-art CNV callers using truth sets generated from genome sequencing data and Multiplex Ligation-dependent Probe Amplification assays. SavvyCNV called CNVs with high precision and recall, outperforming the five other tools at calling CNVs genome-wide, using off-target or on-target reads from targeted panel and exome sequencing. We then applied SavvyCNV to clinical samples sequenced using a targeted panel and were able to call previously undetected clinically-relevant CNVs, highlighting the utility of this tool within the diagnostic setting. SavvyCNV outperforms existing tools for calling CNVs from off-target reads. It can call CNVs genome-wide from targeted panel and exome data, increasing the utility and diagnostic yield of these tests. SavvyCNV is freely available at https://github.com/rdemolgen/SavvySuite.

AIMS/HYPOTHESIS: Current clinical guidelines for childhood-onset monogenic diabetes outside infancy are mainly focused on identifying and testing for dominantly inherited, predominantly MODY genes. There are no systematic studies of the recessively inherited causes of monogenic diabetes that are likely to be more common in populations with high rates of consanguinity. We aimed to determine the contribution of recessive causes of monogenic diabetes in paediatric diabetes clinics and to identify clinical criteria by which to select individuals for recessive monogenic diabetes testing. METHODS: We conducted a cross-sectional study of 1093 children from seven paediatric diabetes clinics across Turkey (a population with high rates of consanguinity). We undertook genetic testing of 50 known dominant and recessive causes of monogenic diabetes for 236 children at low risk of type 1 diabetes. As a comparison, we used monogenic diabetes cases from UK paediatric diabetes clinics (a population with low rates of consanguinity). RESULTS: Thirty-four children in the Turkish cohort had monogenic diabetes, equating to a minimal prevalence of 3.1%, similar to that in the UK cohort (p = 0.40). Forty-one per cent (14/34) had autosomal recessive causes in contrast to 1.6% (2/122) in the UK monogenic diabetes cohort (p 10%) assisted the identification of the dominant (all p ≤ 0.0003) but not recessive cases (all p ≥ 0.2) in Turkey. The presence of certain non-autoimmune extra-pancreatic features greatly assisted the identification of recessive (p 

Gene expression is tightly regulated with many genes exhibiting cell-specific silencing when their protein product would disrupt normal cellular function. This silencing is largely controlled by non-coding elements and their disruption might cause human disease. We performed gene-agnostic screening of the non-coding regions to discover new molecular causes of congenital hyperinsulinism. This identified 14 non-coding de novo mutations affecting a 42bp conserved region encompassed by a regulatory element in intron 2 of Hexokinase 1 ( HK1 ), a pancreatic beta-cell disallowed gene. We demonstrated that these mutations resulted in expression of HK1 in the pancreatic beta-cells causing inappropriate insulin secretion and congenital hyperinsulinism. These mutations identify a regulatory region critical for cell-specific silencing. Importantly, this has revealed a new disease mechanism for non-coding mutations that cause inappropriate expression of a disallowed gene.

Objective
Mutations in the KATP channel genes, ABCC8 and KCNJ11, are the most common cause of congenital hyperinsulinism. The diagnosis of KATP-hyperinsulinism is important for the clinical management of the condition. We aimed to determine the clinical features that help to identify KATP-hyperinsulinism at diagnosis.


Design
We studied 761 individuals with KATP-hyperinsulinism and 862 probands with hyperinsulinism of unknown aetiology diagnosed before 6 months of age. All were referred as part of routine clinical care.


Methods
We compared the clinical features of KATP-hyperinsulinism and unknown hyperinsulinism cases. We performed logistic regression and receiver operator characteristic (ROC) analysis to identify the features that predict KATP-hyperinsulinism.


Results
Higher birth weight, diazoxide unresponsiveness and diagnosis in the first week of life were independently associated with KATP-hyperinsulinism (adjusted odds ratio: 4.5 (95% CI: 3.4–5.9), 0.09 (0.06–0.13) and 3.3 (2.0–5.0) respectively). Birth weight and diazoxide unresponsiveness were additive and highly discriminatory for identifying KATP-hyperinsulinism (ROC area under the curve for birth weight 0.80, diazoxide responsiveness 0.77, and together 0.88, 95% CI: 0.85–0.90). In this study, 86% born large for gestation and 78% born appropriate for gestation and who did not respond to diazoxide treatment had KATP-hyperinsulinism. In contrast, of those individuals born small for gestation, none who were diazoxide responsive and only 4% of those who were diazoxide unresponsive had KATP-hyperinsulinism.


Conclusions
Individuals with hyperinsulinism born appropriate or large for gestation and unresponsive to diazoxide treatment are most likely to have an ABCC8 or KCNJ11 mutation. These patients should be prioritised for genetic testing of KATP channel genes.

Background: Polycystic kidney disease with hyperinsulinaemic hypoglycaemia (HIPKD) is a recently described disease caused by a single nucleotide variant, c.-167G>T, in the promoter region of PMM2 (encoding phosphomannomutase 2), either in homozygosity or compound heterozygosity with a pathogenic coding variant in trans. All patients identified so far are of European descent, suggesting a possible founder effect. Methods: We generated high density genotyping data from 11 patients from seven unrelated families, and used this information to identify a common haplotype that included the promoter variant. We estimated the age of the promoter mutation with DMLE+ software, using demographic parameters corresponding to the European population. Results: all patients shared a 0.312 Mb haplotype which was absent in 503 European controls available in the 1000 Genomes Project. The age of this mutation was estimated as 105–110 generations, indicating its occurrence around 600 BC, a time of intense migration, which might explain the presence of the same mutations in Europeans around the globe. Conclusion: the shared unique haplotype among seemingly unrelated patients is consistent with a founder effect in Europeans.

Heterozygous mutations in GCK result in a persistent, mildly raised glucose from birth, but it is usually diagnosed in adulthood as maturity-onset diabetes of the young (MODY), where hyperglycemia is often an incidental finding. The hyperglycemia of GCK-MODY is benign and does not require treatment, but is important to be aware of, particularly in females where it has implications for managing pregnancy. We present three cases of neonatal hyperglycemia resulting from a heterozygous mutation in GCK, illustrating its clinical presentation and evolution in early life. In summary, as with adults, neonatal hyperglycemia is an incidental finding, does not require treatment and has no adverse consequences for health. Neonates and their parents should be referred for genetic testing to confirm the diagnosis, avoid a label of diabetes and enable pregnancy counseling for females found to be affected.

OBJECTIVE: ABCC8 mutations cause neonatal diabetes mellitus that can be transient (TNDM) or, less commonly, permanent (PNDM); ∼90% of individuals can be treated with oral sulfonylureas instead of insulin. Previous studies suggested that people with ABCC8-PNDM require lower sulfonylurea doses and have milder neurological features than those with KCNJ11-PNDM. However, these studies were short-term and included combinations of ABCC8-PNDM and ABCC8-TNDM. We aimed to assess the long-term glycemic and neurological outcomes in sulfonylurea-treated ABCC8-PNDM. RESEARCH DESIGN AND METHODS: We studied all 24 individuals with ABCC8-PNDM diagnosed in the U.K. Italy, France, and U.S. known to transfer from insulin to sulfonylureas before May 2010. Data on glycemic control, sulfonylurea dose, adverse effects including hypoglycemia, and neurological features were analyzed using nonparametric statistical methods. RESULTS: Long-term data were obtained for 21 of 24 individuals (median follow-up 10.0 [range 4.1-13.2] years). Eighteen of 21 remained on sulfonylureas without insulin at the most recent follow-up. Glycemic control improved on sulfonylureas (presulfonylurea vs. 1-year posttransfer HbA1c 7.2% vs. 5.7%, P = 0.0004) and remained excellent long-term (1-year vs. 10-year HbA1c 5.7% vs. 6.5%, P = 0.04), n = 16. Relatively high doses were used (1-year vs. 10-year dose 0.37 vs. 0.25 mg/kg/day glyburide, P = 0.50) without any severe hypoglycemia. Neurological features were reported in 13 of 21 individuals; these improved following sulfonylurea transfer in 7 of 13. The most common features were learning difficulties (52%), developmental delay (48%), and attention deficit hyperactivity disorder (38%). CONCLUSIONS: Sulfonylurea treatment of ABCC8-PNDM results in excellent long-term glycemic control. Overt neurological features frequently occur and may improve with sulfonylureas, supporting early, rapid genetic testing to guide appropriate treatment and neurodevelopmental assessment.

OBJECTIVES: to review the data of infants and children with suspected monogenic diabetes who underwent genetic testing. METHODS: Monogenic diabetes is a rare form of diabetes resulting from mutations in a single gene. It can be caused by dominant as well as recessive modes of inheritance. In a country like Pakistan where interfamily marriages are common the incidence of genetic disorders is increased. As Pakistan a resource-poor country, the diagnosis of insulin-dependent diabetes is often delayed and a genetic diagnosis of monogenic diabetes is extremely difficult. Children with clinical diagnosis of monogenic and syndromic diabates were recruited and blood samples were sent for genetic analysis. RESULTS: One thousand sixty four new cases diagnosed with type 1 diabetes were registered at the National Institute of Child Health, Karachi, in the last 10 years. of these 39 patients were selected for genetic testing who were diagnosed with diabetes/had a sibling diagnosed with diabetes before the age of nine months (n = 27) or had extra pancreatic features ( n= 12). We identified mutations in 18/27 cases diagnosed with diabetes before nine months of age. The most common genetic subtype was WolcottRallison syndrome caused by EIF2AK3 mutations (seven cases). KCNJ11 mutations were identified in two cases, ABCC8mutations were identified in four cases from three families, GCK and INS mutations were each identified in two cases, and one SLC2A2 mutation was identified in one case. A genetic diagnosis was made in 12/12 children from six families with diabetes diagnosed after the age of nine months who had extrapancreatic features. Six patients had genetically confirmed Wolfram syndrome (WFS1), three had thiamine-responsive megaloblastic anemia (SLC19A2) and three were diagnosed with histocytosis lymphadenopathy plus syndrome (SLC29A3). CONCLUSIONS: Genetic testing is essential to confirm a diagnosis of monogenic diabetes which guides clinical management and future counselling. Our study highlights the importance of diagnosing monogenic diabetes in the largely consanguineously-married population of Pakistan.

Despite the central role of chromosomal context in gene transcription, human noncoding DNA variants are generally studied outside of their genomic location. This limits our understanding of disease-causing regulatory variants. INS promoter mutations cause recessive neonatal diabetes. We show that all INS promoter point mutations in 60 patients disrupt a CC dinucleotide, whereas none affect other elements important for episomal promoter function. To model CC mutations, we humanized an ∼3.1-kb region of the mouse Ins2 gene. This recapitulated developmental chromatin states and cell-specific transcription. A CC mutant allele, however, abrogated active chromatin formation during pancreas development. A search for transcription factors acting through this element revealed that another neonatal diabetes gene product, GLIS3, has a pioneer-like ability to derepress INS chromatin, which is hampered by the CC mutation. Our in vivo analysis, therefore, connects two human genetic defects in an essential mechanism for developmental activation of the INS gene.

The data on the congenital hyperinsulinism (CHI) in Asian Indian patients is limited. Diazoxide is often unavailable in India, which poses challenge in managing CHI. The study was aimed to present our experience with CHI with a special focus on the effectiveness and cost-effectiveness of octreotide long-acting release (OCT-LAR) among diazoxide-responsive CHI. The data of 14 index cases with CHI registered at our center were retrospectively analyzed. The diagnosis of CHI was based on elevated serum insulin (3.4-32.5 μIU/ml) and C-peptide (0.58-1.98 ng/ml) at the time of symptomatic hypoglycemia (BG≤41 mg/dl). Fourteen patients (13 males) presented at a median (range) age of 3 (1-270) days, seizures being the most common mode of presentation (78.6%). Ten patients were diazoxide-responsive, two were partially responsive, while two were unresponsive. Genetics was available for eight patients; ABCC8 (n=3, 1 novel) and HADH (n=2, both novel) were the most commonly mutated genes. OCT-LAR was offered to eight patients including four with diazoxide-responsive disease and was universally effective. We propose a cost-effective approach to use OCT-LAR in the management of CHI, which may also make it more cost-effective than diazoxide for diazoxide-responsive disease. Five of the 11 (45.5%) patients had evidence of neurological impairment; notably, two patients with HADH mutations had intellectual disability despite diazoxide-responsiveness. We report three novel mutations in CHI-associated genes. We demonstrate the effectiveness of and propose a cost-effective approach to use OCT-LAR in diazoxide-responsive CHI. Mutations in HADH may be associated with abnormal neurodevelopmental outcomes despite diazoxide-responsiveness.

AbstractIn 1998 the fetal insulin hypothesis proposed that lower birthweight and adult-onset type 2 diabetes are two phenotypes of the same genotype. Since then, advances in research investigating the role of genetics affecting insulin secretion and action have furthered knowledge of fetal insulin-mediated growth and the biology of type 2 diabetes. In this review, we discuss the historical research context from which the fetal insulin hypothesis originated and consider the position of the hypothesis in light of recent evidence. In summary, there is now ample evidence to support the idea that variants of certain genes which result in impaired pancreatic beta cell function and reduced insulin secretion contribute to both lower birthweight and higher type 2 diabetes risk in later life when inherited by the fetus. There is also evidence to support genetic links between type 2 diabetes secondary to reduced insulin action and lower birthweight but this applies only to loci implicated in body fat distribution and not those influencing insulin resistance via obesity or lipid metabolism by the liver. Finally, we also consider how advances in genetics are being used to explore alternative hypotheses, namely the role of the maternal intrauterine environment, in the relationship between lower birthweight and adult cardiometabolic disease.
. Graphical abstract

Maturity-onset diabetes of the young (MODY) classically describes dominantly inherited forms of monogenic diabetes diagnosed before 25 years of age due to pancreatic β-cell dysfunction. In contrast, mutations in certain MODY genes can also present with transient or persistent hyperinsulinemic hypoglycemia in newborn infants, reflecting instead β-cell dysregulation. of the MODY genes described to date, only hepatocyte nuclear factor-4-alpha (HNF4A; MODY1) and hepatocyte nuclear factor-1-alpha (HNF1A; MODY3) mutations may result in a biphasic phenotype of hypoglycemia in early life and hyperglycemia in later life. We report a family with a novel HNF4A mutation with diverse phenotypic presentations of glucose dysregulation. The proband was a term, appropriate-for-gestational age male infant with symptomatic hypoglycemia on day 3 of life needing high glucose infusion rate to maintain normoglycemia. He was born to a non-obese and non-diabetic mother. Glucose regulation was optimized using diazoxide upon confirmation of hyperinsulinism. Cascade genetic screening identified the same mutation in his father and elder sister, but mother was negative. Father was diagnosed with Type 1 diabetes at 15 years of age that required insulin therapy. Proband's elder sister, born at term appropriate for gestational age, presented with transient neonatal hypoglycemia needing parenteral glucose infusion for a week followed by spontaneous resolution. The paternal grandparents were negative for this mutation, confirming a paternal de novo mutation and autosomal dominant inheritance in this family. This pedigree suggests that the presence of early-onset paternal diabetes should prompt molecular testing in infants presenting in the newborn period with diazoxide-responsive hyperinsulinemic hypoglycemia, even in the absence of maternal diabetes and macrosomia.

ATP-dependent potassium (KATP) channels are present in the human pancreas, brain, nerve and muscle and play a crucial role in key biological pathways. In the pancreas, KATP channels regulate insulin secretion from beta cells in response to glucose. They comprise 4 Kir6.2 subunits, encoded by the KCNJ11 gene, which form the channel pore, and 4 SUR1 subunits, encoded by the ABCC8 gene, which regulate channel activity and form the binding site for sulphonylurea drugs.
Mutations in KATP channel genes account for ~half of cases of neonatal diabetes, which is diabetes diagnosed in the first 6 months of life; this may be permanent (PNDM) requiring lifelong treatment, or transient (TNDM) where the diabetes remits and relapses in later childhood or adulthood. Activating mutations in the KCNJ11 gene are the commonest cause of PNDM. A genetic diagnosis is crucial for patients with these mutations because ~90% can be treated with oral sulphonylureas instead of insulin injections. Sulphonylureas can bind and close mutant KATP channels allowing endogenous insulin secretion and resulting in improved metabolic control and quality of life at least in the short-term. Severe sulphonylurea-related hypoglycaemia does not occur but mild-moderate episodes, typically related to food, have been reported by affected individuals. The long-term response to sulphonylurea therapy and the regulation of insulin secretion in response to food in people with KCNJ11 mutations remain key research questions with important clinical implications.
Individuals with KCNJ11 PNDM can also have central nervous system (CNS) involvement; at its most severe this leads to Developmental delay, Epilepsy and Neonatal Diabetes (DEND) syndrome. Sulphonylurea therapy can also benefit the neurological features, which are thought to result from the action of sulphonylureas on brain KATP channels, although the response is only partial in contrast to the excellent glycaemic response. In order to provide appropriate multidisciplinary assessment and support, it is important to establish the specific neurological, psychiatric, and neuropsychological deficits that are present in children and adults with sulphonylurea-treated KCNJ11 neonatal diabetes, and their impact on affected families.
The overall aim of this thesis is to assess the response to sulphonylurea therapy in patients with PNDM due to mutations in the KCNJ11 gene, by undertaking clinical studies that investigate the glycaemic response as well as the CNS features in affected individuals.
In chapter 1 we assess the long-term efficacy and safety of sulphonylurea therapy in KCNJ11 PNDM, by following clinical outcomes relating to both glycaemia and neurological features over 10 years in 81 patients who transferred from insulin to sulphonylureas before December 2006. We show that sulphonylurea therapy is effective and safe long-term, with 93% of individuals remaining on sulphonylureas without adjunctive therapies at most recent follow-up with no reports of severe hypoglycaemia or severe side-effects in over 800 patient years, and normal growth and BMI in children. In addition, we show that neurological features are present in 38/81 individuals and despite initial improvement in 18 individuals on transfer to sulphonylureas, there is persistence of these features to some degree long-term.
In chapter 2 we assess the physiological response to different foods in adults >18 years with sulphonylurea-treated KCNJ11 PNDM, by measuring glucose, insulin and glucagon levels after a high-protein meal and a high-carbohydrate meal in 5 affected individuals and comparing these with 5 non-diabetic controls. We show that individuals with sulphonylurea treated KCNJ11 PNDM have similar insulin levels in response to both a carbohydrate and protein meal despite having higher glucose values in response to a carbohydrate meal than to a protein meal. This contrasts with controls who have higher insulin secretion after carbohydrate than protein and therefore more tightly regulated glucose levels in response to both meals. The findings suggest that individuals with sulphonylurea-treated KCNJ11 PNDM cannot modulate insulin secretion in response to glucose, consistent with a dependence on non-KATP pathways for insulin secretion.
In chapter 3 we assess the psychiatric and neuropsychological profile of children

BACKGROUND: Diabetes diagnosed within the first 6 months of life is defined as neonatal diabetes mellitus (NDM). Mutations in the KCNJ11, ABCC8, and INS genes are the most common cause of permanent NDM. In populations with a high rate of consanguinity, Wolcott-Rallison syndrome caused by biallelic EIF2AK3 mutations is common. METHODS: We studied the clinical characteristics and underlying genetic cause of disease in 15 individuals with diabetes onset before 6 months of age as defined by sustained hyperglycaemia requiring insulin treatment. Patients who had a remission of the diabetes, defined by a normal blood glucose and HbA1c value without insulin or sulphonylurea (SU) treatment, within the first 18 months of life were classified as having transient NDM (TNDM). RESULTS: We report 15 patients with NDM from 14 unrelated families, including 10 with reported parental consanguinity. 1/15 patients had a remission of diabetes, leading to a diagnosis of TNDM. Mutations were detected in 80% (n = 12/15) of the cohort (ABCC8 [n = 4], PTF1A-distal enhancer [n = 3], KCNJ11 [n = 2], EIF2AK3 [n = 1], INS [n = 1], and SLC19A2 [n = 1]). All cases were initially treated with multiple dose insulin injections. One patient with an ABCC8 mutation transitioned from insulin to SU resulting in improved metabolic control at the age of 20 years. CONCLUSION: Although the number of individuals born to consanguineous parents was considerably high in this cohort, KATP channel mutations (ABCC8/KCNJ11) were more common than EIF2AK3 mutations (n = 6 vs. n = 1). Genetic analyses should be performed in all NDM cases due to the potential impact on treatment and prognosis.

Mutations in the insulin receptor (INSR) gene are associated with insulin resistance and hyperglycaemia. Various autosomal dominant heterozygous INSR mutations leading to hyperinsulinemic hypoglycaemia (HH) have been described in adults and children (more than 3 years of age) but not in the neonatal period. Family 1: a small for gestational age (SGA) child born to a mother with gestational diabetes presented with persistent hypoglycaemia, was diagnosed with HH and responded well to diazoxide treatment. Diazoxide was gradually weaned and discontinued by 8 months of age. Later, the younger sibling had a similar course of illness. On genetic analysis a heterozygous INSR missense variant p.(Met1180Lys) was found in the siblings, mother and grandfather but not in the father. Family 2: a twin preterm and SGA baby presented with persistent hypoglycaemia, which was confirmed as HH. He responded to diazoxide, which was subsequently discontinued by 10 weeks of life. Genetic analysis revealed a novel heterozygous INSR missense variant p.(Arg1119Gln) in the affected twin and the mother. Family 3: an SGA child presented with diazoxide responsive HH. Diazoxide was gradually weaned and discontinued by 9 weeks of age. Genetic analysis revealed a novel heterozygous INSR p.(Arg1191Gln) variant in the proband and her father. We report, for the first time, an association of INSR mutation with neonatal HH responsive to diazoxide therapy that resolved subsequently. Our case series emphasizes the need for genetic analysis and long-term follow up of these patients.

Hyperinsulinemic hypoglycemia (HH) is characterized by unregulated insulin release, leading to persistently low blood glucose concentrations with lack of alternative fuels, which increases the risk of neurological damage in these patients. It is the most common cause of persistent and recurrent hypoglycemia in the neonatal period. HH may be primary, Congenital HH (CHH), when it is associated with variants in a number of genes implicated in pancreatic development and function. Alterations in fifteen genes have been recognized to date, being some of the most recently identified mutations in genes HK1, PGM1, PMM2, CACNA1D, FOXA2 and EIF2S3. Alternatively, HH can be secondary when associated with syndromes, intra-uterine growth restriction, maternal diabetes, birth asphyxia, following gastrointestinal surgery, amongst other causes. CHH can be histologically characterized into three groups: diffuse, focal or atypical. Diffuse and focal forms can be determined by scanning using fluorine-18 dihydroxyphenylalanine-positron emission tomography. Newer and improved isotopes are currently in development to provide increased diagnostic accuracy in identifying lesions and performing successful surgical resection with the ultimate aim of curing the condition. Rapid diagnostics and innovative methods of management, including a wider range of treatment options, have resulted in a reduction in co-morbidities associated with HH with improved quality of life and long-term outcomes. Potential future developments in the management of this condition as well as pathways to transition of the care of these highly vulnerable children into adulthood will also be discussed.

BACKGROUND: Hypoglycaemia due to hyperinsulinism (HI) is the commonest cause of severe, recurrent hypoglycaemia in childhood. Cohort outcomes of HI remain to be described and whilst previous follow up studies have focused on neurodevelopmental outcomes, there is no information available on feeding and auxology. AIM: We aimed to describe HI outcomes for auxology, medications, feeding and neurodevelopmental in a cohort up to age 5 years. METHOD: We reviewed medical records for all patients with confirmed HI over a three-year period in a single centre to derive a longitudinal dataset. RESULTS: Seventy patients were recruited to the study. Mean weight at birth was - 1.0 standard deviation scores (SDS) for age and sex, while mean height at 3 months was - 1.5 SDS. Both weight and height trended to the population median over the follow up period. Feeding difficulties were noted in 17% of patients at 3 months and this reduced to 3% by 5 years. At age 5 years, 11 patients (15%) had neurodevelopmental delay and of these only one was severe. Resolution of disease was predicted by lower maximum early diazoxide dose (p = 0.007) and being born SGA (p = 0.009). CONCLUSION: in a three-year cohort of HI patients followed up for 5 years, in spite of feeding difficulties and carbohydrate loading in early life, auxology parameters are normal in follow up. A lower than expected rate of neurodevelopmental delay could be attributed to prompt early treatment.

Background: Large contiguous gene deletions at the distal end of the short arm of chromosome 9 result in the complex multi-organ condition chromosome 9p deletion syndrome.  a range of clinical features can result from these deletions with the most common being facial dysmorphisms and neurological impairment. Congenital hyperinsulinism is a rarely reported feature of the syndrome with the genetic mechanism for the dysregulated insulin secretion being unknown.  Methods: We studied the clinical and genetic characteristics of 12 individuals with chromosome 9p deletions who had a history of neonatal hypoglycaemia. Using off-target reads generated from targeted next-generation sequencing of the genes known to cause hyperinsulinaemic hypoglycaemia (n=9), or microarray analysis (n=3), we mapped the minimal shared deleted region on chromosome 9 in this cohort. Targeted sequencing was performed in three patients to search for a recessive mutation unmasked by the deletion. Results: in 10/12 patients with hypoglycaemia, hyperinsulinism was confirmed biochemically. A range of extra-pancreatic features were also reported in these patients consistent with the diagnosis of the Chromosome 9p deletion syndrome. The minimal deleted region was mapped to 7.2 Mb, encompassing 38 protein-coding genes. In silico analysis of these genes highlighted SMARCA2 and RFX3 as potential candidates for the hypoglycaemia. Targeted sequencing performed on three of the patients did not identify a second disease-causing variant within the minimal deleted region. Conclusions: This study identifies 9p deletions as an important cause of hyperinsulinaemic hypoglycaemia and increases the number of cases reported with 9p deletions and hypoglycaemia to 15 making this a more common feature of the syndrome than previously appreciated.  Whilst the precise genetic mechanism of the dysregulated insulin secretion could not be determined in these patients, mapping the deletion breakpoints highlighted potential candidate genes for hypoglycaemia within the deleted region.

Aims/hypothesis: Diabetes diagnosed at

Background Congenital hyperinsulinism (CHI) occurs due to an unregulated insulin secretion from the pancreatic β-cells resulting in hypoglycaemia. Causative mutations in multiple genes have been reported. Phenotypic variability exists both within and between different genetic subgroups. Case presentation a male infant born at 35+6 weeks' gestation with a birth weight of 4.3 kg [+3.6 standard deviation score (SDS)] had recurrent hypoglycaemic episodes from birth. Biochemical investigations confirmed a diagnosis of CHI. Diazoxide was started and the dose was progressively increased to maintain euglycaemia. His father was slim and had been diagnosed with type 2 diabetes in his 30s. Sequence analysis identified a heterozygous hepatocyte nuclear factor 4 alpha (HNF4A) mutation (p.Arg245Pro, c.734G>C) and compound heterozygous ABCC8 mutations (p.Gly92Ser, c.274G>A and p.Ala1185Val, c.3554C>T) in the patient. The p.Ala1185Val ABCC8 mutation was inherited from his unaffected mother and the p.Arg245Pro HNF4A and p.Gly92Ser ABCC8 mutations from his father. All three mutations were predicted to be pathogenic. Identification of the HNF4A mutation in the father established a diagnosis of maturity-onset diabetes of the young (MODY), which enabled medication change resulting in improved glycaemic control. Conclusions We report a rare patient with CHI due to dual genetic aetiology. Although he is currently responsive to the maximum dose of diazoxide, the long-term prognosis remains unclear.

