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Context: Congenital hyperinsulinism (HI) is characterized 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. Objective: We investigated the likelihood of finding a genetic cause in childhood-onset HI and explored potential factors leading to 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 (diagnosed with HI < 12 months of age) or childhood-onset (diagnosed at age 1-16 years). We assessed clinical characteristics and the genotypes of individuals with monogenic HI diagnosed in childhood to gain insights into the later age at diagnosis of HI in these children. Results: We identified the monogenic cause in 24% (n=42/173) of the childhood-onset HI cohort; this was significantly lower than the proportion of genetic diagnoses in infancy-onset cases (74.5% [n=1248/1675], P< 0.00001). Most (75%) individuals with genetically confirmed childhood-onset HI were diagnosed before 2.7 years, suggesting these cases represent the tail end of the normal distribution in age at diagnosis. This is supported by the finding that 81% of the variants identified in the childhood-onset cohort were detected in those diagnosed in infancy. Conclusion: We have shown that monogenic HI is an important cause of hyperinsulinism presenting outside of infancy. Genetic testing should be considered in children with persistent hyperinsulinism, regardless of age at diagnosis. [ABSTRACT FROM AUTHOR]

Background: Neonatal diabetes with congenital hypothyroidism (NDH) syndrome is a rare condition caused by homozygous or compound heterozygous mutations in the GLI-similar 3 coding gene GLIS3. Almost 20 patients have been reported to date, with significant phenotypic variability. Case presentation: We describe a boy with a homozygous deletion (exons 5-9) in the GLIS3 gene, who presents novel clinical aspects not reported previously. In addition to neonatal diabetes, congenital hypothyroidism and other known multi-organ manifestations such as cholestasis and renal cysts, he suffered from hyporegenerative anemia during the first four months of life and presents megalocornea in the absence of elevated intraocular pressure. Compensation of partial exocrine pancreatic insufficiency and deficiencies in antioxidative vitamins seemed to have exerted marked beneficial impact on several disease symptoms including cholestasis and TSH resistance, although a causal relation is difficult to prove. Considering reports on persistent fetal hemoglobin detected in a few children with GLIS3 mutations, the transient anemia seen in our patient may represent a further symptom associated with either the GLIS3 defect itself or, secondarily, micronutrient deficiency related to exocrine pancreatic deficiency or cholestasis. Conclusions: Our report expands the phenotypic spectrum of patients with GLIS3 mutations and adds important information on the clinical course, highlighting the possible beneficial effects of pancreatic enzyme and antioxidative vitamin substitutions on characteristic NDH syndrome manifestations such as TSH resistance and cholestasis. We recommend to carefully screen infants with GLIS3 mutations for subtle biochemical signs of partial exocrine pancreatic deficiency or to discuss exploratory administration of pancreatic enzymes and antioxidative vitamins, even in case of good weight gain and fecal elastase concentrations in the low-to-normal range. [ABSTRACT FROM AUTHOR]

