Journal articles
Wakeling M, Owens NDL, Hopkinson JR, Johnson MB, Houghton JAL, Dastamani A, Flaxman CS, Wyatt RC, Hewat TI, Hopkins JJ, et al (In Press). A novel disease mechanism leading to the expression of a disallowed gene in the pancreatic beta-cell identified by non-coding, regulatory mutations controlling HK1.
Nature GeneticsAbstract:
A novel disease mechanism leading to the expression of a disallowed gene in the pancreatic beta-cell identified by non-coding, regulatory mutations controlling HK1
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.
Abstract.
Hewat TI, Johnson M, Flanagan S (In Press). Congenital hyperinsulinism: current laboratory-based approaches to the genetic diagnosis of a heterogeneous disease. Frontiers in Endocrinology
Hopkins J, Childs A, Houghton J, Hewat T, Atapattu N, Johnson M, Patel K, Laver T, Flanagan S (In Press). Hyperinsulinaemic hypoglycaemia diagnosed in childhood can be monogenic.
The Journal of Clinical Endocrinology & MetabolismAbstract:
Hyperinsulinaemic hypoglycaemia diagnosed in childhood can be monogenic
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
Abstract.
Hewat TI, Laver T, Houghton J, Mannisto J, Alvi S, Brearey S, Cody D, Dastamani A, de los Santos la Torre M, Murphy N, et al (In Press). Increased referrals for congenital hyperinsulinism genetic testing in children with trisomy 21 reflects the high burden of non-genetic risk factors in this group. Pediatric Diabetes
Hewat TI, Yau D, Jerome JCS, Laver TW, Houghton JAL, Shields BM, Flanagan SE, Patel KA (2021). Birth weight and diazoxide unresponsiveness strongly predict the likelihood of congenital hyperinsulinism due to a mutation in ABCC8 or KCNJ11.
European Journal of Endocrinology,
185(6), 813-818.
Abstract:
Birth weight and diazoxide unresponsiveness strongly predict the likelihood of congenital hyperinsulinism due to a mutation in ABCC8 or KCNJ11
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.
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