OBJECTIVE: Central nervous system (CNS) features in children with permanent neonatal diabetes (PNDM) due to KCNJ11 mutations have a major impact on affected families. Sulfonylurea therapy achieves outstanding metabolic control but only partial improvement in CNS features. The effects of KCNJ11 mutations on the adult brain and their functional impact are not well understood. We aimed to characterize the CNS features in adults with KCNJ11 PNDM compared with adults with INS PNDM. RESEARCH DESIGN AND METHODS: Adults with PNDM due to KCNJ11 mutations (n = 8) or INS mutations (n = 4) underwent a neurological examination and completed standardized neuropsychological tests/questionnaires about development/behavior. Four individuals in each group underwent a brain MRI scan. Test scores were converted to Z scores using normative data, and outcomes were compared between groups. RESULTS: in individuals with KCNJ11 mutations, neurological examination was abnormal in seven of eight; predominant features were subtle deficits in coordination/motor sequencing. All had delayed developmental milestones and/or required learning support/special schooling. Half had features and/or a clinical diagnosis of autism spectrum disorder. KCNJ11 mutations were also associated with impaired attention, working memory, and perceptual reasoning and reduced intelligence quotient (IQ) (median IQ KCNJ11 vs. INS mutations 76 vs. 111, respectively; P = 0.02). However, no structural brain abnormalities were noted on MRI. The severity of these features was related to the specific mutation, and they were absent in individuals with INS mutations. CONCLUSIONS: KCNJ11 PNDM is associated with specific CNS features that are not due to long-standing diabetes, persist into adulthood despite sulfonylurea therapy, and represent the major burden from KCNJ11 mutations.

Congenital hyperinsulinism (CHI) is a clinically and genetically heterogeneous disorder, characterized by dysregulated insulin secretion. Pathogenic variants in at least twelve different genes (ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A, HNF1A, UCP2, TRMT10A HK1, and PGM1) are known to cause CHI. Pathogenic variants in the GLUD1 gene, which encodes the enzyme glutamate dehydrogenase (GDH), account for 5% of the cases of congenital hyperinsulinemic hypoglycemia. Pathogenic variants in GLUD1 typically present in late infancy, are diet and/or diazoxide-responsive and cause protein-induced hyperinsulinemic hypoglycemia as insulin secretion is triggered by allosteric activation of GDH by leucine. The authors are presenting three unrelated Indian children, who manifested with fasting as well as dietary protein induced hypoglycemia in late infancy, and were diagnosed to have hyperinsulinemic hyperammonemic hypoglycemia due to pathogenic variants in GLUD1. Although the hypoglycemia responded to diazoxide, delayed diagnosis and irregular treatment had resulted in neurological problems in two of the three children. Early identification, appropriate dietary modifications and regular treatment with diazoxide can prevent adverse neurological outcome.

Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycemia in infants and children. Recessive inactivating mutations in the ABCC8 and KCNJ11 genes account for approximately 50% of all CHI cases. Hyperinsulinaemic hypoglycaemia in infancy and diabetes in later life have been reported in patients with HNF1A, HNF4A and ABCC8 mutations. Herein, we present a child who was diagnosed with CHI at birth, then developed diabetes mellitus at the age of nine years due to a novel homozygous missense, p.L171F (c.511C>T) mutation in exon 4 of ABCC8. The parents and one sibling were heterozygous carriers, whilst a younger sibling who had transient neonatal hypoglycemia was homozygous for the mutation. The mother and (maternal) uncle, who was also heterozygous for the mutation, developed diabetes within their third decade of life. The preliminary results of sulphonylurea (SU) treatment was suggestive of SU responsiveness. Patients with homozygous ABCC8 mutations can present with CHI in the newborn period, the hyperinsulinism can show variability in terms of clinical severity and age at presentation and can cause diabetes later in life. Patients with homozygous ABCC8 mutations who are managed medically should be followed long-term as they may be at increased risk of developing diabetes after many years.

The original version of this Article contained an error in the top left of Figure 2: the number 1 on the y-axis had been changed to 0 during the typesetting process. This has now been corrected in both the PDF and HTML versions of the Article.

Diazoxide is the first-line treatment for patients with hyperinsulinaemic hypoglycaemia (HH). Approximately 50% of patients with HH are diazoxide resistant. However, marked diazoxide sensitivity resulting in severe hyperglycaemia is extremely uncommon and not reported previously in the context of HH due to HNF4A mutation. We report a novel observation of exceptional diazoxide sensitivity in a patient with HH due to HNF4A mutation. A female infant presented with severe persistent neonatal hypoglycaemia and was diagnosed with HH. Standard doses of diazoxide (5 mg/kg/day) resulted in marked hyperglycaemia (maximum blood glucose 21.6 mmol/L) necessitating discontinuation of diazoxide. Lower dose of diazoxide (1.5 mg/kg/day) successfully controlled HH in the proband, which was subsequently confirmed to be due to a novel HNF4A mutation. At 3 years of age, the patient maintains age appropriate fasting tolerance on low dose diazoxide (1.8 mg/kg/day) and has normal development. Diagnosis in proband's mother and maternal aunt, both of whom carried HNF4A mutation and had been diagnosed with presumed type 1 and type 2 diabetes mellitus, respectively, was revised to maturity-onset diabetes of young (MODY). Proband's 5-year-old maternal cousin, also carrier of HNF4A mutation, had transient neonatal hypoglycaemia. To conclude, patients with HH due to HNF4A mutation may require lower diazoxide than other group of patients with HH. Educating the families about the risk of marked hyperglycaemia with diazoxide is essential. The clinical phenotype of HNF4A mutation can be extremely variable. Learning points: Awareness of risk of severe hyperglycaemia with diazoxide is important and patients/families should be accordingly educated. Some patients with HH due to HNF4A mutations may require lower than standard doses of diazoxide. The clinical phenotype of HNF4A mutation can be extremely variable.

Congenital hyperinsulinism (CHI) is the commonest cause of persistent and severe hypoglycemia in infancy due to unregulated insulin secretion from pancreatic β-cells. Prompt early diagnosis is important, as insulin reduces glucose supply to the brain, resulting in significant brain injury and risk of death. Histologically, CHI has focal and diffuse forms; in focal CHI, an inappropriate level of insulin is secreted from localized β-cell hyperplasia. We report a 4-month-old male infant, who presented with sudden illness and collapse without a recognized cause and died. Postmortem examination revealed pancreatic histopathology compatible with focal CHI. Immunofluoresence staining showed limited expression of p57kip2 β-cells reinforcing the diagnosis. Mutation testing for genes associated with CHI from DNA from the focal lesion was negative. This case highlights the recognition of focal CHI as a possible cause for sudden infant death. In children dying suddenly and unexpectedly, postmortem pancreatic sections should be carefully examined for focal CHI.

PURPOSE OF REVIEW: to highlight pathways important for the development of autoimmune diabetes by investigating shared mechanisms of disease in polygenic and monogenic diabetes. RECENT FINDINGS: Genome-wide association studies have identified 57 genetic risk loci for type 1 diabetes. Progress has been made in unravelling the mechanistic effects of some of these variants, providing key insights into the pathogenesis of type 1 diabetes. Seven monogenic disorders have also been described where diabetes features as part of an autoimmune syndrome. Studying these genes in relation to polygenic risk loci provides a unique opportunity to dissect pathways important for the development of immune-mediated diabetes. Monogenic autoimmune diabetes can result from the dysregulation of multiple pathways suggesting that small effects on many immune processes are required to drive the autoimmune attack on pancreatic beta cells in polygenic type 1 diabetes. A breakdown in central and peripheral immune tolerance is a common theme in the genetic mechanisms of both monogenic and polygenic disease which highlights the importance of these checkpoints in the development and treatment of islet autoimmunity.

PURPOSE: One of the greatest challenges currently facing those studying Mendelian disease is identifying the pathogenic variant from the long list produced by a next-generation sequencing test. We investigate the predictive ability of homozygosity mapping for identifying the regions likely to contain the causative variant. METHODS: We use 179 homozygous pathogenic variants from three independent cohorts to investigate the predictive power of homozygosity mapping. RESULTS: We demonstrate that homozygous pathogenic variants in our cohorts are disproportionately likely to be found within one of the largest regions of homozygosity: 80% of pathogenic variants are found in a homozygous region that is in the ten largest regions in a sample. The maximal predictive power is achieved in patients with 3 Mb from a telomere; this gives an area under the curve (AUC) of 0.735 and results in 92% of the causative variants being in one of the ten largest homozygous regions. CONCLUSION: This predictive power can be used to prioritize the list of candidate variants in gene discovery studies. When classifying a homozygous variant the size and rank of the region of homozygosity in which the candidate variant is located can also be considered as supporting evidence for pathogenicity.

Neonatal diabetes mellitus (NDM) is a monogenic form of diabetes resulting from mutations in more than 20 different genes encoding proteins playing a key role in the normal function of the pancreatic beta-cell. Mutations in the genes encoding the ATP-sensitive potassium channel, ABCC8, and KCNJ11 and insulin (INS) gene are the most common causes of NDM; however, in consanguineous populations, EIF2AK3 mutations are more common. Identification of the causative mutations by genetic testing is critical for appropriate management and to guide genetic counseling. To determine the genetic etiology of NDM in diabetic neonates and infants diagnosed before the age of 1 year and to describe their phenotype/genotype characteristics, DNA sequencing of coding regions and intronic boundaries of ABCC8, KCNJ11, INS, and EIF2AK3 genes was undertaken in 20 patients. Further, targeted next-generation sequencing was performed for other genes known to cause NDM. ABCC8 mutations were found in two patients (10%), with compound heterozygous mutations (p.N131 K/p.R598*) in one patient and a homozygous mutation (p.R1554Q) in the another patient. Heterozygous p.A174G and p.V59M mutations of KCNJ11 were identified in two patients (10%), and homozygous EIF2AK3 mutations were identified in two further patients (p.T905fs and p.R653T) (10%). No INS mutations were identified. Further testing identified a SLC19A2 mutation (p.W387*) in one patient (5%) and the same homozygous GCK mutation in two siblings (p.A188T). ABCC8, KCNJ11, and EIF2AK3 mutations were the main genetic causes of permanent NDM among Egyptian neonates.

We report a case of partial diazoxide responsiveness in a child with severe congenital hyperinsulinaemic hypoglycaemia (CHI) due to a homozygous ABCC8 mutation. A term baby, with birth weight 3.8 kg, born to consanguineous parents presented on day 1 of life with hypoglycaemia. Hypoglycaemia screen confirmed CHI. Diazoxide was commenced on day 7 due to ongoing elevated glucose requirements (15 mg/kg/min), but despite escalation to a maximum dose (15 mg/kg/day), intravenous (i.v.) glucose requirement remained high (13 mg/kg/min). Genetic testing demonstrated a homozygous ABCC8 splicing mutation (c.2041-1G>C), consistent with a diffuse form of CHI. Diazoxide treatment was therefore stopped and subcutaneous (s.c.) octreotide infusion commenced. Despite this, s.c. glucagon and i.v. glucose were required to prevent hypoglycaemia. A trial of sirolimus and near-total pancreatectomy were considered, however due to the significant morbidity potentially associated with these, a further trial of diazoxide was commenced at 1.5 months of age. At a dose of 10 mg/kg/day of diazoxide and 40 µg/kg/day of octreotide, both i.v. glucose and s.c. glucagon were stopped as normoglycaemia was achieved. CHI due to homozygous ABCC8 mutation poses management difficulties if the somatostatin analogue octreotide is insufficient to prevent hypoglycaemia. Diazoxide unresponsiveness is often thought to be a hallmark of recessively inherited ABCC8 mutations. This patient was initially thought to be non-responsive, but this case highlights that a further trial of diazoxide is warranted, where other available treatments are associated with significant risk of morbidity. Learning points: Homozygous ABCC8 mutations are commonly thought to cause diazoxide non-responsive hyperinsulinaemic hypoglycaemia. This case highlights that partial diazoxide responsiveness in homozygous ABCC8 mutations may be present. Trial of diazoxide treatment in combination with octreotide is warranted prior to considering alternative treatments, such as sirolimus or near-total pancreatectomy, which are associated with more significant side effects.

Objective Insulin secretion in sulfonylurea-treated KCNJ11 permanent neonatal diabetes mellitus (PNDM) is thought to be mediated predominantly through amplifying non-K ATP -channel pathways such as incretins. Affected individuals report symptoms of postprandial hypoglycemia after eating protein/fat-rich foods. We aimed to assess the physiological response to carbohydrate and protein/fat in people with sulfonylurea-treated KCNJ11 PNDM. Research design and methods 5 adults with sulfonylurea-treated KCNJ11 PNDM and five age, sex and body mass index-matched controls without diabetes had a high-carbohydrate and high-protein/fat meal on two separate mornings. Insulin(i) and glucose(g) were measured at baseline then regularly over 4 hours after the meal. Total area under the curve (tAUC) for insulin and glucose was calculated over 4 hours and compared between meals in controls and KCNJ11 cases. Results in controls, glucose values after carbohydrate and protein/fat were similar (median glucose tAUC 0-4h 21.4 vs 19.7 mmol/L, p=0.08). In KCNJ11 cases glucose levels were higher after carbohydrate than after protein/fat (median glucose tAUC 0-4h 58.1 vs 31.3 mmol/L, p=0.04). These different glycemic responses reflected different patterns of insulin secretion: in controls, insulin secretion was greatly increased after carbohydrate versus protein/fat (median insulin tAUC 0-4h 727 vs 335 pmol/L, p=0.04), but in KCNJ11 cases insulin secretion was similar after carbohydrate and protein/fat (median insulin tAUC 0-4h 327 vs 378 pmol/L, p=0.50). Conclusions Individuals with sulfonylurea-treated KCNJ11 PNDM produce similar levels of insulin in response to both carbohydrate and protein/fat meals despite carbohydrate resulting in much higher glucose levels and protein/fat resulting in relatively low glucose levels. This suggests in an inability to modulate insulin secretion in response to glucose levels, consistent with a dependence on non-K ATP pathways for insulin secretion. Trial registration number NCT02921906.

Background: Large contiguous gene deletions at the distal end of the short arm of chromosome 9 result in the complex multi-organ condition chromosome 9p deletion syndrome.  a range of clinical features can result from these deletions with the most common being facial dysmorphisms and neurological impairment. Congenital hyperinsulinism is a rarely reported feature of the syndrome with the genetic mechanism for the dysregulated insulin secretion being unknown.  Methods: We studied the clinical and genetic characteristics of 12 individuals with chromosome 9p deletions who had a history of neonatal hypoglycaemia. Using off-target reads generated from targeted next-generation sequencing of the genes known to cause hyperinsulinaemic hypoglycaemia (n=9), or microarray analysis (n=3), we mapped the minimal shared deleted region on chromosome 9 in this cohort. Targeted sequencing was performed in three patients to search for a recessive mutation unmasked by the deletion. Results: in 10/12 patients with hypoglycaemia, hyperinsulinism was confirmed biochemically. A range of extra-pancreatic features were also reported in these patients consistent with the diagnosis of the Chromosome 9p deletion syndrome. The minimal deleted region was mapped to 7.2 Mb, encompassing 38 protein-coding genes. In silico analysis of these genes highlighted SMARCA2 and RFX3 as potential candidates for the hypoglycaemia. Targeted sequencing performed on three of the patients did not identify a second disease-causing variant within the minimal deleted region. Conclusions: This study identifies 9p deletions as an important cause of hyperinsulinaemic hypoglycaemia and increases the number of cases reported with 9p deletions and hypoglycaemia to 15 making this a more common feature of the syndrome than previously appreciated.  Whilst the precise genetic mechanism of the dysregulated insulin secretion could not be determined in these patients, mapping the deletion breakpoints highlighted potential candidate genes for hypoglycaemia within the deleted region.

Background: Large contiguous gene deletions at the distal end of the short arm of chromosome 9 result in the complex multi-organ condition chromosome 9p deletion syndrome.  a range of clinical features can result from these deletions with the most common being facial dysmorphisms and neurological impairment. Congenital hyperinsulinism is a rarely reported feature of the syndrome with the genetic mechanism for the dysregulated insulin secretion being unknown.  Methods: We studied the clinical and genetic characteristics of 12 individuals with chromosome 9p deletions who had a history of neonatal hypoglycaemia. Using off-target reads generated from targeted next-generation sequencing of the genes known to cause hyperinsulinaemic hypoglycaemia (n=9), or microarray analysis (n=3), we mapped the minimal shared deleted region on chromosome 9 in this cohort. Targeted sequencing was performed in three patients to search for a recessive mutation unmasked by the deletion. Results: in 10/12 patients with hypoglycaemia, hyperinsulinism was confirmed biochemically. A range of extra-pancreatic features were also reported in these patients consistent with the diagnosis of the Chromosome 9p deletion syndrome. The minimal deleted region was mapped to 7.2 Mb, encompassing 38 protein-coding genes. In silico analysis of these genes highlighted SMARCA2 and RFX3 as potential candidates for the hypoglycaemia. Targeted sequencing performed on three of the patients did not identify a second disease-causing variant within the minimal deleted region. Conclusions: This study identifies 9p deletions as an important cause of hyperinsulinaemic hypoglycaemia and increases the number of cases reported with 9p deletions and hypoglycaemia to 15 making this a more common feature of the syndrome than previously appreciated.  Whilst the precise genetic mechanism of the dysregulated insulin secretion could not be determined in these patients, mapping the deletion breakpoints highlighted potential candidate genes for hypoglycaemia within the deleted region.

Biomolecular monitoring in the gastrointestinal tract could offer rapid, precise disease detection and management but is impeded by access to the remote and complex environment. Here, we present an ingestible micro-bio-electronic device (IMBED) for in situ biomolecular detection based on environmentally resilient biosensor bacteria and miniaturized luminescence readout electronics that wirelessly communicate with an external device. As a proof of concept, we engineer heme-sensitive probiotic biosensors and demonstrate accurate diagnosis of gastrointestinal bleeding in swine. Additionally, we integrate alternative biosensors to demonstrate modularity and extensibility of the detection platform. IMBEDs enable new opportunities for gastrointestinal biomarker discovery and could transform the management and diagnosis of gastrointestinal disease.

Objective: Hyperinsulinaemic hypoglycaemia (HH) can occur in isolation or more rarely feature as part of a syndrome. Screening for mutations in the “syndromic” HH genes is guided by phenotype with genetic testing used to confirm the clinical diagnosis. As HH can be the presenting feature of a syndrome, it is possible that mutations will be missed as these genes are not routinely screened in all newly diagnosed individuals. We investigated the frequency of pathogenic variants in syndromic genes in infants with HH who had not been clinically diagnosed with a syndromic disorder at referral for genetic testing. Design: We used genome sequencing data to assess the prevalence of mutations in syndromic HH genes in an international cohort of patients with HH of unknown genetic cause. Patients: We undertook genome sequencing in 82 infants with HH without a clinical diagnosis of a known syndrome at referral for genetic testing. Measurements: Within this cohort, we searched for the genetic aetiologies causing 20 different syndromes where HH had been reported as a feature. Results: We identified a pathogenic KMT2D variant in a patient with HH diagnosed at birth, confirming a genetic diagnosis of Kabuki syndrome. Clinical data received following the identification of the mutation highlighted additional features consistent with the genetic diagnosis. Pathogenic variants were not identified in the remainder of the cohort. Conclusions: Pathogenic variants in the syndromic HH genes are rare; thus, routine testing of these genes by molecular genetics laboratories is unlikely to be justified in patients without syndromic phenotypes.

BACKGROUND: Persistent hyperinsulinemic hypoglycemia of infancy (PHHI), also known as congenital hyperinsulinism, has been known to go into spontaneous remission, with patients developing diabetes in later life. A temporary phase of hyperglycemia is, however, rarely reported. CASE PRESENTATION: We describe a 16-month-old child, a known case of diazoxide responsive PHHI, presenting with mixed hyperglycemic hyperosmolar coma and ketoacidosis with rhabdomyolysis while on diazoxide treatment. The patient required temporary cessation of diazoxide and initiation of insulin infusion, followed by a relapse of hypoglycemia again necessitating diazoxide therapy. CONCLUSIONS: Hyperosmolar coma with ketoacidosis is a rare side-effect of diazoxide therapy, documented even in patients with persistent hyperinsulinemic hypoglycemia of infancy.

We compare the two main classes of measures of population structure in genetics: (i) fixation measures such as FST,GST, and θ and (ii) allelic differentiation measures such as Jost's D and entropy differentiation. These two groups of measures quantify complementary aspects of population structure, which have no necessary relationship with each other. We focus especially on empirical aspects of population structure relevant to conservation analyses. At the empirical level, the first set of measures quantify nearness to fixation, while the second set of measures quantify relative degree of allelic differentiation. The two sets of measures do not compete with each other. Fixation measures are often misinterpreted as measures of allelic differentiation in conservation applications; we give examples and theoretical explanations showing why this interpretation can mislead. This misinterpretation has led to the mistaken belief that the absolute number of migrants determines allelic differentiation between demes when mutation rate is low; we show that in the finite island model, the absolute number of migrants determines nearness to fixation, not allelic differentiation. We show that a different quantity, the factor that controls Jost's D, is a good predictor of the evolution of the actual genetic divergence between demes at equilibrium in this model. We also show that when conservation decisions require judgments about differences in genetic composition between demes, allelic differentiation measures should be used instead of fixation measures. Allelic differentiation of fast-mutating markers can be used to rank pairs or sets of demes according to their differentiation, but the allelic differentiation at coding loci of interest should be directly measured in order to judge its actual magnitude at these loci.

BACKGROUND: KCNJ11 mutations cause permanent neonatal diabetes through pancreatic ATP-sensitive potassium channel activation. 90% of patients successfully transfer from insulin to oral sulfonylureas with excellent initial glycaemic control; however, whether this control is maintained in the long term is unclear. Sulfonylurea failure is seen in about 44% of people with type 2 diabetes after 5 years of treatment. Therefore, we did a 10-year multicentre follow-up study of a large international cohort of patients with KCNJ11 permanent neonatal diabetes to address the key questions relating to long-term efficacy and safety of sulfonylureas in these patients. METHODS: in this multicentre, international cohort study, all patients diagnosed with KCNJ11 permanent neonatal diabetes at five laboratories in Exeter (UK), Rome (Italy), Bergen (Norway), Paris (France), and Krakow (Poland), who transferred from insulin to oral sulfonylureas before Nov 30, 2006, were eligible for inclusion. Clinicians collected clinical characteristics and annual data relating to glycaemic control, sulfonylurea dose, severe hypoglycaemia, side-effects, diabetes complications, and growth. The main outcomes of interest were sulfonylurea failure, defined as permanent reintroduction of daily insulin, and metabolic control, specifically HbA1c and sulfonylurea dose. Neurological features associated with KCNJ11 permanent neonatal diabetes were also assessed. This study is registered with ClinicalTrials.gov, number NCT02624817. FINDINGS: 90 patients were identified as being eligible for inclusion and 81 were enrolled in the study and provided long-term (>5·5 years cut-off) outcome data. Median follow-up duration for the whole cohort was 10·2 years (IQR 9·3-10·8). At most recent follow-up (between Dec 1, 2012, and Oct 4, 2016), 75 (93%) of 81 participants remained on sulfonylurea therapy alone. Excellent glycaemic control was maintained for patients for whom we had paired data on HbA1c and sulfonylurea at all time points (ie, pre-transfer [for HbA1c], year 1, and most recent follow-up; n=64)-median HbA1c was 8·1% (IQR 7·2-9·2; 65·0 mmol/mol [55·2-77·1]) before transfer to sulfonylureas, 5·9% (5·4-6·5; 41·0 mmol/mol [35·5-47·5]; p

BACKGROUND: Neonatal diabetes mellitus (NDM) is a rare disorder worldwide where diabetes is diagnosed in the first 6 months of life. However, Oman has a relatively high incidence of NDM. METHODS: in this study, we investigated the genetic etiologies underlying NDM and their prevalence in Oman. We collected a cohort of 24 NDM patients, with and without genetic diagnosis, referred to our center from 2007 to 2015. All patients without a genetic diagnosis were tested for mutations in 23 NDM-associated genes using a custom-targeted next-generation sequencing (NGS) panel and methylation analysis of the 6q24 locus. RESULTS: a genetic abnormality was detected in 15/24 (62.5%) of our Omani NDM patients. We report the detection of 6q24 methylation abnormalities and KCNJ11 mutations for the first time in Omani NDM patients. Unlike Western populations where NDM is predominantly due to mutations in the KCNJ11, ABCC8 and INS genes, NDM due to homozygous GCK gene mutations were most prevalent in Oman, having been observed in seven out of 15 NDM patients in whom we established the genetic etiology. This reflects the high degree of consanguinity which makes recessive conditions more likely. CONCLUSIONS: the results of this study are likely to impact any future strategy to introduce genetic testing for NDM disorders within the national healthcare system in Oman.

Identifying and monitoring locally adaptive genetic variation can have direct utility for conserving species at risk, especially when management may include actions such as translocations for restoration, genetic rescue, or assisted gene flow. However, genomic studies of local adaptation require careful planning to be successful, and in some cases may not be a worthwhile use of resources. Here, we offer an adaptive management framework to help conservation biologists and managers decide when genomics is likely to be effective in detecting local adaptation, and how to plan assessment and monitoring of adaptive variation to address conservation objectives. Studies of adaptive variation using genomic tools will inform conservation actions in many cases, including applications such as assisted gene flow and identifying conservation units. In others, assessing genetic diversity, inbreeding, and demographics using selectively neutral genetic markers may be most useful. and in some cases, local adaptation may be assessed more efficiently using alternative approaches such as common garden experiments. Here, we identify key considerations of genomics studies of locally adaptive variation, provide a road map for successful collaborations with genomics experts including key issues for study design and data analysis, and offer guidelines for interpreting and using results from genomic assessments to inform monitoring programs and conservation actions.

The β-cell-enriched MAFA transcription factor plays a central role in regulating glucose-stimulated insulin secretion while also demonstrating oncogenic transformation potential in vitro. No disease-causing MAFA variants have been previously described. We investigated a large pedigree with autosomal dominant inheritance of diabetes mellitus or insulinomatosis, an adult-onset condition of recurrent hyperinsulinemic hypoglycemia caused by multiple insulin-secreting neuroendocrine tumors of the pancreas. Using exome sequencing, we identified a missense MAFA mutation (p.Ser64Phe, c.191C>T) segregating with both phenotypes of insulinomatosis and diabetes. This mutation was also found in a second unrelated family with the same clinical phenotype, while no germline or somatic MAFA mutations were identified in nine patients with sporadic insulinomatosis. In the two families, insulinomatosis presented more frequently in females (eight females/two males) and diabetes more often in males (12 males/four females). Four patients from the index family, including two homozygotes, had a history of congenital cataract and/or glaucoma. The p.Ser64Phe mutation was found to impair phosphorylation within the transactivation domain of MAFA and profoundly increased MAFA protein stability under both high and low glucose concentrations in β-cell lines. In addition, the transactivation potential of p.Ser64Phe MAFA in β-cell lines was enhanced compared with wild-type MAFA. In summary, the p.Ser64Phe missense MAFA mutation leads to familial insulinomatosis or diabetes by impacting MAFA protein stability and transactivation ability. The human phenotypes associated with the p.Ser64Phe MAFA missense mutation reflect both the oncogenic capacity of MAFA and its key role in islet β-cell activity.

Monogenic diabetes represents a heterogeneous group of disorders resulting from a single gene defect leading to disruption of insulin secretion or a reduction in the number of beta cells. Despite the classification of monogenic diabetes into neonatal diabetes or maturity onset diabetes of the young (MODY) according to age of onset, not every case can be classified into those 2 groups. We evaluated patients with monogenic diabetes diagnosed during the last 10 year period. Type 1 DM, MODY, and patients with negative autoantibodies and no mutation in a known gene were excluded from the study. Thirteen patients were diagnosed with monogenic diabetes in Department of Pediatric Endocrinology, Ankara University School of Medicine, Ankara, Turkey. Five of them were diagnosed after 6 months of age. Five had a KATP channel defect. Mutations in genes resulting in destruction of beta cells were detected in 7 patients, with 4 cases having a WFS, 2 an LRBA, and one a IL2RA mutation. Additional systemic findings were seen in 6/13 patients, with 5/6 having severe immune system dysfunction. Treatment with sulphonylurea was successful in two patients. The other patients were given insulin in differing doses. Four patients died during follow-up, three of which had immune system dysfunction. Monogenic diabetes can be diagnosed after 6 months of age, even with positive autoantibodies. Immune dysfunction was a common feature in our cohort and should be investigated in all patients with early-onset monogenic diabetes. Mortality of patients with monogenic diabetes and additional autoimmunity was high in our cohort and is likely to reflect the multisystem nature of these diseases.