Background: Neonatal diabetes mellitus (NDM) is defined as insulin-requiring persistent hyperglycemia occurring within the first 6 months of life, which can result from mutations in at least 25 different genes. Activating heterozygous mutations in genes encoding either of the subunits of the ATP-sensitive K+ channel (KATP channel; KCNJ11 or ABCC8) of the pancreatic beta cell are the most common cause of permanent NDM and the second most common cause of transient NDM. Patients with NDM caused by KATP channel mutations are sensitive to sulfonylurea (SU) treatment; therefore, their clinical management can be improved by replacing insulin with oral agents. Patients and Methods: Seventy patients were diagnosed with NDM between May 2008 and May 2021 at Vietnam National Children's Hospital, and molecular genetic testing for all genes known to cause NDM was performed at the Exeter Genomic Laboratory, UK. Patients with ABCC8 or KCNJ11 mutations were transferred from insulin to oral SU. Clinical characteristics, molecular genetics, and annual data relating to glycemic control, SU dose, severe hypoglycemia, and side effects were collected. The main outcomes of interest were SU dose, SU failure (defined as permanent reintroduction of daily insulin), and glycemic control (HbA1c). Results: Fifty-four of 70 patients (77%) with NDM harbored a genetic mutation and of these; 27 (50%) had activating heterozygous mutations in ABCC8 or KCNJ11. A total of 21 pathogenic mutations were identified in the 27 patients, including 13 mutations in ABCC8 and 8 mutations in KCNJ11. Overall, 51% had low birth weight (below 3rd percentile), 23 (85%) were diagnosed before 3 months of age, and 23 (85%) presented with diabetic ketoacidosis. At diagnosis, clinical and biochemical findings (mean ± SD) were pH 7.16 ± 0.16; HC O 3 − , 7.9 ± 7.4 mmol/L; BE, −17.9 ± 9.1 mmol/L; HbA1C, 7.98% ± 2.93%; blood glucose, 36.2 ± 12.3 mmol/L; and C-peptide median, 0.09 (range, 0–1.61 nmol/l). Twenty-six patients were successfully transferred from insulin to SU therapy. In the remaining case, remission of diabetes occurred prior to transfer. Glycemic control on SU treatment was better than on insulin treatment: HbA1c and blood glucose level decreased from 7.58% ± 4.63% and 19.04 ± 14.09 mmol/L when treated with insulin to 5.8 ± 0.94% and 6.87 ± 3.46 mmol/L when treated with SU, respectively. Conclusions: This is the first case series of NDM patients with ABCC8/KCNJ11 mutations reported in Vietnam. SU is safe in the short term for these patients and more effective than insulin therapy, consistent with all studies to date. This is relevant for populations where access to and cost of insulin are problematic, reinforcing the importance of genetic testing for NDM. [ABSTRACT FROM AUTHOR]

The most common genetic cause of neonatal diabetes and hyperinsulinism is pathogenic variants in ABCC8 and KCNJ11. These genes encode the subunits of the β‐cell ATP‐sensitive potassium channel, a key component of the glucose‐stimulated insulin secretion pathway. Mutations in the two genes cause dysregulated insulin secretion; inactivating mutations cause an oversecretion of insulin, leading to congenital hyperinsulinism, whereas activating mutations cause the opposing phenotype, diabetes. This review focuses on variants identified in ABCC8 and KCNJ11, the phenotypic spectrum and the treatment implications for individuals with pathogenic variants. [ABSTRACT FROM AUTHOR]

HNF4A mutations cause increased birth weight, transient neonatal hypoglycemia, and maturity onset diabetes of the young (MODY). The most frequently reported HNF4A mutation is p.R114W (previously p.R127W), but functional studies have shown inconsistent results; there is a lack of cosegregation in some pedigrees and an unexpectedly high frequency in public variant databases. We confirm that p.R114W is a pathogenic mutation with an odds ratio of 30.4 (95% CI 9.79-125, P = 2 × 10(-21)) for diabetes in our MODY cohort compared with control subjects. p.R114W heterozygotes did not have the increased birth weight of patients with other HNF4A mutations (3,476 g vs. 4,147 g, P = 0.0004), and fewer patients responded to sulfonylurea treatment (48% vs. 73%, P = 0.038). p.R114W has reduced penetrance; only 54% of heterozygotes developed diabetes by age 30 years compared with 71% for other HNF4A mutations. We redefine p.R114W as a pathogenic mutation that causes a distinct clinical subtype of HNF4A MODY with reduced penetrance, reduced sensitivity to sulfonylurea treatment, and no effect on birth weight. This has implications for diabetes treatment, management of pregnancy, and predictive testing of at-risk relatives. The increasing availability of large-scale sequence data is likely to reveal similar examples of rare, low-penetrance MODY mutations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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; p<0·0001). Median duration of diabetes at the time of genetic testing decreased from more than 4 years before 2005 to less than 3 months after 2012. Earlier referral for genetic testing affected the clinical phenotype. In patients with genetically diagnosed Wolcott-Rallison syndrome, 23 (88%) of 26 patients tested within 3 months from diagnosis had isolated diabetes, compared with three (17%) of 18 patients referred later (>4 years; p<0·0001), in whom skeletal and liver involvement was common. Similarly, for patients with genetically diagnosed transient neonatal diabetes, the diabetes had remitted in only ten (10%) of 101 patients tested early (<3 months) compared with 60 (100%) of the 60 later referrals (p<0·0001).Interpretation: Patients are now referred for genetic testing closer to their presentation with neonatal diabetes. Comprehensive testing of all causes identified causal mutations in more than 80% of cases. The genetic result predicts the best diabetes treatment and development of related features. This model represents a new framework for clinical care with genetic diagnosis preceding development of clinical features and guiding clinical management.Funding: Wellcome Trust and Diabetes UK. [ABSTRACT FROM AUTHOR]