CONTEXT: Monogenic partial lipodystrophy is a genetically heterogeneous disease where only variants with specific genetic mechanisms are causative. Three heterozygous protein extending frameshift variants in PLIN1 have been reported to cause a phenotype of partial lipodystrophy and insulin resistance. OBJECTIVE: We investigated if null variants in PLIN1 cause lipodystrophy. METHODS: As part of a targeted sequencing panel test, we sequenced PLIN1 in 2208 individuals. We also investigated the frequency of PLIN1 variants in the gnomAD database, and the type 2 diabetes knowledge portal. RESULTS: We identified 6/2208 (1 in 368) individuals with a PLIN1 null variant. None of these individuals had clinical or biochemical evidence of overt lipodystrophy. Additionally, 14/17,000 (1 in 1214) individuals with PLIN1 null variants in the type 2 diabetes knowledge portal showed no association with biomarkers of lipodystrophy. PLIN1 null variants occur too frequently in gnomAD (126/138,632; 1 in 1100) to be a cause of rare overt monogenic partial lipodystrophy. CONCLUSIONS: Our study suggests that heterozygous variants that are predicted to result in PLIN1 haploinsufficiency are not a cause of familial partial lipodystrophy and should not be reported as disease-causing variants by diagnostic genetic testing laboratories. This finding is in keeping with other known monogenic causes of lipodystrophy, such as PPARG and LMNA, where only variants with specific genetic mechanisms cause lipodystrophy.

The basic helix-loop-helix (bHLH) transcription factor, neuronal differentiation 1 (NEUROD1) (also known as BETA2) is involved in the development of neural elements and endocrine pancreas. Less than 10 reports of adult-onset non-insulin-dependent diabetes mellitus (NIDDM) due to heterozygous NEUROD1 mutations and 2 cases with permanent neonatal diabetes mellitus (PNDM) and neurological abnormalities due to homozygous NEUROD1 mutations have been published. A 13 year-old female was referred to endocrine department due to hyperglycemia. She was on insulin therapy following a diagnosis of neonatal diabetes mellitus (NDM) at the age of 9-weeks but missed regular follow-up. Parents are second cousin. There was a significant family history of adult onset NIDDM including patient's father. Auxological measurements were within normal ranges. On laboratory examination blood glucose was 33.2 mmol/L with undetectable c-peptide and glycosylated hemoglobin level of 8.9% (73.8 mmol/mol). She had developed difficulty in walking at the age of 4 years which had worsened over time. On further evaluation, a diagnosis of visual impairment, mental retardation, ataxic gait, retinitis pigmentosa and sensory-neural deafness were considered. Cranial magnetic resonance imaging revealed cerebellar hypoplasia. Molecular genetic analysis using targeted next generation sequencing detected a novel homozygous missense mutation, p.Ile150Asn(c.449T>A), in NEUROD1. Both parents and 2 unaffected siblings were heterozygous for the mutation. We report the third case of PNDM with neurological abnormalities caused by homozygous NEUROD1 mutation, the first caused by a missense mutation. Heterozygous carriers of the p.Ile150Asn mutation were either unaffected or diagnosed with diabetes in adulthood. It is currently unclear whether the NEUROD1 heterozygous mutation has contributed to diabetes development in these individuals.

AIMS/HYPOTHESIS: Diabetes is one of the cardinal features of thiamine-responsive megaloblastic anaemia (TRMA) syndrome. Current knowledge of this rare monogenic diabetes subtype is limited. We investigated the genotype, phenotype and response to thiamine (vitamin B1) in a cohort of individuals with TRMA-related diabetes. METHODS: We studied 32 individuals with biallelic SLC19A2 mutations identified by Sanger or next generation sequencing. Clinical details were collected through a follow-up questionnaire. RESULTS: We identified 24 different mutations, of which nine are novel. The onset of the first TRMA symptom ranged from birth to 4 years (median 6 months [interquartile range, IQR 3-24]) and median age at diabetes onset was 10 months (IQR 5-27). At presentation, three individuals had isolated diabetes and 12 had asymptomatic hyperglycaemia. Follow-up data was available for 15 individuals treated with thiamine for a median 4.7 years (IQR 3-10). Four patients were able to stop insulin and seven achieved better glycaemic control on lower insulin doses. These 11 patients were significantly younger at diabetes diagnosis (p = 0.042), at genetic testing (p = 0.01) and when starting thiamine (p = 0.007) compared with the rest of the cohort. All patients treated with thiamine became transfusion-independent and adolescents achieved normal puberty. There were no additional benefits of thiamine doses >150 mg/day and no reported side effects up to 300 mg/day. CONCLUSIONS/INTERPRETATION: in TRMA syndrome, diabetes can be asymptomatic and present before the appearance of other features. Prompt recognition is essential as early treatment with thiamine can result in improved glycaemic control, with some individuals becoming insulin-independent. DATA AVAILABILITY: SLC19A2 mutation details have been deposited in the Decipher database ( https://decipher.sanger.ac.uk/ ).

Sirolimus has been reported to be effective in the treatment of the diffuse form of congenital hyperinsulinism (CHI), unresponsive to diazoxide and octreotide, without causing severe side effects. Two newborns with CHI due to homozygous ABCC8 gene mutations were started on sirolimus aged 21 and 17 days, due to lack of response to medical treatment. A good response to sirolimus was observed. At follow-up after ten and two months of treatment, liver enzymes were found to be increased [serum sirolimus level 1.4 ng/mL (normal range: 5-15), aspartate aminotransferase (AST): 298U/L, alanine aminotransferase (ALT): 302U/L and serum sirolimus level: 9.9 ng/mL, AST: 261U/L, ALT: 275U/L, respectively]. In Case 1, discontinuation of the drug resulted in normalization of liver enzymes within three days. Two days after normalization, sirolimus was restarted at a lower dose, which resulted in a repeated increase in transferases. In Case 2, a reduction of sirolimus dose caused normalization of liver enzymes within ten days. When the dose was increased, enzymes increased within three days. Sirolimus was discontinued in both cases. The rapid normalization of liver enzyme levels after sirolimus withdrawal or dose reduction; elevation of transaminases after restart or dose increase and rapid normalization after sirolimus withdrawal were findings strongly suggestive of sirolimus-induced hepatitis. To the best of our knowledge, this is the first report of sirolimus-induced hepatitis in CHI. Sirolimus is a promising drug for CHI patients who are unresponsive to medical treatment, but physicians should be vigilant for adverse effects on liver function.

Congenital hyperinsulinaemic hypoglycaemia (HH) can occur in isolation or it may present as part of a wider syndrome. For approximately 40%-50% of individuals with this condition, sequence analysis of the known HH genes identifies a causative mutation. Identifying the underlying genetic aetiology in the remaining cases is important as a genetic diagnosis will inform on recurrence risk, may guide medical management and will provide valuable insights into β-cell physiology. We sequenced the exome of a child with persistent diazoxide-responsive HH, mild aortic insufficiency, severe hypotonia, and developmental delay as well as the unaffected parents. This analysis identified a de novo mutation, p.G403D, in the proband's CACNA1D gene. CACNA1D encodes the main L-type voltage-gated calcium channel in the pancreatic β-cell, a key component of the insulin secretion pathway. The p.G403D mutation had been reported previously as an activating mutation in an individual with primary hyper-aldosteronism, neuromuscular abnormalities, and transient hypoglycaemia. Sequence analysis of the CACNA1D gene in 60 further cases with HH did not identify a pathogenic mutation. Identification of an activating CACNA1D mutation in a second patient with congenital HH confirms the aetiological role of CACNA1D mutations in this disorder. A genetic diagnosis is important as treatment with a calcium channel blocker may be an option for the medical management of this patient.

The pancreatic ATP-sensitive K+ (K-ATP) channel is a key regulator of insulin secretion. Gain-of-function mutations in the genes encoding the Kir6.2 (KCNJ11) and SUR1 (ABCC8) subunits of the channel cause neonatal diabetes, whilst loss-of-function mutations in these genes result in congenital hyperinsulinism. We report two patients with neonatal diabetes in whom we unexpectedly identified recessively inherited loss-of-function mutations. The aim of this study was to investigate how a homozygous nonsense mutation in ABCC8 could result in neonatal diabetes. The ABCC8 p.Glu747. was identified in two unrelated Vietnamese patients. This mutation is located within the in-frame exon 17 and RNA studies confirmed (a) the absence of full length SUR1 mRNA and (b) the presence of the alternatively spliced transcript lacking exon 17. Successful transfer of both patients to sulphonylurea treatment suggests that the altered transcript expression enhances the sensitivity of the K-ATP channel to Mg-ADP/ATP. This is the first report of an ABCC8 nonsense mutation causing a gain-of-channel function and these findings extend the spectrum of K-ATP channel mutations observed in patients with neonatal diabetes.

BACKGROUND: Haploinsufficiency of the GATA6 transcription factor gene was recently found to be the most common cause of pancreatic agenesis, a rare cause of neonatal diabetes mellitus. Although most cases are de novo, we describe three siblings with inherited GATA6 haploinsufficiency and the rare finding of parental mosaicism. CASE PRESENTATION: the proband was born at term with severe intrauterine growth restriction, the first child of non-consanguineous parents. Diabetes occurred on day of life 1 with pancreatic exocrine insufficiency noted at several months of age. Pancreatic agenesis with absent gallbladder was confirmed when he underwent congenital diaphragmatic hernia and intestinal malrotation repair. A patent ductus arteriosus and pulmonary stenosis were repaired in infancy. Neurocognitive development has been normal. A second pregnancy was terminated due to tetralogy of Fallot and pulmonary hypoplasia secondary to congenital diaphragmatic hernia. The fetus also demonstrated severe pancreatic hypoplasia, gallbladder agenesis and intestinal rotation abnormalities. Despite severe hypoplasia, the pancreas demonstrated normal islet histology. Another sibling was found to have multiple cardiac abnormalities, requiring procedural intervention. Given the proband's spectrum of congenital anomalies, Sanger sequencing of the GATA6 gene was performed, revealing a novel heterozygous c.635_660del frameshift mutation (p.Pro212fs). The mutation is predicted to be pathogenic, resulting in inclusion of a premature stop codon and likely degradation of the gene transcript by nonsense-mediated decay. The abortus and the sibling with the cardiac defect were both found to have the mutation, while the father and remaining sibling were negative. The mother, who is healthy with no evidence of diabetes or cardiac disease, is mosaic for the mutation at a level of 11% in her peripheral leukocytes by next-generation sequencing. CONCLUSION: We highlight a rare mechanism of pancreatic agenesis, this being only the second report of parental mosaicism for a GATA6 mutation and one of a handful of inherited cases. We also further define the phenotypic variability of GATA6 haploinsufficiency, even in individuals carrying the same mutation. Mutations in GATA6 should be strongly considered in cases of diabetes due to pancreatic hypoplasia or agenesis, and potentially affected family members should be tested regardless of phenotype.

BACKGROUND: Congenital hyperinsulinism (CHI) can present with considerable clinical heterogeneity which may be due to differences in the underlying genetic etiology. We present two siblings with hyperinsulinaemic hypoglycaemia (HH) and marked clinical heterogeneity caused by compound heterozygosity for the same two novel ABCC8 mutations. CASE PRESENTATION: the index patient is a 3-year-old boy with hypoglycaemic episodes presenting on the first day of life. HH was diagnosed and treatment with intravenous glucose and diazoxide was initiated. Currently he has normal physical and neurological development, with occasional hypoglycaemic episodes detected following continuous fasting on treatment with diazoxide. The first-born 8-year-old sibling experienced severe postnatal hypoglycaemia, generalised seizures and severe brain damage despite diazoxide treatment. The latter was stopped at 6-months of age with no further registered hypoglycaemia. Genetic testing showed that both children were compound heterozygotes for two novel ABCC8 missense mutations p.I60N (c.179T>A) and p.G1555V (c.4664G>T). CONCLUSIONS: These ABCC8 missense mutations warrant further studies mainly because of the variable clinical presentation and treatment response.

Neonatal diabetes is frequently part of a complex syndrome with extrapancreatic features: 18 genes causing syndromic neonatal diabetes have been identified to date. There are still patients with neonatal diabetes who have novel genetic syndromes. We performed exome sequencing in a patient and his unrelated, unaffected parents to identify the genetic etiology of a syndrome characterized by neonatal diabetes, sensorineural deafness, and congenital cataracts. Further testing was performed in 311 patients with diabetes diagnosed before 1 year of age in whom all known genetic causes had been excluded. We identified 5 patients, including the initial case, with three heterozygous missense mutations in WFS1 (4/5 confirmed de novo). They had diabetes diagnosed before 12 months (2 before 6 months) (5/5), sensorineural deafness diagnosed soon after birth (5/5), congenital cataracts (4/5), and hypotonia (4/5). In vitro studies showed that these WFS1 mutations are functionally different from the known recessive Wolfram syndrome-causing mutations, as they tend to aggregate and induce robust endoplasmic reticulum stress. Our results establish specific dominant WFS1 mutations as a cause of a novel syndrome including neonatal/infancy-onset diabetes, congenital cataracts, and sensorineural deafness. This syndrome has a discrete pathophysiology and differs genetically and clinically from recessive Wolfram syndrome.

In this report, we present the first known case of intermediate developmental delay, epilepsy and permanent neonatal diabetes (DEND) syndrome caused by a Q52R mutation in the KCNJ11 gene who was successfully switched (at age 1.3 years) to sulphonylurea monotherapy, namely glibenclamide. The most recent evaluation, after 2 years, showed a glycated hemoglobin level of 6.0% (42 mmol/mol). This mutation is so severe that none of the previously reported four cases were able to switch from insulin to sulphonylurea monotherapy. The Q52R mutation seems to have a chance of positive response to glibenclamide administered every 3-6 h instead of the classical 8-12 h, in doses around or above 2.5 mg/kg/day.

Finding new causes of monogenic diabetes helps understand glycaemic regulation in humans. To find novel genetic causes of maturity-onset diabetes of the young (MODY), we sequenced MODY cases with unknown aetiology and compared variant frequencies to large public databases. From 36 European patients, we identify two probands with novel RFX6 heterozygous nonsense variants. RFX6 protein truncating variants are enriched in the MODY discovery cohort compared to the European control population within ExAC (odds ratio = 131, P = 1 × 10-4). We find similar results in non-Finnish European (n = 348, odds ratio = 43, P = 5 × 10-5) and Finnish (n = 80, odds ratio = 22, P = 1 × 10-6) replication cohorts. RFX6 heterozygotes have reduced penetrance of diabetes compared to common HNF1A and HNF4A-MODY mutations (27, 70 and 55% at 25 years of age, respectively). The hyperglycaemia results from beta-cell dysfunction and is associated with lower fasting and stimulated gastric inhibitory polypeptide (GIP) levels. Our study demonstrates that heterozygous RFX6 protein truncating variants are associated with MODY with reduced penetrance.Maturity-onset diabetes of the young (MODY) is the most common subtype of familial diabetes. Here, Patel et al. use targeted DNA sequencing of MODY patients and large-scale publically available data to show that RFX6 heterozygous protein truncating variants cause reduced penetrance MODY.

BACKGROUND: Improving safety in care homes is becoming increasingly important. Care home residents typically have multiple physical and/or cognitive impairments, and adverse events like falls often lead to hospital attendance or admission. Developing a safety culture is associated with beneficial impacts on safety outcomes, but the complex needs of care home residents, coupled with staffing pressures in the sector, pose challenges for positive safety practices to become embedded at the individual and organisational levels. Staff training and education can positively enforce safety culture and reduce the incidence of harms, but improvement initiatives are often short lived and thorough evaluation is uncommon. This protocol outlines an evaluation of a large-scale care home improvement programme in the West Midlands. METHODS: the programme will run in 35 care homes across Walsall and Wolverhampton over 24 months, and we anticipate that 30 care homes will participate in the evaluation (n = 1500 staff). The programme will train staff and managers in service improvement techniques, with the aim of strengthening safety culture and reducing adverse safety event rates. The evaluation will use a pre-post design with mixed methods. Quantitative data will focus on: care home manager and staff surveys administered at several time points and analysis of adverse event rates. Data on hospital activity by residents at participating care homes will be compared to matched controls. Qualitative data on experience of training and the application of learning to practice will be collected via semi-structured interviews with staff (n = 48 to 64) and programme facilitators (n = 6), and staff focus groups (n = 36 to 48 staff). The primary outcome measure is the change in mean score on the safety climate domain of the Safety Attitudes Questionnaire between baseline and programme end. DISCUSSION: This mixed methods evaluation of a large-scale care home improvement programme will allow a substantial amount of qualitative and quantitative data to be collected. This will enable an assessment of the extent to which care home staff training can effectively improve safety culture, lower the incidence of adverse safety events such as falls and pressure ulcers, and potentially reduce care home resident's use of acute services.

Hyperinsulinemic hypoglycemia (HI) and congenital polycystic kidney disease (PKD) are rare, genetically heterogeneous disorders. The co-occurrence of these disorders (HIPKD) in 17 children from 11 unrelated families suggested an unrecognized genetic disorder. Whole-genome linkage analysis in five informative families identified a single significant locus on chromosome 16p13.2 (logarithm of odds score 6.5). Sequencing of the coding regions of all linked genes failed to identify biallelic mutations. Instead, we found in all patients a promoter mutation (c.-167G>T) in the phosphomannomutase 2 gene (PMM2), either homozygous or in trans with PMM2 coding mutations. PMM2 encodes a key enzyme in N-glycosylation. Abnormal glycosylation has been associated with PKD, and we found that deglycosylation in cultured pancreatic β cells altered insulin secretion. Recessive coding mutations in PMM2 cause congenital disorder of glycosylation type 1a (CDG1A), a devastating multisystem disorder with prominent neurologic involvement. Yet our patients did not exhibit the typical clinical or diagnostic features of CDG1A. In vitro, the PMM2 promoter mutation associated with decreased transcriptional activity in patient kidney cells and impaired binding of the transcription factor ZNF143. In silico analysis suggested an important role of ZNF143 for the formation of a chromatin loop including PMM2 We propose that the PMM2 promoter mutation alters tissue-specific chromatin loop formation, with consequent organ-specific deficiency of PMM2 leading to the restricted phenotype of HIPKD. Our findings extend the spectrum of genetic causes for both HI and PKD and provide insights into gene regulation and PMM2 pleiotropy.

Young-onset autoimmune diabetes associated with additional autoimmunity usually reflects a polygenic predisposition, but rare cases result from monogenic autoimmunity. Diagnosing monogenic autoimmunity is crucial for patients' prognosis and clinical management. We sought to identify novel genetic causes of autoimmunity presenting with neonatal diabetes (NDM) (diagnosis

Aims/hypothesis: the majority of infants with neonatal diabetes mellitus present with severe ketoacidosis at a median of 6 weeks. The treatment is very challenging and can result in severe neurological sequelae or death. The genetic defects that cause neonatal diabetes are present from birth. We aimed to assess if neonatal diabetes could be diagnosed earlier by measuring glucose in a dried blood spot collected on day 5 of life. Methods: in this retrospective case–control study we retrieved blood spot cards from 11 infants with genetically confirmed neonatal diabetes (median age of diagnosis 6 [range 2–112] days). For each case we also obtained one (n = 5) or two (n = 6) control blood spot cards collected on the same day. Glucose was measured on case and control blood spot cards. We established a normal range for random glucose at day 5 of life in 687 non-diabetic neonates. Results: all 11 neonates with diabetes had hyperglycaemia present on day 5 of life, with blood glucose levels ranging from 10.2 mmol/l to >30 mmol/l (normal range 3.2–6.0 mmol/l). In six of these neonates the diagnosis of diabetes was made after screening at day 5, with the latest diagnosis made at 16 weeks. Conclusions/interpretation: Neonatal diabetes can be detected on day 5 of life, preceding conventional diagnosis in most cases. Earlier diagnosis by systematic screening could lead to prompt genetic diagnosis and targeted treatment, thereby avoiding the most severe sequelae of hyperglycaemia in neonates.

In southeast New Hampshire, where reformulated gasoline was used from the 1990s to 2007, methyl tert-butyl ether (MtBE) concentrations ≥0.2 μg/L were found in water from 26.7% of 195 domestic wells sampled in 2005. Ten years later in 2015, and eight years after MtBE was banned, 10.3% continue to have MtBE. Most wells (140 of 195) had no MtBE detections (concentrations

A 2.4 kg baby boy born via Caesarian section at 35 weeks had the first onset of hypoglycemia at 2 hours of life. The infant required a glucose load of 30 mg/kg/min. Insulin level was 19.6 pmol/L (normal value 17.8-173.0) in the absence of ketosis. He was resistant to oral diazoxide but responded to octreotide infusion. The boy was found to be heterozygous for an ABCC8 nonsense mutation, p.R934. We present our experience on the use of subcutaneous octreotide for 2 years for the treatment of diazoxide resistant congenital hyperinsulinism (CHI).

Congenital hyperinsulinism (CHI) is the most common cause of neonatal persistent hypoglycemia caused by mutations in nine known genes. Early diagnosis and treatment are important to prevent brain injury. The clinical presentation and response to pharmacological therapy may vary depending on the underlying pathology. Genetic analysis is important in the diagnosis, treatment, patient follow-up, and prediction of recurrence risk within families. Our patient had severe hypoglycemia and seizure following birth. His diagnostic evaluations including genetic testing confirmed CHI. He was treated with a high-glucose infusion, high-dose diazoxide, nifedipine, and glucagon infusion. A novel homozygous mutation (p.F315I) in the KCNJ11 gene, leading to diazoxide-unresponsive CHI, was identified. Both parents were heterozygous for this mutation. Our patient’s clinical course was complicated by severe refractory hypoglycemia; he was successfully managed with sirolimus and surgical intervention was not required. Diazoxide, nifedipine, and glucagon were discontinued gradually following sirolimus therapy. The patient was discharged at 2 months of age on low-dose octreotide and sirolimus. His outpatient clinical follow-up continues with no episodes of hypoglycemia. We present a novel homozygous p.F315I mutation in the KCNJ11 gene leading to diazoxide-unresponsive CHI in a neonate. This case illustrates the challenges associated with the diagnosis and management of CHI, as well as the successful therapy with sirolimus.

Objective: Mutations in the KATP channel genes is the most common cause of congenital hyperinsulinism (CHI) of infancy. Our aim was to report the clinical and genetic characteristics, treatment modalities, and long-term prognosis of patients with CHI. Methods: Clinical and biochemical findings, operation procedures, and results of genetic analysis were retrospectively evaluated in 22 CHI patients from two pediatric endocrine centers in Turkey. Results: Seven of the patients were born large for gestational age. Hypoglycemia was diagnosed within the first 24 hours of life in 9 patients and treatment with diazoxide (n=21) and/or somatostatin (n=8) had been attempted. Seven patients (31.8%) were unresponsive to medical treatment and underwent pancreatectomy. Histological examination of the pancreas confirmed diffuse disease in 6 patients. Diabetes developed in 3 patients following pancreatectomy (10 years, 2.5 years, and immediately after operation). The remaining four patients had neither recurrence of CHI nor of diabetes during the 3.67±0.7 years of follow-up. Sequence analysis identified mutations in 12 out of 19 patients (63%). Mutations in the ABCC8 gene were the most common finding and were found in 6 out of 7 patients who underwent pancreatectomy. Other mutations included a paternally inherited KCNJ11 mutation, a homozygous HADH mutation, and a heterozygous GLUD1 mutation. Conclusion: Mutations in the ABCC8 gene were the most common cause of CHI in our cohort. These mutations were identified in 85% of patients who underwent pancreatectomy. The development of diabetes mellitus after pancreatectomy may occur at any age and these patients should be screened regularly.

Aims: Neonatal diabetes mellitus (NDM) is a rare monogenic disorder, reported to affect less than 2 cases per 100,000 infants. There are two types, permanent (PNDM) and transient (TNDM). We describe our clinical experience in determining and comparing the genetic basis of diabetes in children with onset before 6 months versus those diagnosed between 6 and 12 months of age. Methods: We reviewed medical records of children with diabetes diagnosed before 12 months of age. Genetic testing was performed in all cases. Results: 12 patients were diagnosed with diabetes before 6 months of age (PNDM = 6; TNDM = 6), and 11 patients between 6 and 12 months (all with permanent diabetes). Among children with PNDM, we identified three different KCNJ11 mutations in 5 patients, and one novel ABCC8 mutation in a single patient. Among children with TNDM, we detected a KCNJ11 and ABCC8 mutation each in a single patient and methylation abnormalities at chromosome 6q24 in 4 patients.Among children with diabetes diagnosed between 6 and 12 months, 1 patient had an INS mutation and one patient was homozygous for an SLC19A2 mutation which confirmed a diagnosis of thiamine-responsive megaloblastic anaemia syndrome. Five of the patients with an ABCC8 or KCNJ11 mutation have successfully transferred from insulin to glibenclamide whist 1 child demonstrated a partial response to sulfonylurea treatment. Conclusions: Investigating the underlying genetic basis of diabetes in children with onset before 1 year is useful for choosing the most efficient treatment, the basis of Personalized Medicine.

Background: Isolated hyperinsulinaemic hypoglycaemia (HH) commonly results from recessively inherited mutations in the ABCC8 and KCNJ11 genes that are located on chromosome 11p15.1. More rarely, HH can feature in patients with Beckwith-Wiedemann syndrome (BWS), a congenital overgrowth disorder, resulting from defects at a differentially methylated region telomeric to the K-ATP channel genes at chromosome 11p15.5. Subject: We undertook genetic testing in a patient with diazoxide-unresponsive HH diagnosed at birth. Physical examination later revealed hemihypertrophy of the right arm, a feature of BWS. Results: We identified a novel mosaic, paternally-inherited KCNJ11 mutation(s) in the patient. Further analysis confirmed uniparental disomy (UPD) of chromosome 11, which extended across the KCNJ11 gene at 11p15.1 and the BWS locus at 11p15.5. Conclusion: These results highlight the importance of considering UPD as a mechanism of disease in patients with HH and a paternally inherited K-ATP channel mutation, especially when additional syndromic features are present.

BACKGROUND: Patients with Congenital Hyperinsulinism (CHI) due to mutations in K-ATP channel genes (K-ATP CHI) are increasingly treated by conservative medical therapy without pancreatic surgery. However, the natural history of medically treated K-ATP CHI has not been described; it is unclear if the severity of recessively and dominantly inherited K-ATP CHI reduces over time. We aimed to review variation in severity and outcomes in patients with K-ATP CHI treated by medical therapy. METHODS: Twenty-one consecutively presenting patients with K-ATP CHI with dominantly and recessively inherited mutations in ABCC8/KCNJ11 were selected in a specialised CHI treatment centre to review treatment outcomes. Medical treatment included diazoxide and somatostatin receptor agonists (SSRA), octreotide and somatuline autogel. CHI severity was assessed by glucose infusion rate (GIR), medication dosage and tendency to resolution. CHI outcome was assessed by glycaemic profile, fasting tolerance and neurodevelopment. RESULTS: CHI presenting at median (range) age 1 (1, 240) days resolved in 15 (71%) patients at age 3.1(0.2, 13.0) years. Resolution was achieved both in patients responsive to diazoxide (n = 8, 57%) and patients responsive to SSRA (n = 7, 100%) with earlier resolution in the former [1.6 (0.2, 13.0) v 5.9 (1.6, 9.0) years, p = 0.08]. In 6 patients remaining on treatment, diazoxide dose was reduced in follow up [10.0 (8.5, 15.0) to 5.4 (0.5, 10.8) mg/kg/day, p = 0.003]. GIR at presentation did not correlate with resolved or persistent CHI [14.9 (10.0, 18.5) v 16.5 (13.0, 20.0) mg/kg/min, p = 0.6]. The type of gene mutation did not predict persistence; resolution could be achieved in recessively-inherited CHI with homozygous (n = 3), compound heterozygous (n = 2) and paternal mutations causing focal CHI (n = 2). Mild developmental delay was present in 8 (38%) patients; adaptive functioning assessed by Vineland Adaptive Behavior Scales questionnaire showed a trend towards higher standard deviation scores (SDS) in resolved than persistent CHI [-0.1 (-1.2, 1.6) v -1.2 (-1.7, 0.03), p = 0.1]. CONCLUSIONS: in K-ATP CHI patients managed by medical treatment only, severity is reduced over time in the majority, including those with compound heterozygous and homozygous mutations in ABCC8/KCNJ11. Severity and treatment requirement should be assessed periodically in all children with K-ATP CHI on medical therapy.

OBJECTIVE: to summarise the evidence regarding the effectiveness of integrated care interventions in reducing hospital activity. DESIGN: Umbrella review of systematic reviews and meta-analyses. SETTING: Interventions must have delivered care crossing the boundary between at least two health and/or social care settings. PARTICIPANTS: Adult patients with one or more chronic diseases. DATA SOURCES: MEDLINE, Embase, ASSIA, PsycINFO, HMIC, CINAHL, Cochrane Library (HTA database, DARE, Cochrane Database of Systematic Reviews), EPPI-Centre, TRIP, HEED, manual screening of references. OUTCOME MEASURES: Any measure of hospital admission or readmission, length of stay (LoS), accident and emergency use, healthcare costs. RESULTS: 50 reviews were included. Interventions focused on case management (n=8), chronic care model (CCM) (n=9), discharge management (n=15), complex interventions (n=3), multidisciplinary teams (MDT) (n=10) and self-management (n=5). 29 reviews reported statistically significant improvements in at least one outcome. 11/21 reviews reported significantly reduced emergency admissions (15-50%); 11/24 showed significant reductions in all-cause (10-30%) or condition-specific (15-50%) readmissions; 9/16 reported LoS reductions of 1-7�
days and 4/9 showed significantly lower A&E use (30-40%). 10/25 reviews reported significant cost reductions but provided little robust evidence. Effective interventions included discharge management with postdischarge support, MDT care with teams that include condition-specific expertise, specialist nurses and/or pharmacists and self-management as an adjunct to broader interventions. Interventions were most effective when targeting single conditions such as heart failure, and when care was provided in patients' homes. CONCLUSIONS: Although all outcomes showed some significant reductions, and a number of potentially effective interventions were found, interventions rarely demonstrated unequivocally positive effects. Despite the centrality of integrated care to current policy, questions remain about whether the magnitude of potentially achievable gains is enough to satisfy national targets for reductions in hospital activity. TRIAL REGISTRATION NUMBER: CRD42015016458.

Neonatal diabetes mellitus (NDM) can be transient (TNDM) or permanent (PNDM). Data on NDM from the Gulf region are limited to few studies on PNDM.The objective of this study was to describe the genetic and clinical spectrum of NDM and estimate its incidence in AbuDhabi, capital of the United Arab Emirate (UAE). Patients were identified from the pediatric diabetes clinics and sequencing of known NDM genes was conducted in all families. Twenty-five patients were identified. Incidence during 1985-2013 was 1:29,241 Live births. Twenty-three out of twenty-five had PNDM (incidence 1:31,900) and 2/25 had TNDM (incidence 1:350,903). Eleven out of twenty-five had extra-pancreatic features and three had pancreatic aplasia. The genetic cause was detected in 21/25 (84%). of the PNDM patients, nine had recessive EIF2AK3 mutations, six had homozygous INS mutations, two with deletion of the PTF1A enhancer, one was heterozygous for KCNJ11 mutation, one harboured a novel ABCC8 variant, and 4/21 without mutations in all known PNDM genes. One TNDM patient had a 6q24 methylation defect and another was homozygous for the INS c-331C>G mutation. This mutation also caused permanent diabetes with variable age of onset from birth to 18 years. The parents of a child with Wolcott-Rallison syndrome had a healthy girl following pre-implantation genetic diagnosis. The child with KCNJ11 mutation was successfully switched from insulin to oral sulphonylurea. The incidence of PNDM in Abu Dhabi is among the highest in the world and its spectrum is different from Europe and USA. In our cohort, genetic testing has significant implications for the clinical management.

Background: Hyperinsulinemia is the commonest cause of persistent hypoglycemia in infancy. Inactivating mutations in the genes ABCC8 and KCNJ11 are the commonest cause. Mutation in the HADH gene, which encodes the short-chain-L-3-hydroxyacyl-CoA dehydrogenase, is a rare cause. Case characteristics: Two Indian sisters who presented with hyperinsulinemic hypoglycemia of infancy. Observation/Intervention: a novel homozygous missense mutation in the HADH gene was identified in both the sisters, while the parents were found to be heterozygous carriers. Outcome: Establishment of molecular diagnosis, optimization of therapy and counseling of parents regarding risk of recurrence in future pregnancy. Messages: HADH mutations are rare causes of hypoglycemia and can be mitigated with diazoxide and appropriate dietary therapy if identified early.

Homozygous truncating mutations in the helix-loop-helix transcription factor PTF1A are a rare cause of pancreatic and cerebellar agenesis. The correlation of Ptf1a dosage with pancreatic phenotype in a mouse model suggested the possibility of finding hypomorphic PTF1A mutations in patients with pancreatic agenesis or neonatal diabetes but no cerebellar phenotype. Genome-wide single nucleotide polymorphism typing in two siblings with neonatal diabetes from a consanguineous pedigree revealed a large shared homozygous region (31 Mb) spanning PTF1A Sanger sequencing of PTF1A identified a novel missense mutation, p.P191T. Testing of 259 additional patients using a targeted next-generation sequencing assay for 23 neonatal diabetes genes detected one additional proband and an affected sibling with the same homozygous mutation. All four patients were diagnosed with diabetes at birth and were treated with insulin. Two of the four patients had exocrine pancreatic insufficiency requiring replacement therapy but none of the affected individuals had neurodevelopmental delay. Transient transfection assays of the mutant protein demonstrated a 75% reduction in transactivation activity. This study shows that the functional severity of a homozygous mutation impacts the severity of clinical features found in patients.

The most common endocrine diseases, type 1 diabetes, hyperthyroidism, and hypothyroidism, are the result of autoimmunity. Clustering of autoimmune endocrinopathies can result from polygenic predisposition, or more rarely, may present as part of a wider syndrome due to a mutation within one of seven genes. These monogenic autoimmune diseases show highly variable phenotypes both within and between families with the same mutations. The average age of onset of the monogenic forms of autoimmune endocrine disease is younger than that of the common polygenic forms, and this feature combined with the manifestation of other autoimmune diseases, specific hallmark features, or both, can inform clinicians as to the relevance of genetic testing. A genetic diagnosis can guide medical management, give an insight into prognosis, inform families of recurrence risk, and facilitate prenatal diagnoses.

AIMS/HYPOTHESIS: the pancreatic ATP-sensitive potassium (KATP) channel plays a pivotal role in linking beta cell metabolism to insulin secretion. Mutations in KATP channel genes can result in hypo- or hypersecretion of insulin, as in neonatal diabetes mellitus and congenital hyperinsulinism, respectively. To date, all patients affected by neonatal diabetes due to a mutation in the pore-forming subunit of the channel (Kir6.2, KCNJ11) are heterozygous for the mutation. Here, we report the first clinical case of neonatal diabetes caused by a homozygous KCNJ11 mutation. METHODS: a male patient was diagnosed with diabetes shortly after birth. At 5 months of age, genetic testing revealed he carried a homozygous KCNJ11 mutation, G324R, (Kir6.2-G324R) and he was successfully transferred to sulfonylurea therapy (0.2 mg kg(-1) day(-1)). Neither heterozygous parent was affected. Functional properties of wild-type, heterozygous and homozygous mutant KATP channels were examined after heterologous expression in Xenopus oocytes. RESULTS: Functional studies indicated that the Kir6.2-G324R mutation reduces the channel ATP sensitivity but that the difference in ATP inhibition between homozygous and heterozygous channels is remarkably small. Nevertheless, the homozygous patient developed neonatal diabetes, whereas the heterozygous parents were, and remain, unaffected. Kir6.2-G324R channels were fully shut by the sulfonylurea tolbutamide, which explains why the patient's diabetes was well controlled by sulfonylurea therapy. CONCLUSIONS/INTERPRETATION: the data demonstrate that tiny changes in KATP channel activity can alter beta cell electrical activity and insulin secretion sufficiently to cause diabetes. They also aid our understanding of how the Kir6.2-E23K variant predisposes to type 2 diabetes.

A major goal of molecular ecology is to identify the causes of genetic and phenotypic differentiation among populations. Population genomics is suitably poised to tackle these key questions by diagnosing the evolutionary mechanisms driving divergence in nature. Here, we set out to investigate the evolutionary processes underlying population differentiation in the Gulf pipefish, Syngnathus scovelli. We sampled approximately 50 fish from each of 12 populations distributed from the Gulf coast of Texas to the Atlantic coast of Florida and performed restriction-site-associated DNA sequencing to identify SNPs throughout the genome. After imposing quality and stringency filters, we selected a panel of 6348 SNPs present in all 12 populations, 1753 of which were not physically linked. We identified a genome-wide pattern of isolation by distance, in addition to a more substantial genetic break separating populations in the Gulf of Mexico from those in the Atlantic. We also used several divergence outlier approaches and tests for genotype-environment correlations to identify 400 SNPs putatively involved in local adaptation. Patterns of phenotypic differentiation and variation diverged from the overall genomic pattern, suggesting that selection, phenotypic plasticity or demographic factors may be shaping phenotypes in distinct populations. Overall, our results suggest that population divergence is driven by a variety of factors in S. scovelli, including neutral processes and selection on multiple traits.

BACKGROUND: Hyperglycemia in premature infants is usually thought to reflect inadequate pancreatic development rather than monogenic neonatal diabetes. No studies, to our knowledge, have investigated the prevalence of monogenic forms of diabetes in preterm infants. METHODS: We studied 750 patients with diabetes diagnosed before 6 months of age. We compared the genetic etiology and clinical characteristics of 146 preterm patients born 32 weeks). Prematurity should not prevent referral for genetic testing as 37% have a potassium channel mutation and as a result can get improved control by replacing insulin with sulphonylurea therapy.

AIMS: Mutations in the KCNJ11 gene, which encodes the Kir6.2 subunit of the pancreatic KATP channel, cause neonatal diabetes. KCNJ11 is also expressed in the brain, and ~ 20% of those affected have neurological features, which may include features suggestive of psychiatric disorder. No previous studies have systematically characterized the psychiatric morbidity in people with KCNJ11 neonatal diabetes. We aimed to characterize the types of psychiatric disorders present in children with KCNJ11 mutations, and explore their impact on families. METHODS: the parents and teachers of 10 children with neonatal diabetes due to KCNJ11 mutations completed the Strengths and Difficulties Questionnaire and the Development and Wellbeing Assessment. Strengths and Difficulties Questionnaire scores were compared with normative data. Diagnoses from the Development and Wellbeing Assessment were compared with known clinical diagnoses. RESULTS: Strengths and Difficulties Questionnaire scores indicated high levels of psychopathology and impact. Psychiatric disorder(s) were present in all six children with the V59M or R201C mutation, and the presence of more than one psychiatric disorder was common. Only two children had received a formal clinical diagnosis, with a further one awaiting assessment, and the coexistence of more than one psychiatric disorder had been missed. Neurodevelopmental (attention deficit hyperactivity disorder and autism) and anxiety disorders predominated. CONCLUSIONS: Systematic assessment using standardized validated questionnaires reveals a range of psychiatric morbidity in children with KCNJ11 neonatal diabetes. This is under-recognized clinically and has a significant impact on affected children and their families. An integrated collaborative approach to clinical care is needed to manage the complex needs of people with KCNJ11 neonatal diabetes.

INTRODUCTION: Open chest surgery (thoracotomy) is considered the most painful of surgical procedures. Forceful wound retraction, costochondral dislocation, posterior costovertebral ligament disruption, intercostal nerve trauma and wound movement during respiration combine to produce an acute, severe postoperative pain insult and persistent chronic pain many months after surgery is common. Three recent systematic reviews conclude that unilateral continuous paravertebral blockade (PVB) provides analgesia at least equivalent to thoracic epidural blockade (TEB) in the postoperative period, has a lower failure rate, and symptom relief that lasted months. Crucially, PVB may reduce the development of subsequent chronic pain by intercostal nerve protection or decreased nociceptive input. The overall aim is to determine in patients who undergo thoracotomy whether perioperative PVB results in reducing chronic post-thoracotomy pain (CPTP) compared with TEB. This pilot study will evaluate feasibility of a substantive trial. METHODS AND ANALYSIS: TOPIC is a randomised controlled trial comparing the effectiveness of TEB and PVB in reducing CPTP. This is a pilot study to evaluate feasibility of a substantive trial and study processes in 2 adult thoracic centres, Heart of England NHS Foundation Trust (HEFT) and University Hospital of South Manchester NHS Foundation Trust (UHSM). The primary objective is to establish the number of patients randomised as a proportion of those eligible. Secondary objectives include evaluation of study processes. Analyses of feasibility and patient-reported outcomes will primarily take the form of simple descriptive statistics and where appropriate, point estimates of effects sizes and associated 95% CIs. ETHICS AND DISSEMINATION: the study has obtained ethical approval from NHS Research Ethics Committee (REC number 14/EM/1280). Dissemination plan includes: informing patients and health professionals; engaging multidisciplinary professionals to support a proposal of a definitive trial and submission for a full HTA application dependent on the success of the study. TRIAL REGISTRATION NUMBER: ISRCTN45041624; Pre-results.

AIMS/HYPOTHESIS: the finding that patients with diabetes due to potassium channel mutations can transfer from insulin to sulfonylureas has revolutionised the management of patients with permanent neonatal diabetes. The extent to which the in vitro characteristics of the mutation can predict a successful transfer is not known. Our aim was to identify factors associated with successful transfer from insulin to sulfonylureas in patients with permanent neonatal diabetes due to mutations in KCNJ11 (which encodes the inwardly rectifying potassium channel Kir6.2). METHODS: We retrospectively analysed clinical data on 127 patients with neonatal diabetes due to KCNJ11 mutations who attempted to transfer to sulfonylureas. We considered transfer successful when patients completely discontinued insulin whilst on sulfonylureas. All unsuccessful transfers received ≥0.8 mg kg(-1) day(-1) glibenclamide (or the equivalent) for >4 weeks. The in vitro response of mutant Kir6.2/SUR1 channels to tolbutamide was assessed in Xenopus oocytes. For some specific mutations, not all individuals carrying the mutation were able to transfer successfully; we therefore investigated which clinical features could predict a successful transfer. RESULTS: in all, 112 out of 127 (88%) patients successfully transferred to sulfonylureas from insulin with an improvement in HbA1c from 8.2% (66 mmol/mol) on insulin, to 5.9% (41 mmol/mol) on sulphonylureas (p = 0.001). The in vitro response of the mutation to tolbutamide determined the likelihood of transfer: the extent of tolbutamide block was 73% did transfer successfully. The few patients with these mutations who could not transfer had a longer duration of diabetes than those who transferred successfully (18.2 vs 3.4 years, p = 0.032). There was no difference in pre-transfer HbA1c (p = 0.87), weight-for-age z scores (SD score; p = 0.12) or sex (p = 0.17). CONCLUSIONS/INTERPRETATION: Transfer from insulin is successful for most KCNJ11 patients and is best predicted by the in vitro response of the specific mutation and the duration of diabetes. Knowledge of the specific mutation and of diabetes duration can help predict whether successful transfer to sulfonylureas is likely. This result supports the early genetic testing and early treatment of patients with neonatal diabetes aged under 6 months.

Distinguishing patients with monogenic diabetes from those with type 1 diabetes (T1D) is important for correct diagnosis, treatment, and selection of patients for gene discovery studies. We assessed whether a T1D genetic risk score (T1D-GRS) generated from T1D-associated common genetic variants provides a novel way to discriminate monogenic diabetes from T1D. The T1D-GRS was highly discriminative of proven maturity-onset diabetes of young (MODY) (n = 805) and T1D (n = 1,963) (receiver operating characteristic area under the curve 0.87). A T1D-GRS of >0.280 (>50th T1D centile) was indicative of T1D (94% specificity, 50% sensitivity). We then analyzed the T1D-GRS of 242 white European patients with neonatal diabetes (NDM) who had been tested for all known NDM genes. Monogenic NDM was confirmed in 90, 59, and 8% of patients with GRS <5th T1D centile, 50–75th T1D centile, and >75th T1D centile, respectively. Applying a GRS 50th T1D centile cutoff in 48 NDM patients with no known genetic cause identified those most likely to have a novel monogenic etiology by highlighting patients with probable early-onset T1D (GRS >50th T1D centile) who were diagnosed later and had less syndromic presentation but additional autoimmune features compared with those with proven monogenic NDM. The T1D-GRS is a novel tool to improve the use of biomarkers in the discrimination of monogenic diabetes from T1D.

Unlike other congenital fatty acid oxidation defects, short-chain L-3-hydroxyacyl-CoA (SCHAD, HADH) deficiency is characterised by hypoglycemia with hyperinsulinism in the neonatal or infancy periods. The long-term and detailed clinical progression of the disease is largely unknown with almost 40 patients reported and only a few patients described clinically. We present clinical and laboratory findings together with the long-term clinical course of a case with a deep intronic HADH splicing mutation (c.636+471G>T) causing neonatal-onset hyperinsulinemic hypoglycemia with mild progression.

Background: Inheritance of two pathogenic ABCC8 alleles typically causes severe congenital hyperinsulinism. We describe a girl and her father, both homozygous for the same ABCC8 mutation, who presented with unusual phenotypes. Methods: Single nucleotide polymorphism microarray and Sanger sequencing were performed. Western blot, rubidium efflux, and patch clamp recordings interrogated the expression and activity of the mutant protein. Results: a 16-month-old girl of consanguineous descent manifested hypoglycemia. She had dysregulation of insulin secretion, with postprandial hyperglycemia followed by hypoglycemia. Microarray revealed homozygosity for the regions encompassing KCNJ11 and ABCC8. Her father had developed diabetes at 28 years of age. Sequencing of ABCC8 identified a homozygous missense mutation, p.R1419H, in both individuals. Functional studies showed absence of working KATP channels. Conclusion: This is the first description of a homozygous p.R1419H mutation. Our findings highlight that homozygous loss-of-function mutations of ABCC8 do not necessarily translate into early-onset severe hyperinsulinemia.

Neonatal diabetes is a highly genetically heterogeneous disorder. There are over 20 distinct syndromic and non-syndromic forms, including dominant, recessive and X-linked subtypes. Biallelic truncating or mis-sense mutations in the DNA-binding domain of the RFX6 transcription factor cause an autosomal recessive, syndromic form of neonatal diabetes previously described as Mitchell-Riley syndrome. In all, eight cases have been reported, with the age at onset of diabetes in the first 2 weeks of life. Here we report two individuals born to double first cousins in whom intestinal atresias consistent with a diagnosis of Mitchell-Riley syndrome were diagnosed at birth, but in whom diabetes did not present until the ages of 3 and 6 years. Novel compound heterozygous RFX6 nonsense mutations (p.Arg726X/p.Arg866X) were identified at the 3′ end of the gene. The later onset of diabetes in these patients may be due to incomplete inactivation of RFX6. Genetic testing for RFX6 mutations should be considered in patients presenting with intestinal atresias in the absence of neonatal diabetes.

Neonatal diabetes is a highly genetically heterogeneous disorder. There are over 20 distinct syndromic and non-syndromic forms, including dominant, recessive and X-linked subtypes. Biallelic truncating or mis-sense mutations in the DNA-binding domain of the RFX6 transcription factor cause an autosomal recessive, syndromic form of neonatal diabetes previously described as Mitchell-Riley syndrome. In all, eight cases have been reported, with the age at onset of diabetes in the first 2 weeks of life. Here we report two individuals born to double first cousins in whom intestinal atresias consistent with a diagnosis of Mitchell-Riley syndrome were diagnosed at birth, but in whom diabetes did not present until the ages of 3 and 6 years. Novel compound heterozygous RFX6 nonsense mutations (p.Arg726X/p.Arg866X) were identified at the 3' end of the gene. The later onset of diabetes in these patients may be due to incomplete inactivation of RFX6. Genetic testing for RFX6 mutations should be considered in patients presenting with intestinal atresias in the absence of neonatal diabetes.

BACKGROUND: Neonatal diabetes mellitus (NDM) is a rare form of monogenic diabetes and usually presents in the first 6 months of life. We aimed to describe the clinical characteristics and molecular genetics of a large Turkish cohort of NDM patients from a single centre and estimate an annual incidence rate of NDM in South-Eastern Anatolian region of Turkey. DESIGN AND METHODS: NDM patients presenting to Diyarbakir Children State Hospital between 2010 and 2013, and patients under follow-up with presumed type 1 diabetes mellitus, with onset before 6 months of age were recruited. Molecular genetic analysis was performed. RESULTS: Twenty-two patients (59% males) were diagnosed with NDM (TNDM-5; PNDM-17). Molecular genetic analysis identified a mutation in 20 (95%) patients who had undergone a mutation analysis. In transient neonatal diabetes (TNDM) patients, the genetic cause included chromosome 6q24 abnormalities (n=3), ABCC8 (n=1) and homozygous INS (n=1). In permanent neonatal diabetes (PNDM) patients, homozygous GCK (n=6), EIF2AK3 (n=3), PTF1A (n=3), and INS (n=1) and heterozygous KCNJ11 (n=2) mutations were identified. Pancreatic exocrine dysfunction was observed in patients with mutations in the distal PTF1A enhancer. Both patients with a KCNJ11 mutation responded to oral sulphonylurea. A variable phenotype was associated with the homozygous c.-331C>A INS mutation, which was identified in both a PNDM and TNDM patient. The annual incidence of PNDM in South-East Anatolian region of Turkey was one in 48 000 live births. CONCLUSIONS: Homozygous mutations in GCK, EIF2AK3 and the distal enhancer region of PTF1A were the commonest causes of NDM in our cohort. The high rate of detection of a mutation likely reflects the contribution of new genetic techniques (targeted next-generation sequencing) and increased consanguinity within our cohort.

Hyperinsulinaemic hypoglycaemia (HH) is characterised by inappropriate insulin secretion and is the most common cause for persistent neonatal hypoglycaemia. The only treatment available for medically unresponsive hypoglycaemia is a near-total pancreatectomy. A neonate with severe HH, due to a homozygous ABCC8 mutation, was not responsive to treatment with maximal doses of diazoxide and subcutaneous daily octreotide, and underwent a near-total pancreatectomy; however, hypoglycaemia persisted. Introduction of sirolimus, an mTOR (mammalian target of rapamycin) inhibitor, obviated the requirement for glucose infusion. Euglycaemia was achieved with no significant adverse events from the drug. Sirolimus therapy was ceased at 13 months of age. No episodes of persistent hypoglycaemia were observed after cessation of sirolimus. This report demonstrates the successful use of sirolimus for persistent hypoglycaemia in the critically ill infant post pancreatectomy. Sirolimus could be considered in patients with severe HH not responsive to conventional medical and surgical therapy. However, the long-term efficacy and safety with this immunosuppressive drug in very young patients are not assured.

BACKGROUND: Hyperinsulinaemic hypoglycaemia (HH) is a group of clinically and genetically heterogeneous disorders characterized by unregulated insulin secretion. Abnormalities in nine different genes (ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A, UCP2 and HNF1A) have been reported in HH, the most common being ABCC8 and KCNJ11. We describe the genetic aetiology and phenotype of Iranian patients with HH. METHODS: Retrospective clinical, biochemical and genetic information was collected on 23 patients with biochemically confirmed HH. Mutation analysis was carried out for the ATP-sensitive potassium (K(ATP)) channel genes (ABCC8 and KCNJ11), GLUD1, GCK, HADH and HNF4A. RESULTS: 78% of the patients were identified to have a genetic cause for HH. 48% of patients had mutation in HADH, whilst ABCC8/KCNJ11 mutations were identified in 30% of patients. Among the diazoxide-responsive patients (18/23), mutations were identified in 72%. These include two novel homozygous ABCC8 mutations. of the five patients with diazoxide-unresponsive HH, three had homozygous ABCC8 mutation, one had heterozygous ABCC8 mutation inherited from an unaffected father and one had homozygous KCNJ11 mutation. 52% of children in our cohort were born to consanguineous parents. Patients with ABCC8/KCNJ11 mutations were noted to be significantly heavier than those with HADH mutation (p = 0.002). Our results revealed neurodevelopmental deficits in 30% and epilepsy in 52% of all patients. CONCLUSIONS: to the best of our knowledge, this is the first study of its kind in Iran. We found disease-causing mutations in 78% of HH patients. The predominance of HADH mutation might be due to a high incidence of consanguineous marriage in this population. Further research involving a larger cohort of HH patients is required in Iranian population.

Congenital hyperinsulinism causes profound hypoglycemia, which may persist or resolve spontaneously. Among 13 children with congenital hyperinsulinism, elevated incretin hormone concentrations were detected in 2 with atypical, persistent disease. We suggest that incretin biomarkers may identify these patients, and that elevated hormone levels may contribute to their pathophysiology.

Background: Wolcott-Rallison syndrome (WRS) is caused by recessive EIF2AK3 mutations and characterized by early-onset diabetes and skeletal dysplasia. Hepatic dysfunction has been reported in 60% of patients. Aims: to describe a cohort of WRS patients and discuss the pattern and management of their liver disease. Methods: Detailed phenotyping and direct sequencing of EIF2AK3 gene were conducted in all patients. Results: Twenty-eight genetically confirmed patients (67% male; mean age 4.6 years) were identified. 17 different EIF2AK3 mutations were detected, of which 2 were novel. The p.S991N mutation was associated with prolonged survival and p.I650T with delayed onset. All patients presented before 25 months with diabetes with variation in the frequency and severity of 10 other features. Liver disease, first manifested as non-autoimmune hepatitis, was the commonest extra-pancreatic feature identified in 85.7% (24/28). 22/24 had at least one episode of acute hepatic failure which was the cause of death in all deceased patients (13/28). One child was treated by liver transplantation and had no liver disease and better diabetes control for the following 6 years. Conclusions: Liver disease in WRS is more frequent than previously described and carries high mortality. The first experience with liver transplantation in WRS is encouraging.

Hyperinsulinaemic hypoglycaemia (HH) is caused by mutations in the key genes involved in regulation of insulin secretion from the pancreatic β-cells and mutations in ABCC8 and KCNJ11 are the most common causes of HH. Mutations in HADH (which encodes the enzyme 3-hydroxyacyl-CoA dehydrogenase) are a rare cause of HH. We report three siblings (21, 9, and 7 years old) from a consanguineous Saudi family with HH due to a homozygous mutation in HADH. All three siblings presented with HH in the 1st year of life. HH responded well to medical therapy (diazoxide/octreotide) although the 1st sibling suffered neurological damage. The protein load test revealed protein sensitivity in the 21-year-old proband, the oldest reported patient with HH secondary to a HADH mutation. Genetic analysis revealed a homozygous HADH splicing mutation (c.133-1G>A) in all three siblings. HADH mutations can present in later infancy or childhood with severe HH that is usually diazoxide responsive. Severe neurological complications such as epilepsy and developmental delay can be associated with HADH mutations. This is the 1st report of HH due to HADH mutation in an adult suggesting that HH could persist into adulthood possibly becoming milder over the years.