Context: Hyperinsulinemic hypoglycemia (HI) can be the presenting feature of Kabuki syndrome (KS), which is caused by loss-of-function variants in KMT2D or KDM6A. As these genes play a critical role in maintaining methylation status in chromatin, individuals with pathogenic variants have a disease-specific epigenomic profile -an episignature., Objective: We evaluated the pathogenicity of three novel partial KDM6A duplications identified in three individuals presenting with neonatal-onset HI without typical features of KS at the time of genetic testing., Methods: Three different partial KDM6A duplications were identified by routine targeted next generation sequencing for HI and initially classified as variants of uncertain significance (VUS) as their location, and hence their impact on the gene, was not known. Whole genome sequencing (WGS) was undertaken to map the breakpoints of the duplications with DNA methylation profiling performed in two individuals to investigate the presence of a KS-specific episignature., Results: WGS confirmed the duplication in proband 1 as pathogenic as it caused a frameshift in the normal copy of the gene leading to a premature termination codon. The duplications identified in probands 2 and 3 did not alter the reading frame and therefore their significance remained uncertain after WGS. Subsequent DNA methylation profiling identified a KS-specific episignature in proband 2 but not in proband 3., Conclusions: Our findings confirm a role for KDM6A partial gene duplications in the etiology of KS and highlight the importance of performing in-depth molecular genetic analysis to properly assess the clinical significance of VUS's in the KDM6A gene., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society.)

Background: Hyperinsulinism/hyperammonemia (HI/HA) syndrome is the second most common type of congenital hyperinsulinism caused by an activating GLUD1 mutation., Objective: The aim of this study was to determine the clinical profile and long-term neurological outcomes in children with HI/HA syndrome., Method: This study is a retrospective review of patients with GLUD1 mutation, treated at two centers in the UK and Russia, over a 15-year period. Different risk factors for neuro-developmental disorders were analysed by Mann-Whitney U test and Fisher's exact P test., Results: We identified 25 cases with GLUD1 mutations (12 males). Median age of presentation was 7 months (12 h-18 months). Hypoglycaemic seizures were the presenting feature in 24 (96%) cases. Twenty four cases responded to diazoxide and protein restriction whilst one patient underwent partial pancreatectomy. In total, 13 cases (52%) developed neurodevelopmental manifestations. Epilepsy (n = 9/25, 36%), learning difficulties (n = 8/25, 32%) and speech delay (n = 8/25, 32%) were the most common neurological manifestation. Median age of presentation for epilepsy was 12 months with generalised tonic-clonic seizures being the most common (n = 4/9, 44.4%) followed by absence seizures (n = 3/9, 33.3%). Early age of presentation (P = 0.02), diazoxide dose (P = 0.04) and a mutation in exon 11 or 12 (P = 0.01) were associated with neurological disorder., Conclusion: HI/HA syndrome is associated with wide spectrum of neurological disorders. These neurological manifestations were more frequent in cases with mutations affecting the GTP-binding site of GLUD1 in our cohort.