Introduction: Hyperinsulinaemic hypoglycaemia (HH) is the most common cause of severe and persistent hypoglycaemia in neonates. The treatment of severe diazoxide unresponsive HH involves near total pancreatectomy. Mammalian target of rapamycin (mTOR) is a protein kinase that regulates cellular proliferation. mTOR inhibitors are used in cancer patients and recently found to be effective in the treatment of insulinoma and HH patients. Case: a 36 weeks large for gestational age neonate presented with severe hypoglycaemia on day 1 of life. The hypoglycaemia screen confirmed HH and genetic testing revealed compound heterozygous ABCC8 mutation, confirming diffuse disease. He was unresponsive to the maximal dose of diazoxide (15 mg/kg/day), hence needed treatment with higher concentration of intravenous glucose (25 mg/kg/min), intravenous glucagon and subcutaneous octreotide (30 μg/kg/day) infusions to maintain normoglycaemia. Sirolimus, a mTOR inhibitor, was commenced at 9 weeks of age following which he showed a marked improvement in his glycaemic control. After 4 weeks of sirolimus therapy, he was discharged home on subcutaneous octreotide injection (20 μg/kg/day) and oral sirolimus, thereby avoiding the need for a near total pancreatectomy. Conclusion: We report the first case of compound heterozygous ABCC8 mutation causing severe diffuse HH that responded to therapy with a mTOR inhibitor.

BACKGROUND: Traditional genetic testing focusses on analysis of one or a few genes according to clinical features; this approach is changing as improved sequencing methods enable simultaneous analysis of several genes. Neonatal diabetes is the presenting feature of many discrete clinical phenotypes defined by different genetic causes. Genetic subtype defines treatment, with improved glycaemic control on sulfonylurea treatment for most patients with potassium channel mutations. We investigated the effect of early, comprehensive testing of all known genetic causes of neonatal diabetes. METHODS: in this large, international, cohort study, we studied patients with neonatal diabetes diagnosed with diabetes before 6 months of age who were referred from 79 countries. We identified mutations by comprehensive genetic testing including Sanger sequencing, 6q24 methylation analysis, and targeted next-generation sequencing of all known neonatal diabetes genes. FINDINGS: Between January, 2000, and August, 2013, genetic testing was done in 1020 patients (571 boys, 449 girls). Mutations in the potassium channel genes were the most common cause (n=390) of neonatal diabetes, but were identified less frequently in consanguineous families (12% in consanguineous families vs 46% in non-consanguineous families; p4 years; p

Background: Wolfram syndrome is an autosomal recessive disorder caused by mutations in the WFS1 gene. Clinical heterogeneity has been reported both within and between families with WFS1 mutations. Subjects: the first case was diagnosed with insulin-dependent diabetes mellitus with positive for pancreatic autoantibodies and had a ketoacidotic attack in the follow-up period. The second case presented initially with optic atrophy and was diagnosed with behavioral and psychiatric problems at an early age. The third case had early onset insulin-dependent diabetes with multiple anomalies and congenital hypothyroidism. Many of these features have not been reported previously in patients with Wolfram syndrome. In all three patients homozygous mutations in WFS1 were identified. Conclusion: Wolfram syndrome is a disease where the characteristic features may present at different times. A diagnosis of Wolfram syndrome should therefore be considered even in the absence of the full spectrum of clinical features.

Hyperinsulinemic hypoglycemia (HH) is the commonest cause of persistent hypoglycemia in the neonatal and infancy periods. Mutations in the ABCC8 and KCNJ11 genes, which encode subunits of the ATP- sensitive potassium channel in the pancreatic beta cell, are identified in approximately 50% of these patients. The first-line drug in the treatment of HH is diazoxide. Octreotide and glucagon can be used in patients who show no response to diazoxide. Nifedipine, a calcium-channel blocker, has been shown to be an effective treatment in a small number of patients with diazoxide-unresponsive HH. We report a HH patient with a homozygous ABCC8 mutation (p.W1339X) who underwent a near- total pancreatectomy at 2 months of age due to a lack of response to diazoxide and octreotide treatment. Severe hypoglycemic attacks continued following surgery, while the patient was being treated with octreotide. These attacks resolved when nifedipine was introduced. Whilst our patient responded well to nifedipine, the dosage could not be increased to 0.75 mg/kg/day due to development of hypotension, a reported side effect of this drug. Currently, our patient, now aged 4 years, is receiving a combination of nifedipine and octreotide treatment. He is under good control and shows no side effects. In conclusion, nifedipine treatment can be started in patients with HH who show a poor response to diazoxide and octreotide treatment. © Journal of Clinical Research in Pediatric Endocrinology, Published by Galenos Publishing.

BACKGROUND: Hyperinsulinemic hypoglycemia (HH), characterized by unregulated insulin secretion, is an important cause of persistent and severe hypoglycemia. The biochemical picture of HH is hypoketotic hypo-fatty-acidemic hypoglycemia along with elevated serum insulin. Not infrequently, serum insulin might be undetectable in HH despite the presence of evidence of insulin action (suppressed ketogenesis and lipolysis). However, autonomous activity of the downstream insulin signaling pathway without the presence of the ligand (insulin) will give rise to the same clinical and biochemical picture, apart from undetectable serum insulin/C-peptide. AKT2, a serine/threonine protein kinase, is involved downstream to the insulin receptor in mediating the physiological effects of insulin. AIM: We describe the second report of an activating AKT2 mutation leading to hypoinsulinemic hypoketotic hypoglycemia. PATIENTS AND METHODS: the proband presented with hemihypertrophy and symptomatic hypoglycemia. Investigations confirmed evidence of insulin action, despite absence of detectable serum insulin on multiple occasions. Molecular genetic testing for common causes of HH (ABCC8, KCNJ11, and GLUD1) was negative. Sequencing of AKT2 identified a de novo mosaic c.49G→A (p.E17K) mutation, consistent with the clinical and biochemical phenotype. CONCLUSIONS: This is the second report of an activating AKT2 mutation leading to hypoinsulinemic hypoketotic hypo-fatty-acidemic hypoglycemia. In patients presenting a clinical and biochemical picture of HH with undetectable serum insulin, consideration of autonomous activation of the downstream insulin signaling pathway should be made.

Monogenic causes of autoimmunity provide key insights into the complex regulation of the immune system. We report a new monogenic cause of autoimmunity resulting from de novo germline activating STAT3 mutations in five individuals with a spectrum of early-onset autoimmune disease, including type 1 diabetes. These findings emphasize the critical role of STAT3 in autoimmune disease and contrast with the germline inactivating STAT3 mutations that result in hyper IgE syndrome.

CONTEXT: Congenital hyperinsulinism (CHI) has two main histological types: diffuse and focal. Heterozygous paternally inherited ABCC8/KCNJ11 mutations (depending upon whether recessive or dominant acting and occurrence of somatic maternal allele loss) can give rise to either phenotype. However, the relative proportion of these two phenotypes in a large cohort of CHI patients due to paternally inherited heterozygous ABCC8/KCNJ11 mutations has not been reported. OBJECTIVE: the purpose of this study is to highlight the variable clinical phenotype and to characterise the distribution of diffuse and focal disease in a large cohort of CHI patients due to paternally inherited heterozygous ABCC8/KCNJ11 mutations. DESIGN: a retrospective chart review of the CHI patients due to heterozygous paternally inherited ABCC8/KCNJ11 mutations from 2000 to 2013 was conducted. RESULTS: Paternally inherited heterozygous ABCC8/KCNJ11 mutations were identified in 53 CHI patients. of these, 18 (34%) either responded to diazoxide or resolved spontaneously. Fluorine-18 l-3, 4-dihydroxyphenylalanine positron emission tomography computerised tomography 18F DOPA-PET CT) scanning in 3/18 children showed diffuse disease. The remaining 35 (66%) diazoxide-unresponsive children either had pancreatic venous sampling (n=8) or 18F DOPA-PET CT (n=27). Diffuse, indeterminate and focal disease was identified in 13, 1 and 21 patients respectively. Two patients with suspected diffuse disease were identified to have focal disease on histology. CONCLUSIONS: Paternally inherited heterozygous ABCC8/KCNJ11 mutations can manifest as a wide spectrum of CHI with variable 18F DOPA-PET CT/histological findings and clinical outcomes. Focal disease was histologically confirmed in 24/53 (45%) of CHI patients with paternally inherited heterozygous ABCC8/KCNJ11 mutations.

OBJECTIVE: Congenital hyperinsulinism (CHI) is the commonest cause of hyperinsulinaemic hypoglycaemia in the neonatal, infancy and childhood periods. Its clinical presentation, histology and underlying molecular biology are extremely heterogeneous. The aim of this study was to describe the clinical characteristics, analyse the genotype-phenotype correlations and describe the treatment outcome of Turkish CHI patients. DESIGN AND METHODS: a total of 35 patients with CHI were retrospectively recruited from four large paediatric endocrine centres in Turkey. Detailed clinical, biochemical and genotype information was collected. RESULTS: Diazoxide unresponsiveness was observed in nearly half of the patients (n=17; 48.5%). Among diazoxide-unresponsive patients, mutations in ABCC8/KCNJ11 were identified in 16 (94%) patients. Among diazoxide-responsive patients (n=18), mutations were identified in two patients (11%). Genotype-phenotype correlation revealed that mutations in ABCC8/KCNJ11 were associated with an increased birth weight and early age of presentation. Five patients had p.L1171fs (c.3512del) ABCC8 mutations, suggestive of a founder effect. The rate of detection of a pathogenic mutation was higher in consanguineous families compared with non-consanguineous families (87.5 vs 21%; P

The GATA family zinc finger transcription factors GATA4 and GATA6 are known to play important roles in the development of the pancreas. In mice, both Gata4 and Gata6 are required for pancreatic development. In humans, GATA6 haploinsufficiency can cause pancreatic agenesis and heart defects. Congenital heart defects also are common in patients with GATA4 mutations and deletions, but the role of GATA4 in the developing human pancreas is unproven. We report five patients with deletions (n = 4) or mutations of the GATA4 gene who have diabetes and a variable exocrine phenotype. In four cases, diabetes presented in the neonatal period (age at diagnosis 1-7 days). A de novo GATA4 missense mutation (p.N273K) was identified in a patient with complete absence of the pancreas confirmed at postmortem. This mutation affects a highly conserved residue located in the second zinc finger domain of the GATA4 protein. In vitro studies showed reduced DNA binding and transactivational activity of the mutant protein. We show that GATA4 mutations/deletions are a cause of neonatal or childhood-onset diabetes with or without exocrine insufficiency. These results confirm a role for GATA4 in normal development of the human pancreas.

BACKGROUND: Hepatocyte nuclear factor 4α (HNF4A) is a member of the nuclear receptor family of ligand-activated transcription factors. HNF4A mutations cause hyperinsulinaemic hypoglycaemia in early life and maturity-onset diabetes of the young. Regular screening of HNF4A mutation carriers using the oral glucose tolerance test has been recommended to diagnose diabetes mellitus at an early stage. Glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide are incretin hormones, responsible for up to 70% of the secreted insulin after a meal in healthy individuals. We describe, for the first time, gradual alteration of glucose homeostasis in a patient with HNF4A mutation after resolution of hyperinsulinaemic hypoglycaemia, on serial oral glucose tolerance testing. We also measured the incretin response to a mixed meal in our patient. CASE REPORT: Our patient was born with macrosomia and developed hyperinsulinaemic hypoglycaemia in the neonatal period. Molecular genetic analysis confirmed HNF4A mutation (p.M116I, c.317G>A) as an underlying cause of hyperinsulinaemic hypoglycaemia. Serial oral glucose tolerance testing, after the resolution of hyperinsulinaemic hypoglycaemia, confirmed the diagnosis of maturity-onset diabetes of the young at the age of 10 years. Interestingly, the intravenous glucose tolerance test revealed normal glucose disappearance rate and first-phase insulin secretion. Incretin hormones showed a suboptimal rise in response to the mixed meal, potentially explaining the discrepancy between the oral glucose tolerance test and the intravenous glucose tolerance test. CONCLUSIONS: Maturity-onset diabetes of the young can develop as early as the first decade of life in persons with an HNF4A mutation. Impaired incretin response might be contributory in the early stages of HNF4A maturity-onset diabetes of the young.

CONTEXT: Octreotide, a somatostatin analog, is commonly used in diazoxide unresponsive congenital hyperinsulinism (CHI) patients as a second-line therapy. OBJECTIVE: the aims of this study were to evaluate the dose range, side effects, and long-term follow-up of octreotide therapy in a large cohort of CHI patients. SETTING: the study was conducted at an international referral center for the management of CHI. PATIENTS: Twenty-eight (17 males) diazoxide unresponsive CHI patients (15 biallelic and 10 monoallelic ATP sensitive potassium channel mutation) managed with daily multidose octreotide therapy between 2001 and 2013 participated in the study. MAIN OUTCOME MEASURES: Regular follow-up of auxology, growth factors (serum IGF-1 and IGF binding protein 3 levels), thyroid functions, liver function tests, and hepatobiliary ultrasonography were measured. RESULTS: the median age of CHI diagnosis was 1 week (range 1-80 wk). The mean (±SD) dose of octreotide required was 17.8 (±7.5) μg/kg · d (range 7.5-30 μg/kg · d). The mean (±SD) duration of follow-up on octreotide therapy was 52.4 (±33.8) months (range 6 mo to 9.5 y). Elevation of liver enzymes was the most prevalent side effect (n = 13; 46.4%), which resolved spontaneously. Gallbladder pathology was detected in nine patients (32%). Mean (±SD) duration of octreotide therapy before the development of gallbladder pathology was 4.3 (±4.6 mo), whereas 19 patients were free of gallstones after a follow-up of 53.6 ± 32.9 months on octreotide therapy. There was no relationship between the dose or the duration of octreotide therapy and development of gallbladder pathology or liver dysfunction. CONCLUSIONS: Transient elevation of liver enzymes and asymptomatic gallbladder pathology were the most prevalent long-term side effects of octreotide therapy. There was no correlation between the dose or the duration of octreotide therapy and development of liver dysfunction and gallbladder pathology.

CONTEXT: Congenital hyperinsulinism (CHI), the commonest cause of persistent hypoglycaemia, has two main histological subtypes: diffuse and focal. Diffuse CHI, if medically unresponsive, is managed with near-total pancreatectomy. Post-pancreatectomy, in addition to persistent hypoglycaemia, there is a very high risk of diabetes mellitus and pancreatic exocrine insufficiency. SETTING: International referral centre for the management of CHI. PATIENTS: Medically unresponsive diffuse CHI patients managed with near-total pancreatectomy between 1994 and 2012. INTERVENTION: Near-total pancreatectomy. MAIN OUTCOME MEASURES: Persistent hypoglycaemia post near-total pancreatectomy, insulin-dependent diabetes mellitus, clinical and biochemical (faecal elastase 1) pancreatic exocrine insufficiency. RESULTS: of more than 300 patients with CHI managed during this time period, 45 children had medically unresponsive diffuse disease and were managed with near-total pancreatectomy. After near-total pancreatectomy, 60% of children had persistent hypoglycaemia requiring medical interventions. The incidence of insulin dependent diabetes mellitus was 96% at 11 years after surgery. Thirty-two patients (72%) had biochemical evidence of severe pancreatic exocrine insufficiency (Faecal elastase 1

Many patients with monogenic diabetes are missed or misclassified. Herein, we report a 28-year-old Indian female who developed diabetes at the age of 3 months. An audit of our type 1 diabetes database led to her genetic testing. A KCNJ11 mutation was identified and she was successfully switched to sulphonylurea.

Many patients with monogenic diabetes are missed or misclassified. Herein, we report a 28-year-old Indian female who developed diabetes at the age of 3 months. An audit of our type 1 diabetes database led to her genetic testing. A KCNJ11 mutation was identified and she was successfully switched to sulphonylurea.

Mutations in glucokinase (GCK) cause a spectrum of glycemic disorders. Heterozygous loss-of-function mutations cause mild fasting hyperglycemia irrespective of mutation severity due to compensation from the unaffected allele. Conversely, homozygous loss-of-function mutations cause permanent neonatal diabetes requiring lifelong insulin treatment. This study aimed to determine the relationship between in vitro mutation severity and clinical phenotype in a large international case series of patients with homozygous GCK mutations. Clinical characteristics for 30 patients with diabetes due to homozygous GCK mutations (19 unique mutations, including 16 missense) were compiled and assigned a clinical severity grade (CSG) based on birth weight and age at diagnosis. The majority (28 of 30) of subjects were diagnosed before 9 months, with the remaining two at 9 and 15 years. These are the first two cases of a homozygous GCK mutation diagnosed outside infancy. Recombinant mutant GCK proteins were analyzed for kinetic and thermostability characteristics and assigned a relative activity index (RAI) or relative stability index (RSI) value. Six of 16 missense mutations exhibited severe kinetic defects (RAI ≤ 0.01). There was no correlation between CSG and RAI (r(2) = 0.05, P = 0.39), indicating that kinetics alone did not explain the phenotype. Eighty percent of the remaining mutations showed reduced thermostability, the exceptions being the two later-onset mutations which exhibited increased thermostability. Comparison of CSG with RSI detected a highly significant correlation (r(2) = 0.74, P = 0.002). We report the largest case series of homozygous GCK mutations to date and demonstrate that they can cause childhood-onset diabetes, with protein instability being the major determinant of mutation severity.

The contribution of cis-regulatory mutations to human disease remains poorly understood. Whole-genome sequencing can identify all noncoding variants, yet the discrimination of causal regulatory mutations represents a formidable challenge. We used epigenomic annotation in human embryonic stem cell (hESC)-derived pancreatic progenitor cells to guide the interpretation of whole-genome sequences from individuals with isolated pancreatic agenesis. This analysis uncovered six different recessive mutations in a previously uncharacterized ~400-bp sequence located 25 kb downstream of PTF1A (encoding pancreas-specific transcription factor 1a) in ten families with pancreatic agenesis. We show that this region acts as a developmental enhancer of PTF1A and that the mutations abolish enhancer activity. These mutations are the most common cause of isolated pancreatic agenesis. Integrating genome sequencing and epigenomic annotation in a disease-relevant cell type can thus uncover new noncoding elements underlying human development and disease.

Hyperinsulinemic hypoglycemia is the most common cause of severe, persistent neonatal hypoglycemia. The treatment of hyperinsulinemic hypoglycemia that is unresponsive to diazoxide is subtotal pancreatectomy. We examined the effectiveness of the mammalian target of rapamycin (mTOR) inhibitor sirolimus in four infants with severe hyperinsulinemic hypoglycemia that had been unresponsive to maximal doses of diazoxide (20 mg per kilogram of body weight per day) and octreotide (35 μg per kilogram per day). All the patients had a clear glycemic response to sirolimus, although one patient required a small dose of octreotide to maintain normoglycemia. There were no major adverse events during 1 year of follow-up.

Background: Hepatocyte nuclear factor 4 alpha (HNF4A) gene mutations have a well-recognized role in maturity-onset diabetes of the young and have recently been described in congenital hyperinsulinism. A biphasic phenotype has been postulated, with macrosomia and congenital hyperinsulinism in infancy, and diabetes in young adulthood. In this case series, we report three children with HNF4A mutations (two de novo) and diazoxide-responsive congenital hyperinsulinism, highlighting the potential for ongoing diazoxide requirement and the importance of screening for these mutations even in the absence of family history. Case reports: all patients presented with macrosomia (mean birthweight 4.26 kg) and hyperinsulinaemic hypoglycaemia soon after birth (median age 1 day). All three (age range 7 months to 11 years 10 months) remain on diazoxide therapy, with dose requirements increasing in one patient. There was no prior family history of diabetes, neonatal hypoglycaemia or macrosomia. Parents were screened for HNF4A mutations post-diagnosis and one father was subsequently found to have maturity-onset diabetes of the young. Conclusions: This case series follows the evolving course of three patients with confirmed HNF4A-mediated congenital hyperinsulinism, highlighting (1) the variable natural history of these mutations, (2) the potential for prolonged diazoxide requirement, even into adolescence, and (3) the need for screening, regardless of family history. © 2013 Diabetes UK.

Permanent neonatal diabetes mellitus is a rare condition mostly due to heterozygous mutations in the KCNJ11, ABCC8 and INS genes. Neonatal diabetes due to pancreatic agenesis is extremely rare. Mutations in PDX1, PTF1A, HNF1B, EIF2AK3, RFX6 and GATA6 genes have been shown to result in pancreatic agenesis or hypoplasia. This report describes a 40-day-old male infant diagnosed with permanent neonatal diabetes associated with atrial septal defect, pulmonary stenosis, patent ductus arteriosus and a novel de novo heterozygous missense mutation (p.N466S) in the GATA6 gene with no evidence of exocrine pancreas insufficiency. In addition to permanent neonatal diabetes, the patient had transient idiopathic neonatal cholestasis and hypoglycaemic episodes unrelated to insulin treatment, features that are rarely described in children with permanent neonatal diabetes. © 2013 Elsevier Masson SAS.

AIMS: Recessive PDX1 (IPF1) mutations are a rare cause of pancreatic agenesis, with three cases reported worldwide. A recent report described two cousins with a homozygous hypomorphic PDX1 mutation causing permanent neonatal diabetes with subclinical exocrine insufficiency. The aim of our study was to investigate the possibility of hypomorphic PDX1 mutations in a large cohort of patients with permanent neonatal diabetes and no reported pancreatic hypoplasia or exocrine insufficiency. METHODS: PDX1 was sequenced in 103 probands with isolated permanent neonatal diabetes in whom ABCC8, KCNJ11 and INS mutations had been excluded. RESULTS: Sequencing analysis identified biallelic PDX1 mutations in three of the 103 probands with permanent neonatal diabetes (2.9%). One proband and his affected brother were compound heterozygotes for a frameshift and a novel missense mutation (p.A34fsX191; c.98dupC and p.P87L; c.260C>T). The other two probands were homozygous for novel PDX1 missense mutations (p.A152G; c.455C>G and p.R176Q; c.527G>A). Both mutations affect highly conserved residues located within the homeobox domain. None of the four cases showed any evidence of exocrine pancreatic insufficiency, either clinically, or, where data were available, biochemically. In addition a heterozygous nonsense mutation (p.C18X; c.54C>A) was identified in a fourth case. CONCLUSIONS: This study demonstrates that recessive PDX1 mutations are a rare but important cause of isolated permanent neonatal diabetes in patients without pancreatic hypoplasia/agenesis. Inclusion of the PDX1 gene in mutation screening for permanent neonatal diabetes is recommended as a genetic diagnosis reveals the mode of inheritance, allows accurate estimation of recurrence risks and confirms the requirement for insulin treatment.

Background: Congenital hyperinsulinism (CHI) is a clinically heterogeneous condition. Mutations in eight genes (ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A and HNF1A) are known to cause CHI. Aim: to characterise the clinical and molecular aspects of a large cohort of patients with CHI. Methodology: Three hundred patients were recruited and clinical information was collected before genotyping. ABCC8 and KCNJ11 genes were analysed in all patients. Mutations in GLUD1, HADH, GCK and HNF4A genes were sought in patients with diazoxide-responsive CHI with hyperammonaemia (GLUD1), raised 3-hydroxybutyrylcarnitine and/or consanguinity (HADH), positive family history (GCK) or when CHI was diagnosed within the first week of life (HNF4A). Results: Mutations were identified in 136/300 patients (45.3%). Mutations in ABCC8/KCNJ11 were the commonest genetic cause identified (n=109, 36.3%). Among diazoxide-unresponsive patients (n=105), mutations in ABCC8/KCNJ11 were identified in 92 (87.6%) patients, of whom 63 patients had recessively inherited mutations while four patients had dominantly inherited mutations. A paternal mutation in the ABCC8/KCNJ11 genes was identified in 23 diazoxide-unresponsive patients, of whom six had diffuse disease. Among the diazoxide-responsive patients (n=183), mutations were identified in 41 patients (22.4%). These include mutations in ABCC8/KCNJ11 (n=15), HNF4A (n=7), GLUD1 (n=16) and HADH (n=3). Conclusions: a genetic diagnosis was made for 45.3% of patients in this large series. Mutations in the ABCC8 gene were the commonest identifiable cause. The vast majority of patients with diazoxideresponsive CHI (77.6%) had no identifiable mutations, suggesting other genetic and/or environmental mechanisms. © 2013 European Society of Endocrinology.

Congenital hyperinsulinism (CHI) is a common cause of hypoglycemia in infants. We report three cases of CHI with differing clinical, biochemical, and molecular genetic spectra. One patient was unresponsive to medical treatment and died after subtotal pancreatectomy because of complications due to the surgery. Two patients have been followed successfully with medical treatment. Early diagnosis and appropriate treatment of CHI are essential to prevent morbidity and mortality.

Congenital diarrheal disorders consist of a variety of chronic enteropathies. There are approximately 30 different diseases that can be classified into four groups according to the mechanisms involved in pathogenesis: (i) absorption and transport of nutrients and electrolytes; (ii) enterocyte differentiation and polarization; (iii) enteroendocrine cell differentiation; and (iv) modulation of the intestinal immune response. Affected patients often present with life-threatening diarrhea, in the first few weeks of life. A new disorder, enteric anendocrinosis, which is characterized by severe malabsorptive diarrhea and a lack of intestinal enteroendocrine cells has recently been described in six patients with recessively inherited mutations in the Neurogenin-3 gene. In this report we describe a seventh case with a review of the literature. © 2013 Japan Pediatric Society.

We recently reported de novo GATA6 mutations as the most common cause of pancreatic agenesis, accounting for 15 of 27 (56%) patients with insulin-treated neonatal diabetes and exocrine pancreatic insufficiency requiring enzyme replacement therapy. We investigated the role of GATA6 mutations in 171 subjects with neonatal diabetes of unknown genetic etiology from a cohort of 795 patients with neonatal diabetes. Mutations in known genes had been confirmed in 624 patients (including 15 GATA6 mutations). Sequencing of the remaining 171 patients identified nine new case subjects (24 of 795, 3%). Pancreatic agenesis was present in 21 case subjects (six new); two patients had permanent neonatal diabetes with no enzyme supplementation and one had transient neonatal diabetes. Four parents with heterozygous GATA6 mutations were diagnosed with diabetes outside the neonatal period (12-46 years). Subclinical exocrine insufficiency was demonstrated by low fecal elastase in three of four diabetic patients who did not receive enzyme supplementation. One parent with a mosaic mutation was not diabetic but had a heart malformation. Extrapancreatic features were observed in all 24 probands and three parents, with congenital heart defects most frequent (83%). Heterozygous GATA6 mutations cause a wide spectrum of diabetes manifestations, ranging from pancreatic agenesis to adult-onset diabetes with subclinical or no exocrine insufficiency.

Hepatoblastoma is a tumour of early childhood occurring in association with genetic syndromes including Beckwith-Wiedemann Syndrome (BWS) which results from dominance of paternally-inherited genes on chromosome 11p15. We report a child without clinical BWS, neonatally diagnosed with focal congenital hyperinsulinism resulting from a paternally-inherited recessively-acting mutation of ABCC8 and pancreatic paternal uniparental disomy (UPD) for chromosome 11p15, who subsequently developed hepatoblastoma. Genetic testing showed UPD 11p15 in the pancreas and liver but not systemically, allowing the expression of mutated ABCC8 in both tissues. Infants with large or multifocal forms of focal congenital hyperinsulinism may be at risk of BWS-like tumours due to mosaic UPD despite negative whole-blood and buccal DNA testing and tumour surveillance should be considered for this minority. © 2013 Elsevier Masson SAS.

Aims/hypothesis: Current genetic tests for diagnosing monogenic diabetes rely on selection of the appropriate gene for analysis according to the patient's phenotype. Next-generation sequencing enables the simultaneous analysis of multiple genes in a single test. Our aim was to develop a targeted next-generation sequencing assay to detect mutations in all known MODY and neonatal diabetes genes. Methods: We selected 29 genes in which mutations have been reported to cause neonatal diabetes, MODY, maternally inherited diabetes and deafness (MIDD) or familial partial lipodystrophy (FPLD). An exon-capture assay was designed to include coding regions and splice sites. A total of 114 patient samples were tested - 32 with known mutations and 82 previously tested for MODY (n = 33) or neonatal diabetes (n = 49) but in whom a mutation had not been found. Sequence data were analysed for the presence of base substitutions, small insertions or deletions (indels) and exonic deletions or duplications. Results: in the 32 positive controls we detected all previously identified variants (34 mutations and 36 polymorphisms), including 55 base substitutions, ten small insertions or deletions and five partial/whole gene deletions/duplications. Previously unidentified mutations were found in five patients with MODY (15%) and nine with neonatal diabetes (18%). Most of these patients (12/14) had mutations in genes that had not previously been tested. Conclusions/interpretation: Our novel targeted next-generation sequencing assay provides a highly sensitive method for simultaneous analysis of all monogenic diabetes genes. This single test can detect mutations previously identified by Sanger sequencing or multiplex ligation-dependent probe amplification dosage analysis. The increased number of genes tested led to a higher mutation detection rate. © 2013 the Author(s).

AIMS/HYPOTHESIS: Current genetic tests for diagnosing monogenic diabetes rely on selection of the appropriate gene for analysis according to the patient's phenotype. Next-generation sequencing enables the simultaneous analysis of multiple genes in a single test. Our aim was to develop a targeted next-generation sequencing assay to detect mutations in all known MODY and neonatal diabetes genes. METHODS: We selected 29 genes in which mutations have been reported to cause neonatal diabetes, MODY, maternally inherited diabetes and deafness (MIDD) or familial partial lipodystrophy (FPLD). An exon-capture assay was designed to include coding regions and splice sites. A total of 114 patient samples were tested--32 with known mutations and 82 previously tested for MODY (n = 33) or neonatal diabetes (n = 49) but in whom a mutation had not been found. Sequence data were analysed for the presence of base substitutions, small insertions or deletions (indels) and exonic deletions or duplications. RESULTS: in the 32 positive controls we detected all previously identified variants (34 mutations and 36 polymorphisms), including 55 base substitutions, ten small insertions or deletions and five partial/whole gene deletions/duplications. Previously unidentified mutations were found in five patients with MODY (15%) and nine with neonatal diabetes (18%). Most of these patients (12/14) had mutations in genes that had not previously been tested. CONCLUSIONS/INTERPRETATION: Our novel targeted next-generation sequencing assay provides a highly sensitive method for simultaneous analysis of all monogenic diabetes genes. This single test can detect mutations previously identified by Sanger sequencing or multiplex ligation-dependent probe amplification dosage analysis. The increased number of genes tested led to a higher mutation detection rate.

Maturity-onset diabetes of the young (MODY) is a monogenic disorder characterized by autosomal dominant inheritance of young-onset (typically

Maturity-onset diabetes of the young (MODY) is a monogenic disorder characterized by autosomal dominant inheritance of young-onset (typically

Next-generation sequencing (NGS) enables analysis of the human genome on a scale previously unachievable by Sanger sequencing. Exome sequencing of the coding regions and conserved splice sites has been very successful in the identification of disease-causing mutations, and targeting of these regions has extended clinical diagnostic testing from analysis of fewer than ten genes per phenotype to more than 100. Noncoding mutations have been less extensively studied despite evidence from mRNA analysis for the existence of deep intronic mutations in >20 genes. We investigated individuals with hyperinsulinaemic hypoglycaemia and biochemical or genetic evidence to suggest noncoding mutations by using NGS to analyze the entire genomic regions of ABCC8 (117 kb) and HADH (94 kb) from overlapping ∼10 kb PCR amplicons. Two deep intronic mutations, c.1333-1013A>G in ABCC8 and c.636+471G>T HADH, were identified. Both are predicted to create a cryptic splice donor site and an out-of-frame pseudoexon. Sequence analysis of mRNA from affected individuals' fibroblasts or lymphoblastoid cells confirmed mutant transcripts with pseudoexon inclusion and premature termination codons. Testing of additional individuals showed that these are founder mutations in the Irish and Turkish populations, accounting for 14% of focal hyperinsulinism cases and 32% of subjects with HADH mutations in our cohort. The identification of deep intronic mutations has previously focused on the detection of aberrant mRNA transcripts in a subset of disorders for which RNA is readily obtained from the target tissue or ectopically expressed at sufficient levels. Our approach of using NGS to analyze the entire genomic DNA sequence is applicable to any disease. © 2013 the American Society of Human Genetics.

Next-generation sequencing (NGS) enables analysis of the human genome on a scale previously unachievable by Sanger sequencing. Exome sequencing of the coding regions and conserved splice sites has been very successful in the identification of disease-causing mutations, and targeting of these regions has extended clinical diagnostic testing from analysis of fewer than ten genes per phenotype to more than 100. Noncoding mutations have been less extensively studied despite evidence from mRNA analysis for the existence of deep intronic mutations in >20 genes. We investigated individuals with hyperinsulinaemic hypoglycaemia and biochemical or genetic evidence to suggest noncoding mutations by using NGS to analyze the entire genomic regions of ABCC8 (117 kb) and HADH (94 kb) from overlapping ~10 kb PCR amplicons. Two deep intronic mutations, c.1333-1013A>G in ABCC8 and c.636+471G>T HADH, were identified. Both are predicted to create a cryptic splice donor site and an out-of-frame pseudoexon. Sequence analysis of mRNA from affected individuals' fibroblasts or lymphoblastoid cells confirmed mutant transcripts with pseudoexon inclusion and premature termination codons. Testing of additional individuals showed that these are founder mutations in the Irish and Turkish populations, accounting for 14% of focal hyperinsulinism cases and 32% of subjects with HADH mutations in our cohort. The identification of deep intronic mutations has previously focused on the detection of aberrant mRNA transcripts in a subset of disorders for which RNA is readily obtained from the target tissue or ectopically expressed at sufficient levels. Our approach of using NGS to analyze the entire genomic DNA sequence is applicable to any disease.

BACKGROUND: Congenital hyperinsulinism (CHI) is a rare genetic disorder characterised by inappropriate insulin secretion in the face of severe hypoglycaemia. There are two histological subtypes of CHI namely diffuse and focal. Diffuse CHI is most common due to recessive mutations in ABCC8/KCNJ11 (which encode the SUR/KIR6.2 components of the pancreatic β-cell KATP channel) whereas focal CHI is due to a paternally inherited ABCC8/KCNJ11 mutation and somatic loss of heterozygosity for the 11p allele inside the focal lesion. Fluorine-18-l-dihydroxyphenylalanine positron emission tomography/computed tomography ((18)F-DOPA-PET/CT) is used in the pre-operative localisation of focal lesions prior to surgery. Diffuse CHI if medically unresponsive will require a near total pancreatectomy whereas focal CHI will only require a limited lesionectomy, thus curing the patient from the hypoglycaemia. AIMS: to report the first case of genetically confirmed CHI in Singapore from a heterozygous paternally inherited ABCC8 mutation. METHODS/RESULTS: a term male infant presented with severe hyperinsulinaemic hypoglycaemia (HH) after birth and failed medical treatment with diazoxide and octreotide. Genetic testing (paternally inherited mutation in ABCC8/p.D1472N) suggested focal disease, but due to the unavailability of (18)F-DOPA-PET/CT to confirm focal disease, a partial pancreatectomy was performed. Interestingly, histology of the resected pancreatic tissue showed changes typical of diffuse disease. CONCLUSION: Heterozygous paternally inherited ABCC8/KCNJ11 mutations can lead to diffuse or focal CHI. LEARNING POINTS: HH is a cause of severe hypoglycaemia in the newborn period.Paternal mutations in ABCC8/KCNJ11 can lead to diffuse or focal disease.(18)F-DOPA-PET/CT scan is the current imaging of choice for localising focal lesions.Gallium-68 tetra-aza-cyclododecane-N N'N″N-‴-tetra-acetate octreotate PET scan is not a useful imaging tool for localising focal lesions.The molecular mechanism by which a heterozygous ABCC8 mutation leads to diffuse disease is currently unclear.Focal lesions are curable by lesionectomy and so genetic studies in patients with HH must be followed by imaging using (18)F-DOPA-PET/CT scan.

Congenital hyperinsulinism (CHI) is a rare cause of hyperinsulinaemic hypoglycaemia (HH) and is due to an inappropriate secretion of insulin by the pancreatic β-cells. Genetic defects in key genes lead to dysregulated insulin secretion and consequent hypoglycaemia. Mutations in the genes ABCC8/KCNJ11, encoding SUR1/Kir6.2 components of the KATP channels, respectively, are the commonest cause of CHI. A 33+6 week gestation male infant weighing 3.38 kg (above 90th centile) presented with severe neonatal symptomatic hypoglycaemia. He required a glucose infusion rate of 20 mg/kg/min to maintain normoglycaemia (blood glucose levels at >3.5 mmol/l). Investigations established the diagnosis of HH (blood glucose 2.2 mmol/l with simultaneous insulin of 97.4 mU/l). Subsequent molecular genetic studies identified a heterozygous pathogenic ABCC8 missense mutation, p.R1353H (c.4058G>A), inherited from an unaffected mother. His HH was diazoxide responsive and resolved within 3 months of life. Copyright 2013 BMJ Publishing Group. All rights reserved.

Thiamine responsive megaloblastic anemia (TRMA) is an autosomal recessive disease caused by loss of function mutations in the SLC19A2 gene. TRMA is characterized by anemia, deafness, and diabetes. In some cases, optic atrophy or more rarely retinitis pigmentosa is noted. We now report two sisters, the eldest of which presented to a different hospital during childhood with sensorineural deafness, which was treated with a hearing prosthesis, insulin requiring diabetes, retinitis pigmentosa, optic atrophy, and macrocytic anemia. These features initially suggested a clinical diagnosis of Wolfram syndrome (WS). Therapy with thiamine was initiated which resulted in the resolution of the anemia. The younger sister, who was affected with sensorineural deafness, was referred to our hospital for non-autoimmune diabetes. She was found to have macrocytosis and ocular abnormalities. Because a diagnosis of TRMA was suspected, therapy with insulin and thiamine was started. Sequencing analysis of the SLC19A2 gene identified a compound heterozygous mutation p.Y81X/p.L457X (c.242insA/c.1370delT) in both sisters. Non-autoimmune diabetes associated with deafness and macrocytosis, without anemia, suggests a diagnosis of TRMA. Patients clinically diagnosed with WS with anemia and/or macrocytosis should be reevaluated for TRMA. © 2012 John Wiley & Sons A/S.

Neonatal diabetes mellitus (NDM) is a rare form of diabetes that presents within the first six months of life. Nearly 70% of these cases have loss of methylation at the differentially methylated region on chromosome 6q24. To describe the findings in a Turkish male patient with NDM caused by a loss of methylation at chromosome 6q24 and three novel homozygous mutations in the ZFP57 gene, methylation-specific PCR was carried out at 6q24 and mutation analysis of ZFP57 gene was maintained by direct sequencing. Sequencing of ZFP57 gene revealed the hypomethylation of chromosome 6q24 and three novel mutations (chr6:29.641.413 A>T, 29.641.073 C>T, and 29.640.855 G>C), respectively. The latter mutation seems to display the patient's condition due to a highly conservative amino acid substitution in the protein. We suggest the ZFP57 gene as a causative factor for NDM and it should be considered in genetic testing. Further studies including functional analysis of the detected mutations will provide precise information regarding the effect of the mutations. Key words: ZFP57 gene, transient neonatal diabetes mellitus, Turkish, novel mutations © Journal of Clinical Research in Pediatric Endocrinology, Published by Galenos Publishing.

BACKGROUND: Mutations in the KCNJ11 gene, which encodes the Kir6.2 subunit of the β-cell K(ATP) channel, are a common cause of neonatal diabetes. The diabetes may be permanent neonatal diabetes mellitus (PNDM) or transient neonatal diabetes mellitus (TNDM), and in ≈ 20% of patients, neurological features are observed. A correlation between the position of the mutation in the protein and the clinical phenotype has previously been described; however, recently, this association has become less distinct with different mutations at the same residues now reported in patients with different diabetic and/or neurological phenotypes. METHODS: We identified from the literature, and our unpublished series, KCNJ11 mutations that affected residues harbouring various amino acid substitutions (AAS) causing differences in diabetic or neurological status. Using the Grantham amino acid scoring system, we investigated whether the difference in properties between the wild-type and the different AAS at the same residue could predict phenotypic severity. RESULTS: Pair-wise analysis demonstrated higher Grantham scores for mutations causing PNDM or diabetes with neurological features when compared with mutations affecting the same residue that causes TNDM (P=0.013) or diabetes without neurological features (P=0.016) respectively. In just five of the 25 pair-wise analyses, a lower Grantham score was observed for the more severe phenotype. In each case, the wild-type residue was glycine, the simplest amino acid. CONCLUSION: This study demonstrates the importance of the specific AAS in determining phenotype and highlights the potential utility of the Grantham score for predicting phenotypic severity for novel KCNJ11 mutations affecting previously mutated residues.

We report a series of patients with transient neonatal diabetes mellitus (TNDM). Paternal uniparental isodisomy of chromosome 6 and heterozygous KCNJ11 and ABC88 mutation were the mutations found. This first reported series of Brazilian patients expands the geographical data on TNDM contributing to better understanding of its pathophysiology. © 2012.

BACKGROUND: Galactokinase catalyses the first committed step in galactose metabolism, the conversion of galactose to galactose-1-phosphate. Galactokinase deficiency is an extremely rare form of galactosaemia, and the most frequent complication reported is cataracts. Congenital hyperinsulinism (CHI) is a cause of severe hypoglycaemia in the newborn period. Galactosaemia has not previously been reported in a neonate with concomitant CHI. AIMS: to report the first case of a patient with CHI and galactokinase deficiency, and to describe the diagnostic pitfalls with bedside blood glucose testing in a neonate with combined galactokinase deficiency and CHI. PATIENTS/METHODS: a 3-day-old baby girl from consanguineous parents presented with poor feeding, irritability and seizures. Capillary blood glucose testing using bedside test strips and glucometer showed a glucose level of 18 mmol/L, but the actual laboratory blood glucose level was only 1.8 mmol/L. After discontinuation of oral feeding (stopping provision of dietary galactose), the bedside capillary blood glucose correlated with laboratory glucose concentrations. RESULTS: Biochemically the patient had CHI (blood glucose level 2.3 mmol/L with simultaneous serum insulin level of 30 mU/L) and galactokinase deficiency (elevated serum galactose level 0.62 μmol/L). Homozygous loss of function mutations in ABCC8 and GALK1 were found, which explained the patient's CHI and galactokinase deficiency, respectively. CONCLUSION: This is the first reported case of CHI and galactokinase deficiency occurring in the same patient. Severe hypoglycaemia in neonates with CHI may go undetected with bedside blood glucose meters in patients with galactokinase deficiency.

AIMS/HYPOTHESIS: the ABCC8 gene encodes the sulfonylurea receptor 1 (SUR1) subunit of the pancreatic beta cell ATP-sensitive potassium (K(ATP)) channel. Inactivating mutations cause congenital hyperinsulinism (CHI) and activating mutations cause transient neonatal diabetes (TNDM) or permanent neonatal diabetes (PNDM) that can usually be treated with sulfonylureas. Sulfonylurea sensitivity is also a feature of HNF1A and HNF4A MODY, but patients referred for genetic testing with clinical features of these types of diabetes do not always have mutations in the HNF1A/4A genes. Our aim was to establish whether mutations in the ABCC8 gene cause MODY that is responsive to sulfonylurea therapy. METHODS: We sequenced the ABCC8 gene in 85 patients with a BMI

Background/Objective: Mutations in the KATP channel genes are the commonest cause of permanent neonatal diabetes. Most patients obtain optimal glycemic control on sulfonylurea treatment. Genetic testing is currently recommended for all infants diagnosed before 6 months of age. We aimed to explore the prevalence of KATP channel diabetes in infants presenting between 6 and 12 months. Methods: the KCNJ11 and ABCC8 genes were sequenced in 115 infants with permanent diabetes diagnosed between 6 and 12 months and in 405 patients presenting before 6 months. Results: Mutations in either gene were identified in 197 patients diagnosed before 6 months (48.6%), three infants diagnosed between 6 and 9 months (4.2%) and none of those diagnosed after 9 months. Two patients diagnosed after 6 months were successfully transferred from insulin to sulfonylureas. Conclusion: KATP channel mutations are an uncommon cause of diabetes in infants presenting after 6 months. However, given the potential clinical benefit from identifying a KATP channel mutation, we recommend that KATP mutation testing should be routinely extended to infants diagnosed up to 9 months. © 2011 John Wiley & Sons A/S.

BACKGROUND/OBJECTIVE: Mutations in the K(ATP) channel genes are the commonest cause of permanent neonatal diabetes. Most patients obtain optimal glycemic control on sulfonylurea treatment. Genetic testing is currently recommended for all infants diagnosed before 6 months of age. We aimed to explore the prevalence of K(ATP) channel diabetes in infants presenting between 6 and 12 months. METHODS: the KCNJ11 and ABCC8 genes were sequenced in 115 infants with permanent diabetes diagnosed between 6 and 12 months and in 405 patients presenting before 6 months. RESULTS: Mutations in either gene were identified in 197 patients diagnosed before 6 months (48.6%), three infants diagnosed between 6 and 9 months (4.2%) and none of those diagnosed after 9 months. Two patients diagnosed after 6 months were successfully transferred from insulin to sulfonylureas. CONCLUSION: K(ATP) channel mutations are an uncommon cause of diabetes in infants presenting after 6 months. However, given the potential clinical benefit from identifying a K(ATP) channel mutation, we recommend that K(ATP) mutation testing should be routinely extended to infants diagnosed up to 9 months.

Background: Loss of function mutations in 3-Hydroxyacyl-CoA Dehydrogenase (HADH) cause protein sensitive hyperinsulinaemic hypoglycaemia (HH). HADH encodes short chain 3-hydroxacyl-CoA dehydrogenase, an enzyme that catalyses the penultimate reaction in mitochondrial β-oxidation of fatty acids. Mutations in GLUD1 encoding glutamate dehydrogenase, also cause protein sensitive HH (due to leucine sensitivity). Reports suggest a protein-protein interaction between HADH and GDH. This study was undertaken in order to understand the mechanism of protein sensitivity in patients with HADH mutations. Methods: an oral leucine tolerance test was conducted in controls and nine patients with HADH mutations. Basal GDH activity and the effect of GTP were determined in lymphoblast homogenates from 4 patients and 3 controls. Immunoprecipitation was conducted in patient and control lymphoblasts to investigate protein interactions. Results: Patients demonstrated severe HH (glucose range 1.73.2 mmol/l; insulin range 4.8-63.8 mU/l) in response to the oral leucine load, this HH was not observed in control patients subjected to the same leucine load. Basal GDH activity and half maximal inhibitory concentration of GTP was similar in patients and controls. HADH protein could be co-immunoprecipitated with GDH protein in control samples but not in patient samples. Conclusions: We conclude that GDH and HADH have a direct protein-protein interaction, which is lost in patients with HADH mutations causing leucine induced HH. This is not associated with loss of inhibitory effect of GTP on GDH (as in patients with GLUD1 mutations). © 2012 Heslegrave et al.; licensee BioMed Central Ltd.

Inactivating mutations in the pancreatic beta cell ATP-sensitive potassium (K(ATP) ) channel genes are identified by sequencing in approximately 80% of patients with diazoxide-unresponsive hyperinsulinaemic hypoglycaemia (HH). Genetic testing is clinically important as the mode of inheritance of a K(ATP) channel mutation(s) provides information on the histological subtype. For example in patients with a single paternally inherited mutation a focal lesion is possible and once confirmed, the patient can undergo a curative lesionectomy. By contrast, recessive inheritance indicates diffuse disease, which requires near-total pancreatectomy, if medical management is unsuccessful. We investigated ABCC8 and KCNJ11 gene dosage in 29 probands from a cohort of 125 with diazoxide-unresponsive HH where sequencing did not provide a genetic diagnosis. We identified heterozygous partial ABCC8 deletions in four probands. In two cases with focal pancreatic disease, a paternally inherited deletion was found. Two other probands with diffuse pancreatic disease were compound heterozygotes for a deletion and a recessively acting mutation that had been identified by sequencing. Family member studies confirmed compound heterozygosity for the deletion and the missense mutation in two affected siblings of one proband. Heterozygous deletions of the ABCC8 gene are a rare, but important cause of diazoxide-unresponsive HH. Dosage analysis should be undertaken in all patients when sequencing analysis does not confirm the genetic diagnosis as confirmation of the mode of inheritance can guide clinical management and will provide important information regarding recurrence risk.

Most cases of permanent form of neonatal diabetes mellitus (PNDM) are due to dominant heterozygous gain of function (activating) mutations in either KCNJ11 or ABCC8 genes, that code for Kir 6.2 and SUR1 subunits, respectively of the pancreatic b cell KATP channel. We describe the interesting case of an infant with PNDM, in whom a compound heterozygous activating/ inactivating mutation was found with clinically unaffected parents, each carrying a heterozygous mutation in ABCC8, one predicting gain of function (neonatal diabetes) and the other a loss of function (hyperinsulinemia).

Objective: Mutations in the KCNJ11 and ABCC8 genes that encode the pancreatic K ATP channel are the commonest cause of permanent neonatal diabetes mellitus (PNDM). The authors aimed to define the genetic causes of PNDM in a large cohort of Arab patients and compare them with a British cohort tested in the same laboratory. Design: Retrospective observational study. Setting: International genetics centre. Patients: Arab and British subjects with PNDM who were referred for genetic testing over the same period. Intervention: Comparison of genotypes and phenotypes between the two cohorts. Main outcome measures: the aetiology and phenotype of PNDM in an Arab compared to a British cohort. Results: 88 Arab and 77 British probands were referred between 2006 and 2011, inclusive. Consanguinity was higher among Arabs (63.6% vs 10.4%) and a higher percentage had a genetic diagnosis compared to the British cohort (63.6% vs 41.6%). Recessive EIF2AK3 gene mutations were the commonest cause of PNDM in the Arab cohort (22.7%) followed by INS (12.5%), and KCNJ11 and GCK (5.7% each), whereas K ATP channel mutations were the commonest cause (29.9%) in the British cohort. In 37.5% of Arab patients PNDM was part of a genetic syndrome compared to 7.8% of the British cohort. Conclusion: PNDM in the Arab population has a different genetic spectrum compared to British patients where KATP channel mutations are the commonest cause, similar to other European populations. In Arabs, PNDM is more likely to be part of a recessively inherited syndrome, possibly due to the higher rate of consanguinity.

Permanent neonatal diabetes mellitus (PNDM) is diagnosed within the first 6 months of life, and is usually monogenic in origin. Heterozygous mutations in ABCC8, KCNJ11, and INS genes account for around half of cases of PNDM; mutations in 10 further genes account for a further 10%, and the remaining 40% of cases are currently without a molecular genetic diagnosis. Thiamine-responsive megaloblastic anaemia (TRMA), due to mutations in the thiamine transporter SLC19A2, is associated with the classical clinical triad of diabetes, deafness, and megaloblastic anaemia. Diabetes in this condition is well described in infancy but has only very rarely been reported in association with neonatal diabetes. We used a combination of homozygosity mapping and evaluation of clinical information to identify cases of TRMA from our cohort of patients with PNDM. Homozygous mutations in SLC19A2 were identified in three cases in which diabetes presented in the first 6 months of life, and a further two cases in which diabetes presented between 6 and 12 months of age. We noted the presence of a significant neurological disorder in four of the five cases in our series, prompting us to examine the incidence of these and other non-classical clinical features in TRMA. From 30 cases reported in the literature, we found significant neurological deficit (stroke, focal, or generalized epilepsy) in 27%, visual system disturbance in 43%, and cardiac abnormalities in 27% of cases. TRMA should be considered in the differential diagnosis of diabetes presenting in the neonatal period. © 2012 John Wiley & Sons A/S.

Aims: the gene SLC2A2 encodes GLUT2, which is found predominantly in pancreas, liver, kidney and intestine. In mice, GLUT2 is the major glucose transporter into pancreatic beta cells, and biallelic Slc2a2 inactivation causes lethal neonatal diabetes. The role of GLUT2 in human beta cells is controversial, and biallelic SLC2A2 mutations cause Fanconi-Bickel syndrome (FBS), with diabetes rarely reported. We investigated the potential role of GLUT2 in the neonatal period by testing whether SLC2A2 mutations can present with neonatal diabetes before the clinical features of FBS appear. Methods: We studied SLC2A2 in patients with transient neonatal diabetes mellitus (TNDM; n = 25) or permanent neonatal diabetes mellitus (PNDM; n = 79) in whom we had excluded the common genetic causes of neonatal diabetes, using a combined approach of sequencing and homozygosity mapping. Results: of 104 patients, five (5%) were found to have homozygous SLC2A2 mutations, including four novel mutations (S203R, M376R, c.963+1G>A, F114LfsX16). Four out of five patients with SLC2A2 mutations presented with isolated diabetes and later developed features of FBS. Four out of five patients had TNDM (16% of our TNDM cohort of unknown aetiology). One patient with PNDM remains on insulin at 28 months. Conclusions: SLC2A2 mutations are an autosomal recessive cause of neonatal diabetes that should be considered in consanguineous families or those with TNDM, after excluding common causes, even in the absence of features of FBS. The finding that patients with homozygous SLC2A2 mutations can have neonatal diabetes supports a role for GLUT2 in the human beta cell. © 2012 Springer-Verlag.

AIMS: the gene SLC2A2 encodes GLUT2, which is found predominantly in pancreas, liver, kidney and intestine. In mice, GLUT2 is the major glucose transporter into pancreatic beta cells, and biallelic Slc2a2 inactivation causes lethal neonatal diabetes. The role of GLUT2 in human beta cells is controversial, and biallelic SLC2A2 mutations cause Fanconi-Bickel syndrome (FBS), with diabetes rarely reported. We investigated the potential role of GLUT2 in the neonatal period by testing whether SLC2A2 mutations can present with neonatal diabetes before the clinical features of FBS appear. METHODS: We studied SLC2A2 in patients with transient neonatal diabetes mellitus (TNDM; n = 25) or permanent neonatal diabetes mellitus (PNDM; n = 79) in whom we had excluded the common genetic causes of neonatal diabetes, using a combined approach of sequencing and homozygosity mapping. RESULTS: of 104 patients, five (5%) were found to have homozygous SLC2A2 mutations, including four novel mutations (S203R, M376R, c.963+1G>A, F114LfsX16). Four out of five patients with SLC2A2 mutations presented with isolated diabetes and later developed features of FBS. Four out of five patients had TNDM (16% of our TNDM cohort of unknown aetiology). One patient with PNDM remains on insulin at 28 months. CONCLUSIONS: SLC2A2 mutations are an autosomal recessive cause of neonatal diabetes that should be considered in consanguineous families or those with TNDM, after excluding common causes, even in the absence of features of FBS. The finding that patients with homozygous SLC2A2 mutations can have neonatal diabetes supports a role for GLUT2 in the human beta cell.

Neonatal/infancy-onset diabetes mellitus is a monogenic form of diabetes with onset within 6 months of age. Two distinct types of neonatal diabetes mellitus have been recognized: permanent and transient. Mutations within the K ATP channel and insulin genes are found in most patients with permanent diabetes mellitus. There have been several reports of the successful transition from insulin to sulfonylurea agents in patients with permanent diabetes mellitus caused by mutations in the KCNJ11 gene. We report on a term female neonate with a novel missense mutation, p.P1199L, in the ABCC8 gene that encodes the sulfonylurea receptor 1 whose treatment was successfully converted from insulin to sulfonylurea. © 2012 Nature America, Inc. All rights reserved.

Objective: Ventricular hypertrophy (VH) has been observed in children with congenital hyperinsulinism (CHI), a condition of hypoglycaemia characterised by dysregulated insulin secretion, but the prevalence is not known. Patients and methods: Cardiac assessment was performed in children (n=49) with CHI at diagnosis and follow-up. Two dimensional and Doppler echocardiography studies were used to assess cardiac structures, while M-mode study was used to measure left ventricular (LV) dimensions, subsequently converted to Z scores. Where possible, LV hypertrophy was confirmed by LV mass index (g/m2.7) >95th centile. Results: Cardiac structural lesions were found in 14 (28%) children. At initial echocardiography, VH was present in 31 (65%) children with median (range) LV posterior wall dimension in diastole Z scores of +1.6 (-2.4 to +5.8) and interventricular septal wall dimension in end diastole Z scores of +1.9 (-1.7 to +17.2). At follow-up echocardiography, performed after an interval of 178 (45-390) days, VH persisted in 16 (33%) children. In regression analysis, the presence of VH (odds ratio (95% confidence intervals) 1.1 (1.0-1.2), P = 0.04) at initial echocardiography was correlated with maximum glucose requirement at diagnosis, indicating that severity of CHI at presentation may play a role in the pathogenesis of VH. Conclusions: a significant proportion of children with CHI have cardiac structural lesions. A majority also have VH, which may be associated with the severity of CHI at diagnosis. VH may persist in some children, which requires careful long-term cardiac review. © 2012 European Society of Endocrinology.

BACKGROUND: Congenital hyperinsulinism (CHI) is a cause of persistent hypoglycemia due to unregulated insulin secretion from pancreatic β-cells. Histologically, there are two major subgroups, focal and diffuse. Focal CHI is typically unresponsive to diazoxide and can be cured with surgical removal of the focal lesion. AIMS: We report on three patients with focal CHI to illustrate the marked clinical, genetic, radiological, and histological heterogeneity. METHODS AND RESULTS: the first two patients had focal CHI due to a paternal (c.3992-9G→A) ABCC8 mutation. One of these patients was fully responsive to a small dose (5 mg/kg · d) of diazoxide, whereas the other patient was medically unresponsive. In both patients, the focal lesions were accurately localized preoperatively by [(18)F]dihydroxyphenylalanine (DOPA) positron emission tomography (PET) and surgically resected. The third patient had a paternally inherited ABCC8 (A1493T) mutation, and the initial [(18)F]DOPA PET scan indicated extensive uptake of DOPA in the body and tail of the pancreas. However, despite surgical resection of the body and tail, this patient continued to have severe CHI. A subsequent [(18)F]DOPA PET scan now showed markedly increased DOPA uptake in the remaining body and head of the pancreas. This focal lesion occupied virtually the whole of the pancreas. conclusions: These three cases illustrate that focal lesions even with the same genotype (c.3992-9G→A) may have a different clinical presentation and that [(18)F]DOPA PET scans in very large focal lesions may be difficult to interpret.

Homozygous mutations in the glucokinase gene (GCK) result in a complete deficiency of the GCK enzyme, which leads to permanent neonatal diabetes mellitus. Whilst there has been one report of a patient (with a homozygous p.T168A) who was diagnosed with diabetes at the age of 2 months, all other cases were diagnosed with diabetes within the first 2 weeks of life. We now report a second unrelated patient with the same p.T168A GCK mutation who was diagnosed with diabetes at the age of 9 months. We conclude that the specific GCK mutation, as yet unidentified genetic modifiers, and/or environmental factors might have different effects on pancreatic β-cell functions, causing variability in the age at diagnosis of diabetes.

OBJECTIVE: Congenital hyperinsulinism (CHI) is characterized by persistent hypoglycemia due to the inappropriate insulin secretion. Inactivating mutations in the ABCC8 and KCNJ11 genes, which encode the sulfonylurea receptor 1 and Kir6.2 subunits of the ATP-sensitive K(+) (K(ATP)) channel in pancreatic β-cell, are the most common cause of CHI. We studied the genetic etiology and phenotypes of CHI in Korean patients. METHODS: ABCC8 and KCNJ11 mutational analysis was performed in 17 patients with CHI. Medical records were retrospectively reviewed to identify phenotypes. RESULTS: Mutations (12 ABCC8 and three KCNJ11) were identified in 82% (14/17) of patients. of these, nine ABCC8 mutations (E100X, W430X, c.1630+1G>C, D813N, Q923X, E1087_A1094delinsDKSDT, Q1134H, H1135W, and E1209Rfs) and one KCNJ11 mutation (W91X) were novel. of the 14 patients, four had confirming recessively inherited CHI. The remaining ten patients had single heterozygous mutations. The majority (12/17) of patients were medically responsive. of the five diazoxide-responsive patients, four had an ABCC8 mutation. The five patients unresponsive to medical management and one diazoxide-responsive patient underwent pancreatectomy and had diffuse histology. of the operated six patients, two had recessively inherited mutations; three patients had a single heterozygous mutation (one maternally and two paternally inherited); and one patient had no identifiable K(ATP) channel mutation. CONCLUSIONS: This is the first study to report genotype and phenotype correlations among Korean patients with CHI. Mutations in ABCC8 and KCNJ11 are the most common causes of CHI in Korean patients. Similar to other studies, there is marked genetic heterogeneity and no clear genotype-phenotype correlation.

Congenital hyperinsulinism is the most frequent cause of severe, persistent hypoglycemia in infancy and childhood. We report a 2.5 year old girl with severe congenital hyperinsulinism. Mutation analysis showed that the child is a compound heterozygote for two missense mutations in the ABCC8 gene.

Recessive inactivating mutations in the ABCC8 and KCNJ11 genes encoding the adenosine triphosphate-sensitive potassium (K(ATP)) channel subunit sulphonylurea receptor 1 (SUR1) and inwardly rectifying potassium channel subunit (Kir6.2) are the most common cause of hyperinsulinaemic hypoglycaemia (HH). Most of these patients do not respond to treatment with the (K(ATP)) channel agonist diazoxide. Dominant inactivating ABCC8 and KCNJ11 mutations are less frequent, but are usually associated with a milder form of hypoglycaemia that is responsive to diazoxide therapy. We studied five patients from four families with HH who were unresponsive to diazoxide and required a near total pancreatectomy. Mutations in KCNJ11 and ABCC8 were sought by sequencing and dosage analysis. Three novel heterozygous ABCC8 mis-sense mutations (G1485E, D1506E and M1514K) were identified in four probands. All the mutations affect residues located within the Nucleotide Binding Domain 2 of the SUR1 subunit. Testing of family members showed that the mutations had arisen de novo with dominant inheritance in one pedigree. This study extends the clinical phenotype associated with dominant (K(ATP)) channel mutations to include severe congenital HH requiring near total pancreatectomy in addition to a milder form of diazoxide responsive hypoglycaemia. The identification of dominant vs recessive mutations does not predict clinical course but it is important for estimating the risk of HH in future siblings and offspring.

BACKGROUND: Congenital hyperinsulinism (CHI) is a cause of persistent hypoglycemia. Histologically, there are two subgroups, diffuse and focal. Focal CHI is a consequence of two independent events, inheritance of a paternal mutation in ABCC8/KCNJ11 and paternal uniparental isodisomy of chromosome 11p15 within the embryonic pancreas, leading to an imbalance in the expression of imprinted genes. The probability of both events occurring within siblings is rare. AIM: We describe the first familial form of focal CHI in two siblings. PATIENTS AND METHODS: the proband presented with medically unresponsive CHI. He underwent pancreatic venous sampling and Fluorine-18-L-dihydroxyphenylalanine positron emission tomography scan, which localized a 5-mm focal lesion in the isthmus of the pancreas. The sibling presented 8 yr later also with medically unresponsive CHI. An Fluorine-18-L-dihydroxyphenylalanine positron emission-computerised tomography scan showed a 7-mm focal lesion in the posterior section of the head of the pancreas. Both siblings were found to be heterozygous for two paternally inherited ABCC8 mutations, A355T and R1494W. Surgical removal of the focal lesions in both siblings cured the Hyperinsulinaemic hypoglycaemia. CONCLUSION: This is the first report of focal CHI occurring in siblings. Genetic counseling for families of patients with focal CHI should be recommended, despite the rare risk of recurrence of this disease.

Understanding the regulation of pancreatic development is key for efforts to develop new regenerative therapeutic approaches for diabetes. Rare mutations in PDX1 and PTF1A can cause pancreatic agenesis, however, most instances of this disorder are of unknown origin. We report de novo heterozygous inactivating mutations in GATA6 in 15/27 (56%) individuals with pancreatic agenesis. These findings define the most common cause of human pancreatic agenesis and establish a key role for the transcription factor GATA6 in human pancreatic development.

A genetic diagnosis is now possible for approximately 45%-55% of patients with hyperinsulinemic hypoglycemia. Understanding the genetic etiology of the disease in these patients is clinically important because a genetic diagnosis will provide information on prognosis, recurrence risk, and importantly may also guide clinical management. The aim of this review is to provide an outline of the 7 different molecular mechanisms underlying this heterogeneous disease and to demonstrate that the clinical phenotype can act as a useful guide when prioritizing the order of genetic testing.

CONTEXT AND OBJECTIVE: Recessive mutations in the hydroxyacyl-CoA dehydrogenase (HADH) gene encoding the enzyme 3-hydroxyacyl-CoA dehydrogenase are a rare cause of diazoxide-responsive hyperinsulinemic hypoglycemia (HH) with just five probands reported to date. HADH deficiency in the first three identified patients was associated with detectable urinary 3-hydroxyglutarate and raised plasma 3-hydroxybutyryl-carnitine levels, but two recent cases did not have abnormal urine organic acids or acylcarnitines. RESEARCH DESIGN AND METHODS: We studied 115 patients with diazoxide-responsive HH in whom the common genetic causes of HH had been excluded. No patients were reported to have abnormal acylcarnitines or urinary organic acids. Homozygosity mapping was undertaken in probands from 13 consanguineous pedigrees to search for regions harboring mutations that are identical by descent. RESULTS: HADH sequencing was performed after genome-wide single nucleotide polymorphism analysis revealed a large shared region of homozygosity spanning the HADH locus in six unrelated probands. Homozygous mutations were identified in three of these patients and in a further two probands from consanguineous families. HADH analysis in the remainder of the cohort identified mutations in a further six probands for whom consanguinity was not reported, but who originated from countries with high rates of consanguinity. Six different HADH mutations were identified in 11/115 (10%) patients tested. CONCLUSION: HADH mutations are a relatively common cause of diazoxide-responsive HH with a frequency similar to that of GLUD1 and HNF4A mutations. We recommend that HADH sequence analysis is considered in all patients with diazoxide-responsive HH when recessive inheritance is suspected.

Aims/hypothesis: Dominantly acting loss-of-function mutations in the ABCC8/KCNJ11 genes can cause mild medically responsive hyperinsulinaemic hypoglycaemia (HH). As controversy exists over whether these mutations predispose to diabetes in adulthood we investigated the prevalence of diabetes in families with dominantly inherited ATP-sensitive potassium (KATP) channel mutations causing HH in the proband. Methods: We studied the phenotype of 30 mutation carriers (14 children and 16 adults) from nine families with dominant ABCC8/KCNJ11 mutations. Functional consequences of six novel missense mutations were examined by reconstituting the KATP channel in human embryonic kidney 293 (HEK293) cells and evaluating the effect of drugs and metabolic poisoning on the channels using the 86Rb flux assay. Results: the mutant channels all showed a lack of 86Rb efflux on exposure to the channel agonist diazoxide or metabolic inhibition. In the families, dominant ABCC8/KCNJ11 mutations were associated with increased birthweight (median + 1.56 SD score [SDS]). Fourteen children had HH and five adults were reported with HH or hypoglycaemic episodes (63%). Progression from hypoglycaemia to diabetes mellitus occurred in two individuals. Eight adults had a history of gestational diabetes in multiple pregnancies or were diabetic (diagnosed at a median age of 31 years). Within these families, none of the 19 adults who were not carriers of the ABCC8/KCNJ11 mutation was known to be diabetic. Conclusions/interpretation: the phenotype associated with dominant ABCC8/KCNJ11 mutations ranges from asymptomatic macrosomia to persistent HH in childhood. In adults, it may also be an important cause of dominantly inherited early-onset diabetes mellitus. © 2011 the Author(s).

OBJECTIVE - Congenital hyperinsulinism in infancy (CHI) is characterized by unregulated insulin secretion from pancreatic β-cells; severe forms are associated with defects in ABCC8 and KCNJ11 genes encoding sulfonylurea receptor 1 (SUR1) and Kir6.2 subunits, which form ATP-sensitive K+ (K ATP) channels in β-cells. Diazoxide therapy often fails in the treatment of CHI and may be a result of reduced cell surface expression of KATP channels. We hypothesized that conditions known to facilitate trafficking of cystic fibrosis transmembrane regulator (CFTR) and other proteins in recombinant expression systems might increase surface expression of K ATP channels in native CHI β-cells. RESEARCH DESIGN AND METHODS - Tissue was isolated during pancreatectomy from eight patients with CHI and from adult cadaver organ donors. Patients were screened for mutations in ABCC8 and KCNJ11. Isolated β-cells were maintained at 37°C or 25°C and in the presence of 1) phorbol myristic acid, forskolin and 3-isobutyl-1- methylxanthine, 2) BPDZ 154, or 3) 4-phenylbutyrate. Surface expression of functional channels was assessed by patch-clamp electrophysiology. RESULTS - Mutations in ABCC8 were detected for all patients tested (n = 7/8) and included three novel mutations. In five of eight patients, no changes in KATP channel activity were observed under different cell culture conditions. However, in three patients, in vitro recovery of functional KATP channels occurred. Here, we report the first cases of recovery of defective K ATP channels in human β-cells using modified cell culture conditions. CONCLUSIONS - Our study establishes the principle that chemical modification of KATP channel subunit trafficking could be of benefit for the future treatment of CHI. © 2011 by the American Diabetes Association.

Advances in high-throughput sequencing techniques had presented a significant challenge to the processing capabilities of genetic laboratories. However, recent developments in the field of semi-automated mutation detection have revolutionised the task of mutation detection.This chapter provides user information for one commercially available program, Mutation Surveyor. The software is manufactured by SoftGenetics (Pennsylvania, USA) and provides an accurate and efficient program for detecting sequence variants. The chapter focuses on the methodology of setting up GenBank files as reference files and provides information on analysis parameters and data processing.

OBJECTIVE - Two novel mutations (E1506D, E1506G) in the nucleotide-binding domain 2 (NBD2) of the ATP-sensitive K+ channel (KATP channel) sulfonylurea receptor 1 (SUR1) subunit were detected heterozygously in patients with neonatal diabetes. A mutation at the same residue (E1506K) was previously shown to cause congenital hyperinsulinemia. We sought to understand why mutations at the same residue can cause either neonatal diabetes or hyperinsulinemia. RESEARCH DESIGN AND METHODS - Neonatal diabetic patients were sequenced for mutations in ABCC8 (SUR1) and KCNJ11 (Kir6.2). Wild-type and mutant KATP channels were expressed in Xenopus laevis oocytes and studied with electrophysiological methods. RESULTS - Oocytes expressing neonatal diabetes mutant channels had larger resting whole-cell KATP currents than wild-type, consistent with the patients' diabetes. Conversely, no E1506K currents were recorded at rest or after metabolic inhibition, as expected for a mutation causing hyperinsulinemia. KATP channels are activated by Mg-nucleotides (via SUR1) and blocked by ATP (via Kir6.2). All mutations decreased channel activation by MgADP but had little effect on MgATP activation, as assessed using an ATP-insensitive Kir6.2 subunit. Importantly, using wild-type Kir6.2, a 30-s preconditioning exposure to physiological MgATP concentrations (>300 μmol/L) caused a marked reduction in the ATP sensitivity of neonatal diabetic channels, a small decrease in that of wild-type channels, and no change for E1506K channels. This difference in MgATP inhibition may explain the difference in resting whole-cell currents found for the neonatal diabetes and hyperinsulinemia mutations. CONCLUSIONS - Mutations in the same residue can cause either hyperinsulinemia or neonatal diabetes. Differentially altered nucleotide regulation by NBD2 of SUR1 can explain the respective clinical phenotypes. © 2011 by the American Diabetes Association.

BACKGROUND: Loss of function mutations in the genes encoding the pancreatic β-cell ATP-sensitive potassium (KATP) channel are identified in approximately 80% of patients with diazoxide unresponsive hyperinsulinemic hypoglycemia (HH). For a small number of patients HH can occur as part of a multisystem disease such as Beckwith-Wiedemann syndrome (BWS). In approximately 20% of patients, BWS results from chromosome 11 paternal uniparental disomy (UPD), which causes dysregulation of imprinted growth regulation genes at 11p15.5. There is a considerable range in the clinical features and phenotypic severity associated with BWS which is likely to be due to somatic mosaicism. The cause of HH in these patients is not known. RESEARCH DESIGN AND METHODS: We undertook microsatellite analysis of 12 markers spanning chromosome 11p in two patients with severe HH and diffuse disease requiring a pancreatectomy. In both patients mutations in the K(ATP) channel genes had not been identified. RESULTS: We identified segmental paternal UPD in DNA extracted from pancreatic tissue in both patients. UPD was not observed in DNA extracted from the patient's leukocytes or buccal samples. In both cases the UPD encompassed the differentially methylated region at chromosome 11p15.5. Despite this neither patient had any further features of BWS. CONCLUSION: Paternal UPD of the chromosome 11p15.5 differentially methylated region limited to the pancreatic tissue may represent a novel cause of isolated diazoxide unresponsive HH. Loss of heterozygosity studies should therefore be considered in all patients with severe HH who have undergone pancreatic surgery when K(ATP) channel mutation(s) have not been identified.

OBJECTIVE: in children with congenital hyperinsulinism (CHI), K(ATP) channel genes (ABCC8 and KCNJ11) can be screened rapidly for potential pathogenic mutations. We aimed to assess the contribution of rapid genetic testing to the clinical management of CHI. DESIGN: Follow-up observational study at two CHI referral hospitals. METHODS: Clinical outcomes such as subtotal pancreatectomy, (18)F-Dopa positron emission tomography-computed tomography (PET-CT) scanning, stability on medical treatment and remission were assessed in a cohort of 101 children with CHI. RESULTS: in total, 32 (32%) children had pathogenic mutations in K(ATP) channel genes (27 in ABCC8 and five in KCNJ11), of which 11 (34%) were novel. In those negative at initial screening, other mutations (GLUD1, GCK, and HNF4A) were identified in three children. Those with homozygous/compound heterozygous ABCC8/KCNJ11 mutations were more likely to require a subtotal pancreatectomy CHI (7/10, 70%). Those with paternal heterozygous mutations were investigated with (18)F-Dopa PET-CT scanning and 7/13 (54%) had a focal lesionectomy, whereas four (31%) required subtotal pancreatectomy for diffuse CHI. Those with maternal heterozygous mutations were most likely to achieve remission (5/5, 100%). In 66 with no identified mutation, 43 (65%) achieved remission, 22 (33%) were stable on medical treatment and only one child required a subtotal pancreatectomy. CONCLUSIONS: Rapid genetic analysis is important in the management pathway of CHI; it provides aetiological confirmation of the diagnosis, indicates the likely need for a subtotal pancreatectomy and identifies those who require (18)F-Dopa PET-CT scanning. In the absence of a mutation, reassurance of a favourable outcome can be given early in the course of CHI.

Background: Recessive inactivating mutations in ABCC8 and KCNJ11 (which encode the two subunits of the adenosine triphosphate-sensitive potassium (KATP) channels in β-cells) are the most common cause of medically unresponsive congenital hyperinsulinism (CHI) which requires a near-total pancreatectomy. Methods/Results: a patient born at term with marked macrosomia (5,900 g) presented at the age of 2 h with severe hyperinsulinaemic hypoglycaemia. He failed to respond to treatment with the KATP agonist, diazoxide. An 18FDOPA-PET scan showed intense diffuse uptake of 18FDOPA (consistent with diffuse disease) and genetic analysis of the ABCC8 gene confirmed a compound heterozygote missense ABCC8 mutation (R168C/S606T). However, unexpectedly in this patient the hyperinsulinaemic hypoglycaemia started to improve spontaneously at 7 weeks of age prior to planned pancreatic surgery. Conclusions: This is the first report of a patient with clinically severe autosomal-recessive diffuse CHI due to a compound heterozygous ABCC8 mutation that has resulted in spontaneous resolution at such an early age. Compound heterozygote ABCC8 mutations result in complex interactions, and it is possible that this interaction may modify the potential disease pathogenesis. It is important that physicians are aware of this unusual outcome in order to avoid unnecessary early pancreatic surgery with potential life-long implications. Copyright © 2010 S. Karger AG, Basel.

OBJECTIVE: the phenotype associated with heterozygous HNF4A gene mutations has recently been extended to include diazoxide responsive neonatal hypoglycemia in addition to maturity-onset diabetes of the young (MODY). To date, mutation screening has been limited to patients with a family history consistent with MODY. In this study, we investigated the prevalence of HNF4A mutations in a large cohort of patients with diazoxide responsive hyperinsulinemic hypoglycemia (HH). SUBJECTS AND METHODS: We sequenced the ABCC8, KCNJ11, GCK, GLUD1, and/or HNF4A genes in 220 patients with HH responsive to diazoxide. The order of genetic testing was dependent upon the clinical phenotype. RESULTS: a genetic diagnosis was possible for 59/220 (27%) patients. K(ATP) channel mutations were most common (15%) followed by GLUD1 mutations causing hyperinsulinism with hyperammonemia (5.9%), and HNF4A mutations (5%). Seven of the 11 probands with a heterozygous HNF4A mutation did not have a parent affected with diabetes, and four de novo mutations were confirmed. These patients were diagnosed with HI within the first week of life (median age 1 day), and they had increased birth weight (median +2.4 SDS). The duration of diazoxide treatment ranged from 3 months to ongoing at 8 years. CONCLUSIONS: in this large series, HNF4A mutations are the third most common cause of diazoxide responsive HH. We recommend that HNF4A sequencing is considered in all patients with diazoxide responsive HH diagnosed in the first week of life irrespective of a family history of diabetes, once K(ATP) channel mutations have been excluded.

Aims the aim of this study was to elucidate the entities and the frequency of neonatal diabetes mellitus (NDM) in a large representative database for paediatric diabetes patients in Germany and Austria. Methods Based on the continuous diabetes data acquisition system for prospective surveillance (DPV), which includes 51 587 patients with onset of diabetes before the age of 18 years from 299 centres in Germany and Austria, we searched for patients with onset of diabetes mellitus in the first 6 months of life. Results Ninety patients were identified, comprising 0.17% of all paediatric cases in the DPV registry. This represented an incidence of approximately one case in 89 000 live births in Germany. A monogenic basis for NDM was established in 30 subjects (seven UPD6, 10 KCNJ11, seven ABCC8, two FOXP3, two PDX1, one INS, one EIF2AK3). Pancreatic hypoplasia or agenesis was reported in 10 patients and seven subjects were classified as having Type 1 diabetes by their centres. Transient neonatal diabetes (TNDM) accounted for approximately 10% of all cases with NDM. No aetiology was defined in 41 subjects, which may reflect incomplete genetic testing or novel genetic aetiologies. Conclusion Based on a large database, we identified a higher rate of NDM in Germany than has been reported previously. Full molecular genetic testing should be performed in all patients diagnosed before 6 months of age. © 2010 Diabetes UK.

Background. An infant diagnosed as having hypopituitarism and on adequate hydrocortisone replacement therapy was referred to a tertiary endocrine unit at 5 weeks of age with persistent hypoglycemia that required a high rate of intravenous glucose infusion (up to 18 mg/kg·min-1) to maintain euglycemia.Investigations. A controlled hypoglycemia screen was performed to measure levels of plasma glucose, insulin, C-peptide and 3-β 2-hydroxybutyrate concentrations. The pancreas was analyzed by fluorine-18-L-3,4-dihydroxyphenylalanine (18F-DOPA) PET scan. Genetic analyses were performed on the peripheral blood leukocytes, and loss of heterozygosity within the resected focal lesion of the pancreas was investigated by microsatellite analysis. A glucagon stimulation test helped determine pituitary function, and an MRI of the brain and pituitary gland was performed to define the anatomy of the intracranial structures and the pituitary gland.Diagnosis. Focal form of congenital hyperinsulinism localized to the head of the pancreas, septo-optic dysplasia and pituitary hormone deficiencies.Management. Resection of the focal lesion from the head of the pancreas and hormonal replacement therapy for hypopituitarism. © 2010 Macmillan Publishers Limited. All rights reserved.

BACKGROUND: Neonatal diabetes mellitus (NDM) is a rare monogenic form of diabetes which is diagnosed in the first 6 months of life. Several studies in the last few years provide information on genetic causes for NDM. OBJECTIVE: the aim of this study was to identify all patients with diabetes in the first 6 months of life through the Austrian Diabetes Register, which is available since 1989. A retrospective data analyses was performed to calculate the current incidence of NDM. SUBJECTS AND METHODS: Ten patients were registered with diabetes onset within the first 6 months of life in the Austrian Diabetes Register. Evaluation of detailed clinical data was performed by sending a questionnaire to all diabetes centers. RESULTS: Ten patients from nine different families with NDM were diagnosed in Austria from 1989 until September 2007. Seven patients (one male, six females) had transient NDM (TNDM), three (two males, one female) showed a permanent course [permanent neonatal diabetes mellitus (PNDM)]. One had immunodeficiency, polyendocrinopathy and enteropathy X-linked (IPEX) syndrome and another showed aplasia of the pancreas; no genetic etiology was found in the third case. In three out of seven patients with a transient course of NDM a genetic diagnosis was possible. Two female siblings had activating point mutations in the ABCC8 gene, although one patient had paternal uniparental isodisomy of chromosome 6q24. One patient's family did not consent to genetic testing. CONCLUSIONS: the incidence of NDM in Austria is 1/160 949, with an incidence of 1/ 536 499 for PNDM and 1/229 928 for TNDM.

ATP-sensitive potassium (KATP) channels regulate insulin secretion from pancreatic beta-cells. Gain-of-function mutations in the genes encoding the Kir6.2 and SUR1 subunits of this channel cause neonatal diabetes. We report two novel mutations on the same haplotype (cis), F60Y and V64L, in the slide helix of Kir6.2 in a patient with neonatal diabetes, developmental delay and epilepsy. Functional analysis revealed the F60Y mutation increases the intrinsic channel open probability (Po(0)), thereby indirectly producing a marked decrease in channel inhibition by ATP and an increase in whole-cell KATP currents. When expressed alone, the V64L mutation caused a small reduction in apparent ATP inhibition, by enhancing the ability of MgATP to stimulate channel activity. The V64L mutation also ameliorated the deleterious effects on the F60Y mutation when it was expressed on the same (but not a different) subunit. These data indicate that F60Y is the pathogenic mutation and reveal that interactions between slide helix residues can influence KATP channel gating. © the Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org.

OBJECTIVE: Congenital uterine abnormalities are common and may be associated with developmental renal abnormalities. Mutations of the hepatocyte nuclear factor-1β (HNF1B) gene are associated with renal and uterine abnormalities. We aimed to study the role of HNF1B mutations in a cohort with congenital uterine abnormalities. STUDY DESIGN: We tested 108 probands with uterine abnormalities for HNF1B mutations. We collected clinical information from patient records. RESULTS: Nine of 108 women (8%) had a mutation or deletion in the HNF1B gene. Abnormal HNF1B was found in 18% of the 50 probands who had both uterine and renal abnormalities but in none of the 58 women with isolated uterine abnormalities. CONCLUSION: Mutations of the HNF1B gene are found in women with both uterine and renal abnormalities but are rare in isolated uterine abnormalities. We suggest that HNF1B testing should be performed in patients with both renal and uterine abnormalities, but not in patients with isolated uterine abnormalities.

The ATP-sensitive potassium (K(ATP)) channel is composed of two subunits SUR1 and Kir6.2. The channel is key for glucose stimulated insulin release from the pancreatic beta cell. Activating mutations have been identified in the genes encoding these subunits, ABCC8 and KCNJ11, and account for approximately 40% of permanent neonatal diabetes cases. The majority of patients with a K(ATP) mutation present with isolated diabetes however some have presented with the Developmental delay, Epilepsy and Neonatal Diabetes syndrome. This review focuses on mutations in the K(ATP) channel which result in permanent neonatal diabetes, we review the clinical and functional effects as well as the implications for treatment.

Heterozygous coding mutations in the INS gene that encodes preproinsulin were recently shown to be an important cause of permanent neonatal diabetes. These dominantly acting mutations prevent normal folding of proinsulin, which leads to beta-cell death through endoplasmic reticulum stress and apoptosis. We now report 10 different recessive INS mutations in 15 probands with neonatal diabetes. Functional studies showed that recessive mutations resulted in diabetes because of decreased insulin biosynthesis through distinct mechanisms, including gene deletion, lack of the translation initiation signal, andalteredmRNAstability because of the disruption of a polyadenylation signal. A subset of recessive mutations caused abnormal INS transcription, including the deletion of the C1 and E1 cis regulatory elements, or three different single base-pair substitutions in a CC dinucleotide sequence located between E1 and A1 elements. In keeping with an earlier and more severe beta-cell defect, patients with recessive INS mutations had a lower birth weight (-3.2 SD score vs.-2.0 SD score) and were diagnosed earlier (median 1 week vs. 10 weeks) compared to those with dominant INS mutations. Mutations in the insulin gene can therefore result in neonatal diabetes as a result of two contrasting pathogenic mechanisms. Moreover, the recessively inherited mutations provide a genetic demonstration of the essential role of multiple sequence elements that regulate the biosynthesis of insulin in man.

CONTEXT: Approximately 39% of cases with permanent neonatal diabetes (PNDM) and about 11% with maturity onset diabetes of the young (MODY) have an unknown genetic aetiology. Many of the known genes causing MODY and PNDM were identified as being critical for beta cell function before their identification as a cause of monogenic diabetes. OBJECTIVE: We used nominations from the EU beta cell consortium EURODIA project partners to guide gene candidacy. SUBJECTS: Seventeen cases with permanent neonatal diabetes and 8 cases with maturity onset diabetes of the young. MAIN OUTCOME MEASURES: the beta cell experts within the EURODIA consortium were asked to nominate 3 "gold", 3 "silver" and 4 "bronze" genes based on biological or genetic grounds. We sequenced twelve candidate genes from the list based on evidence for candidacy. RESULTS: Sequencing ISL1, LMX1A, MAFA, NGN3, NKX2.2, NKX6.1, PAX4, PAX6, SOX2, SREBF1, SYT9 and UCP2 did not identify any pathogenic mutations. CONCLUSION: Further work is needed to identify novel causes of permanent neonatal diabetes and maturity onset diabetes of the young utilising genetic approaches as well as further candidate genes.

CONTEXT: the interpretation of novel missense variants is a challenge with increasing numbers of such variants being identified and a responsibility to report the findings in the context of all available scientific evidence. Various in silico bioinformatic tools have been developed that predict the likely pathogenicity of missense variants; however, their utility within the diagnostic setting requires further investigation. AIM: the aim of our study was to test the predictive value of two of these tools, sorting intolerant from tolerant (SIFT) and polymorphism phenotyping (PolyPhen), in a set of 141 missense variants (131 pathogenic, 8 benign) identified in the ABCC8, GCK, and KCNJ11 genes. METHODS: Sixty-six of the mutations caused a gain of protein function, while 67 were loss-of-function mutations. The evolutionary conservation at each residue was also investigated using multiple sequence alignments from the UCSC genome browser. RESULTS: the sensitivity of SIFT and PolyPhen was reasonably high (69% and 68%, respectively), but their specificity was low (13% and 16%). Both programs were significantly better at predicting loss-of-function mutations than gain-of-function mutations (SIFT, p = 0.001; PolyPhen, p < or = 0.0001). The most reliable method for assessing the likely pathogenicity of a missense variant was to investigate the degree of conservation at the affected residue. Eighty-eight percent of the mutations affected highly conserved residues, while all of the benign variants occurred at residues that were polymorphic across multiple species. CONCLUSIONS: Although SIFT and PolyPhen may be useful in prioritizing changes that are likely to cause a loss of protein function, their low specificity means that their predictions should be interpreted with caution and further evidence to support/refute pathogenicity should be sought before reporting novel missense changes.

BACKGROUND: HADH encodes for the enzyme 3-hydroxyacyl-coenzyme a dehydrogenase (HADH) and catalyses the penultimate reaction in the beta-oxidation of fatty acids. All previously reported patients with mutations in HADH gene and hyperinsulinemic hypoglycemia (HH) showed raised plasma hydroxybutyrylcarnitine and urinary 3-hydroxyglutarate. AIMS: the aims of the study were: 1) to report a novel HADH gene mutation not associated with abnormal acylcarnitine or urinary organic acid profile; and 2) to report the novel observation of severe protein-sensitive HH in three patients with HADH gene mutations. RESEARCH DESIGN AND METHODS: the index case presented at 4 months of age with hypoglycemic seizures. Her HH responded to diazoxide, but she continued to have episodes of hypoglycemia even on diazoxide, especially when consuming high-protein foods. RESULTS: Investigations confirmed HH (blood glucose level of 1.8 mmol/liter with simultaneous serum insulin level of 58 mU/liter) with normal acylcarnitines and urine organic acids. Sequencing of the HADH gene identified a homozygous missense mutation (c.562A>G; p.Met188Val). Hydroxyacyl-coenzyme a dehydrogenase activity was significantly decreased compared with controls (index patient, mean +/- sem, 26.8 +/- 4.8 mU/mg protein; controls, 48.0 +/- 8.1 mU/mg protein; P = 0.029) in skin fibroblasts. This patient was severely protein sensitive. Two other children with HH due to HADH gene mutations also demonstrated marked protein sensitivity. CONCLUSIONS: Mutations in the HADH gene are associated with protein-induced HH, and patients with HH due to HADH gene mutations may have normal acylcarnitines and urine organic acids.

CONTEXT: Activating mutations in genes encoding the Kir6.2 (KCNJ11) and SUR1 (ABCC8) subunits of the pancreatic ATP-sensitive K(+) channel are a common cause of permanent neonatal diabetes (PNDM). All Kir6.2 mutations identified to date are missense mutations. We describe here a novel in-frame deletion (residues 28-32) in Kir6.2 in a heterozygous patient with PNDM without neurological problems that are detectable by standard evaluation. OBJECTIVE: the aim of the study was to identify the mutation responsible for neonatal diabetes in this patient and characterize its functional effects. DESIGN: Wild-type and mutant Kir6.2/SUR1 channels were examined by heterologous expression in Xenopus oocytes. RESULTS: the Kir6.2-28Delta32 mutation produced a significant decrease in ATP inhibition and an increase in whole-cell K(ATP) currents, explaining the diabetes of the patient. Tolbutamide block was only slightly reduced in the simulated heterozygous state, suggesting that the patient should respond to sulfonylurea therapy. The mutation decreased ATP inhibition indirectly, by increasing the intrinsic (unliganded) channel open probability. Neither effect was observed when Kir6.2 was expressed in the absence of SUR1, suggesting that the mutation impairs coupling between SUR1 and Kir6.2. Coimmunoprecipitation studies further revealed that the mutation disrupted a physical interaction between Kir6.2 and residues 1-288 (but not residues 1-196) of SUR1. CONCLUSIONS: We report a novel KCNJ11 mutation causing PNDM. Our results show that residues 28-32 in the N terminus of Kir6.2 interact both physically and functionally with SUR1 and suggest that residues 196-288 of SUR1 are important in this interaction.

Hyperinsulinaemic hypoglycaemia (HH) occurs as a consequence of unregulated insulin secretion from pancreatic beta cells. In the newborn period it is the most common cause of severe and persistent hypoglycaemia. As HH is a major risk factor for brain injury and subsequent neurodevelopment handicap, the identification, rapid diagnosis and prompt management of patients with HH is essential if brain damage is to be avoided. Advances in molecular genetics, radiological imaging techniques (such as fluorine-18 L-3, 4-dihydroxyphenylalanine positron emission tomography ((18F)DOPA-PET) scanning) and laparoscopic surgery have completely changed the clinical approach to infants with the severe congenital forms of HH. This review gives an outline of the clinical presentation, the diagnostic cascade, the underlying molecular mechanisms and the management of HH with a particular focus on congenital forms of hyperinsulinism.

Hyperinsulinemic hypoglycemia (HH) is one of the most common reasons for persisting hypoglycemia in newborns infants and children. Its incidence is 1 in 30 000 - 50 000 live births. The clinical manifestation is varying and the prognosis of life depends on the early diagnosis and the efficacy of treatment. Our aim is to present the clinical manifestation and the effect of the treatment in the first three patients in Bulgaria with identified mutations in the ABCC8 gene encoding SUR1 subunit of the KATP channel, causing HH. The first two patients are sisters from a family with consanguinity with manifestation of the disease after birth. They carry one and the same homozygous mutation of ABCC8 gene: R1215W/R1215W (c.c.3643C>T; p.Arg1215Trp), confirming an autosomal recessive form of HH. Both parents are heterozygous carriers of the R1215W mutation. The third patient is a boy who presented his hypoglycemia at the age of 3 months. The gene analysis showed heterozygous state of a novel missense mutation in exon 7 of the ABCC8 gene. The A355T mutation (c.c.1036G>A; p.Ala355Thr) affects a residue conserved from human to chicken and substitutes an uncharged polar amino acid (threonine) for a nonpolar amino acid (alanine). The same heterozygous missense mutation (A355T/N) has been identified in the mother, who is clinically unaffected. The mother is thought to be a carrier of congenital hyperinsulinism and the child is thought to have a recessive form of hyperinsulinism although a paternal mutation has not been identified. The three patients show slight deficiency in the intellectual development and need for special care. The possibility of DNA analysis for mutations of ABCC8 gene gives the opportunity for more precise diagnosis of any child with persisting hypoglycemia.

BACKGROUND: Activating mutations in the GLUD1 gene (which encodes for the intra-mitochondrial enzyme glutamate dehydrogenase, GDH) cause the hyperinsulinism-hyperammonaemia (HI/HA) syndrome. Patients present with HA and leucine-sensitive hypoglycaemia. GDH is regulated by another intra-mitochondrial enzyme sirtuin 4 (SIRT4). Sirt4 knockout mice demonstrate activation of GDH with increased amino acid-stimulated insulin secretion. OBJECTIVES: to study the genotype-phenotype correlations in patients with GLUD1 mutations. To report the phenotype and functional analysis of a novel mutation (P436L) in the GLUD1 gene associated with the absence of HA. Patients and methods Twenty patients with HI from 16 families had mutational analysis of the GLUD1 gene in view of HA (n=19) or leucine sensitivity (n=1). Patients negative for a GLUD1 mutation had sequence analysis of the SIRT4 gene. Functional analysis of the novel P436L GLUD1 mutation was performed. RESULTS: Heterozygous missense mutations were detected in 15 patients with HI/HA, 2 of which are novel (N410D and D451V). In addition, a patient with a normal serum ammonia concentration (21 micromol/l) was heterozygous for a novel missense mutation P436L. Functional analysis of this mutation confirms that it is associated with a loss of GTP inhibition. Seizure disorder was common (43%) in our cohort of patients with a GLUD1 mutation. No mutations in the SIRT4 gene were identified. CONCLUSION: Patients with HI due to mutations in the GLUD1 gene may have normal serum ammonia concentrations. Hence, GLUD1 mutational analysis may be indicated in patients with leucine sensitivity; even in the absence of HA. A high frequency of epilepsy (43%) was observed in our patients with GLUD1 mutations.

OBJECTIVE: Mutations in the ABCC8 gene encoding the SUR1 subunits of the beta-cell K-ATP channel cause neonatal diabetes (ND) mellitus. We aimed to determine the contribution of ABCC8 gene to ND in Poland, to describe the clinical phenotype associated with its mutations and to examine potential modifying factors. PATIENTS: the Nationwide Registry of ND in Poland includes patients diagnosed before 6 months of age. In total 16 Kir6.2 negative patients with ND, 14 permanent and 2 relapsed transient, were examined. MEASUREMENTS: ABCC8 gene mutations were detected by direct sequencing. Mutation carriers' characteristics included clinical data and biochemical parameters. In addition, we performed the hyperinsulinaemic euglycaemic clamp and tested for islet-specific antibodies in diabetic subjects. RESULTS: We identified two probands with permanent ND (one heterozygous F132V mutation carrier and one compound heterozygote with N23H and R826W mutations) and two others with relapsed transient ND (heterozygotes for R826W and V86A substitutions, respectively). One subject, a heterozygous relative with the R826W mutation, had adult onset diabetes. There were striking differences in the clinical picture of the mutation carriers as the carrier of two mutations, N23H and R826W, was controlled on diet alone with HbA(1c) of 7.3%, whereas the F132V mutation carrier was on 0.66 IU/kg/day of insulin with HbA(1c) of 11.7%. The C-peptide level varied from 0.1 ng/ml (F132V) to 0.75 ng/ml (V86A). We also observed a variable insulin resistance, from moderate (M = 5.5 and 5.6 mg/kg/min, respectively, in the two R826W mutation carriers) to severe (M = 2.6 mg/kg/min in the F132V mutation carrier). We were able to transfer two patients off insulin to sulphonylurea (SU) and to reduce insulin dose in one other patient. Interestingly, there was no response to SU in the most insulin resistant F132V mutation carrier despite high dose of glibenclamide. All examined auto-antibodies were present in one of the subjects, the V86A mutation carrier, although this did not seem to influence the clinical picture, as we were able to transfer this girl off insulin. CONCLUSION: Mutations in SUR1 are the cause of about 15% of Kir6.2 negative permanent ND in Poland. The clinical phenotype of SUR1 diabetic mutation carriers is heterogeneous and it appears to be modified by variable sensitivity to insulin.

OBJECTIVE to assess if tooth discoloration is a novel side effect of sulfonylurea therapy in patients with permanent neonatal diabetes due to mutations in KCNJ11. RESEARCH DESIGN AND METHODS a total of 67 patients with a known KCNJ11 mutation who had been successfully transferred from insulin injections onto oral sulfonylureas were contacted and asked about the development of tooth discoloration after transfer. RESULTS Altered tooth appearance was identified in 5 of the 67 patients. This was variable in severity, ranging from mild discoloration/staining (n = 4) to loss of enamel (n = 1) and was only seen in patients taking glibenclamide (glyburide). CONCLUSIONS These previously unreported side effects may relate to the developing tooth and/or to the high local concentrations in the children who frequently chewed glibenclamide tablets or took it as a concentrated solution. Given the multiple benefits of sulfonylurea treatment for patients with activating KCNJ11 mutations, this association warrants further investigation but should not preclude such treatment.

BACKGROUND: Mutations in the KCNJ11 gene encoding the adenosine triphosphate (ATP)-sensitive potassium channel (K(ATP)) subunit Kir6.2 are the most frequent cause of diabetes in infancy. Sulfonylurea (SU) treatment restores insulin secretion in patients with KCNJ11 mutations. MATERIALS AND METHODS: We report a 9-year-old boy who presented at the age of three months with diabetic ketoacidosis. Results Sequencing of the KCNJ11 gene revealed an R201H mutation. Therefore, he was transferred from insulin to oral SU therapy. He required a high-threshold dose before insulin could be discontinued. After transition, a subsequent dose reduction was necessary to avoid hypoglycemia. Improved sustained metabolic control without complications was achieved on a low SU maintenance dose twice daily over 36 months. CONCLUSION: SU therapy is safe for patients with diabetes due to KCNJ11 mutations. The mechanism of a threshold dose and the twice-daily requirement needs further attention.

The beta-cell ATP-sensitive potassium (K(ATP)) channel is a key component of stimulus-secretion coupling in the pancreatic beta-cell. The channel couples metabolism to membrane electrical events bringing about insulin secretion. Given the critical role of this channel in glucose homeostasis it is therefore not surprising that mutations in the genes encoding for the two essential subunits of the channel can result in both hypo- and hyperglycemia. The channel consists of four subunits of the inwardly rectifying potassium channel Kir6.2 and four subunits of the sulfonylurea receptor 1 (SUR1). It has been known for some time that loss of function mutations in KCNJ11, which encodes for Kir6.2, and ABCC8, which encodes for SUR1, can cause oversecretion of insulin and result in hyperinsulinism of infancy, while activating mutations in KCNJ11 and ABCC8 have recently been described that result in the opposite phenotype of diabetes. This review focuses on reported mutations in both genes, the spectrum of phenotypes, and the implications for treatment on diagnosing patients with mutations in these genes.

AIMS/HYPOTHESIS: Heterozygous activating mutations in the pancreatic ATP-sensitive K+ channel cause permanent neonatal diabetes mellitus (PNDM). This results from a decrease in the ability of ATP to close the channel, which thereby suppresses insulin secretion. PNDM mutations that cause a severe reduction in ATP inhibition may produce additional symptoms such as developmental delay and epilepsy. We identified a heterozygous mutation (L164P) in the pore-forming (Kir6.2) subunit of the channel in three unrelated patients and examined its functional effects. METHODS: the patients (currently aged 2, 8 and 20 years) developed diabetes shortly after birth. The two younger patients attempted transfer to sulfonylurea therapy but were unsuccessful (up to 1.1 mg kg(-1) day(-1)). They remain insulin dependent. None of the patients displayed neurological symptoms. Functional properties of wild-type and mutant channels were examined by electrophysiology in Xenopus oocytes. RESULTS: Heterozygous (het) and homozygous L164P K(ATP) channels showed a marked reduction in channel inhibition by ATP. Consistent with its predicted location within the pore, L164P enhanced the channel open state, which explains the reduction in ATP sensitivity. HetL164P currents exhibited greatly increased whole-cell currents that were unaffected by sulfonylureas. This explains the inability of sulfonylureas to ameliorate the diabetes of affected patients. CONCLUSIONS/INTERPRETATION: Our results provide the first demonstration that mutations such as L164P, which produce a severe reduction in ATP sensitivity, do not inevitably cause developmental delay or neurological problems. However, the neonatal diabetes of these patients is unresponsive to sulfonylurea therapy. Functional analysis of PNDM mutations can predict the sulfonylurea response.

Activating mutations in the pore-forming Kir6.2 (KCNJ11) and regulatory sulphonylurea receptor SUR1 (ABCC8) subunits of the K(ATP) channel are a common cause of transient neonatal diabetes mellitus (TNDM). We identified a new TNDM mutation (R826W) in the first nucleotide-binding domain (NBD1) of SUR1. The mutation was found in a region that heterodimerizes with NBD2 to form catalytic site 2. Functional analysis showed that this mutation decreases MgATP hydrolysis by purified maltose-binding protein MBP-NBD1 fusion proteins. Inhibition of ATP hydrolysis by MgADP or BeF was not changed. The results indicate that the ATPase cycle lingers in the post-hydrolytic MgADP.P(i)-bound state, which is associated with channel activation. The extent of MgADP-dependent activation of K(ATP) channel activity was unaffected by the R826W mutation, but the time course of deactivation was slowed. Channel inhibition by MgATP was reduced, leading to an increase in resting whole-cell currents. In pancreatic beta cells, this would lead to less insulin secretion and thereby diabetes.

OBJECTIVE: Congenital hyperinsulinism (CHI) may be due to diffuse or focal pancreatic disease. The diffuse form is associated with an increase in the size of beta-cell nuclei throughout the whole of the pancreas and most commonly results from recessive ATP-sensitive K(+) channel (K(ATP) channel) mutations. Focal lesions are the consequence of somatic uniparental disomy for a paternally inherited K(ATP) channel mutation with enlargement of the beta-cell nuclei confined to the focal lesion. Some "atypical" cases defy classification and show pancreatic beta-cell nuclear enlargement confined to discrete regions of the pancreas. We investigated an atypical case with normal morphology within the tail of the pancreas but occasional enlarged endocrine nuclei in parts of the body and head. RESEARCH DESIGN AND METHODS: the KCNJ11 and ABCC8 genes encoding the K(ATP) channel subunits and microsatellite markers on chromosome 11 were analyzed in DNA samples from the patient and her parents. RESULTS: a mosaic ABCC8 nonsense mutation (Q54X) was identified in the proband. The paternally inherited mutation was present at 90% in lymphocytes and 50% in normal pancreatic sections but between 64 and 74% in abnormal sections. Microsatellite analysis showed mosaic interstitial paternal uniparental isodisomy (UPD) for chromosome 11p15.1. CONCLUSIONS: We report a novel genetic mechanism to explain atypical histological diffuse forms of CHI due to mosaic UPD in patients with dominantly inherited ABCC8 (or KCNJ11) gene mutations.

OBJECTIVE: Neonatal diabetes is a heterogeneous group of disorders with diabetes manifestation in the first 6 months of life. The most common etiology in permanent neonatal diabetes is mutations of the ATP-sensitive K(+) channel subunits; in transient neonatal diabetes, chromosome 6q24 abnormalities are the most common cause. RESEARCH DESIGN AND METHODS: We report a sporadic case of diabetes without ketoacidosis diagnosed on the fourth day of life. RESULTS: Analysis of the KCNJ11 gene found a novel R365H mutation in the proband and her unaffected father. The functional analysis did not support pathogenicity of this variant. When the patient's diabetes remitted in the seventh month of life, the 6q24 region was analyzed and a paternally inherited duplication was identified. CONCLUSIONS: Our case reports a coincidental novel KCNJ11 variant in a patient with transient neonatal diabetes due to a 6q24 duplication, illustrating the difficulty in testing neonates before the clinical course of neonatal diabetes is known.

OBJECTIVE: Neonatal diabetes can result from mutations in the Kir6.2 or sulfonylurea receptor 1 (SUR1) subunits of the ATP-sensitive K(+) channel. Transfer from insulin to oral sulfonylureas in patients with neonatal diabetes due to Kir6.2 mutations is well described, but less is known about changing therapy in patients with SUR1 mutations. We aimed to describe the response to sulfonylurea therapy in patients with SUR1 mutations and to compare it with Kir6.2 mutations. RESEARCH DESIGN AND METHODS: We followed 27 patients with SUR1 mutations for at least 2 months after attempted transfer to sulfonylureas. Information was collected on clinical features, treatment before and after transfer, and the transfer protocol used. We compared successful and unsuccessful transfer patients, glycemic control before and after transfer, and treatment requirements in patients with SUR1 and Kir6.2 mutations. RESULTS: Twenty-three patients (85%) successfully transferred onto sulfonylureas without significant side effects or increased hypoglycemia and did not need insulin injections. In these patients, median A1C fell from 7.2% (interquartile range 6.6-8.2%) on insulin to 5.5% (5.3-6.2%) on sulfonylureas (P = 0.01). When compared with Kir6.2 patients, SUR1 patients needed lower doses of both insulin before transfer (0.4 vs. 0.7 units x kg(-1) x day(-1); P = 0.002) and sulfonylureas after transfer (0.26 vs. 0.45 mg x kg(-1) x day(-1); P = 0.005). CONCLUSIONS: Oral sulfonylurea therapy is safe and effective in the short term in most patients with diabetes due to SUR1 mutations and may successfully replace treatment with insulin injections. A different treatment protocol needs to be developed for this group because they require lower doses of sulfonylureas than required by Kir6.2 patients.

OBJECTIVE: Insulin gene (INS) mutations have recently been described as a cause of permanent neonatal diabetes (PND). We aimed to determine the prevalence, genetics, and clinical phenotype of INS mutations in large cohorts of patients with neonatal diabetes and permanent diabetes diagnosed in infancy, childhood, or adulthood. RESEARCH DESIGN AND METHODS: the INS gene was sequenced in 285 patients with diabetes diagnosed before 2 years of age, 296 probands with maturity-onset diabetes of the young (MODY), and 463 patients with young-onset type 2 diabetes (nonobese, diagnosed

OBJECTIVE: Activating mutations in the KCNJ11 and ABCC8 genes encoding the Kir6.2 and SUR1 subunits of the pancreatic ATP-sensitive K(+) channel are the most common cause of permanent neonatal diabetes. In contrast to KCNJ11, where only dominant heterozygous mutations have been identified, recessively acting ABCC8 mutations have recently been found in some patients with neonatal diabetes. These genes are co-located on chromosome 11p15.1, centromeric to the imprinted Beckwith-Wiedemann syndrome (BWS) locus at 11p15.5. We investigated a male with hemihypertrophy, a condition classically associated with neonatal hyperinsulinemia and hypoglycemia, who developed neonatal diabetes at age 5 weeks. RESEARCH DESIGN AND METHODS: the KCNJ11 and ABCC8 genes and microsatellite markers on chromosome 11 were analyzed in DNA samples from the patient and his parents. RESULTS: a paternally inherited activating mutation (N72S) in the ABCC8 gene was identified in the proband. The mutation was present at 70% in the patient's leukocytes and 50% in buccal cells. Microsatellite analysis demonstrated mosaic segmental paternal uniparental isodisomy (UPD) of 11pter-11p14 in the proband that encompassed the ABCC8 gene and the BWS locus. CONCLUSIONS: We report a patient with neonatal diabetes, hemihypertrophy, and relatively high birth weight resulting from telomeric segmental paternal UPD of chromosome 11, which unmasks a recessively acting gain-of-function mutation in the ABCC8 gene and causes deregulation of imprinted genes at the BWS locus on 11p15.5.

BACKGROUND: KCNJ11 mutations are a common cause of diabetes diagnosed in the first 6 months of life, and approximately 25% of patients have neurological features. Sulphonylureas have been shown to improve glycaemic control and also motor function, but the impact on cognitive function has not been extensively addressed previously. METHODS: the patient had a low birth weight and was found to have diabetes at the age of 2 days. The patient was treated with insulin from diagnosis. The child also had marked developmental delay so that his average functional age was 2.5 years when he was 12 years old. A V59M mutation in KCNJ11 was found on sequencing, resulting in a diagnosis of intermediate developmental delay, epilepsy, neonatal diabetes (DEND) syndrome. Identification of a Kir6.2 mutation allowed insulin injections to be replaced by glibenclamide tablets. RESULTS: This resulted not only in improved glycaemic control (HbA(1c) fell from 8.1 to 6.5%), but also an impressive improvement in many aspects of cognitive function, with the functional age increasing to 4 years within 6 months of treatment change. CONCLUSIONS: This is the first clear report of cognitive function improving in a patient with the neurological features associated with a K(ATP) channel mutation following transfer to sulphonylureas. The finding of cognitive improvement suggests that glibenclamide is likely to be acting directly on the brain and not just on nerve and muscle, improving muscle strength.

OBJECTIVES: Activating mutations in the human KCNJ11 gene, encoding the pore-forming subunit (Kir6.2) of the ATP-sensitive potassium (K(ATP)) channel, are one cause of neonatal diabetes mellitus. In a few patients, KCNJ11 mutations cause a triad of developmental delay, epilepsy, and neonatal diabetes (DEND syndrome).