Background: Neonatal diabetes mellitus (NDM) is defined as insulin-requiring persistent hyperglycemia occurring within the first 6 months of life, which can result from mutations in at least 25 different genes. Activating heterozygous mutations in genes encoding either of the subunits of the ATP-sensitive K + channel (K ATP channel; KCNJ11 or ABCC8 ) of the pancreatic beta cell are the most common cause of permanent NDM and the second most common cause of transient NDM. Patients with NDM caused by K ATP channel mutations are sensitive to sulfonylurea (SU) treatment; therefore, their clinical management can be improved by replacing insulin with oral agents., Patients and Methods: Seventy patients were diagnosed with NDM between May 2008 and May 2021 at Vietnam National Children's Hospital, and molecular genetic testing for all genes known to cause NDM was performed at the Exeter Genomic Laboratory, UK. Patients with ABCC8 or KCNJ11 mutations were transferred from insulin to oral SU. Clinical characteristics, molecular genetics, and annual data relating to glycemic control, SU dose, severe hypoglycemia, and side effects were collected. The main outcomes of interest were SU dose, SU failure (defined as permanent reintroduction of daily insulin), and glycemic control (HbA1c)., Results: Fifty-four of 70 patients (77%) with NDM harbored a genetic mutation and of these; 27 (50%) had activating heterozygous mutations in ABCC8 or KCNJ11 . A total of 21 pathogenic mutations were identified in the 27 patients, including 13 mutations in ABCC8 and 8 mutations in KCNJ11 . Overall, 51% had low birth weight (below 3rd percentile), 23 (85%) were diagnosed before 3 months of age, and 23 (85%) presented with diabetic ketoacidosis. At diagnosis, clinical and biochemical findings (mean ± SD) were pH 7.16 ± 0.16; HC O 3 - , 7.9 ± 7.4 mmol/L; BE, -17.9 ± 9.1 mmol/L; HbA1C, 7.98% ± 2.93%; blood glucose, 36.2 ± 12.3 mmol/L; and C-peptide median, 0.09 (range, 0-1.61 nmol/l). Twenty-six patients were successfully transferred from insulin to SU therapy. In the remaining case, remission of diabetes occurred prior to transfer. Glycemic control on SU treatment was better than on insulin treatment: HbA1c and blood glucose level decreased from 7.58% ± 4.63% and 19.04 ± 14.09 mmol/L when treated with insulin to 5.8 ± 0.94% and 6.87 ± 3.46 mmol/L when treated with SU, respectively., Conclusions: This is the first case series of NDM patients with ABCC8/KCNJ11 mutations reported in Vietnam. SU is safe in the short term for these patients and more effective than insulin therapy, consistent with all studies to date. This is relevant for populations where access to and cost of insulin are problematic, reinforcing the importance of genetic testing for NDM., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ngoc, Dien, De Franco, Ellard, Houghton, Lan, Thao, Khanh, Flanagan, Craig and Dung.)

Monogenic diabetes and hyperinsulinism are genetically heterogeneous disorders. The determination of the genetic etiology defines the diagnostic subtype, predicts prognosis, and importantly can guide clinical management. This chapter focuses on the processes and methodologies utilized in the diagnostic testing for monogenic diabetes and congenital hyperinsulinism (i.e., Sanger sequencing and targeted next-generation sequencing).

Neonatal diabetes mellitus is a rare monogenic disease with incidence of 1/90,000 newborns. A case of two months aged male infant with life threatening diabetic ketoacidosis is presented with novel ABCC8 gene mutation (p.F577L), successful transition from insulin to sulfonylurea and follow-up of three years., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Neonatal diabetes has not been previously studied in Ukraine. We investigated the genetic etiology in patients with onset of diabetes during the first 9 months of life., Methods: We established a Pediatric Diabetes Register to identify patients diagnosed with diabetes before 9 months of age. Genetic testing was undertaken for 42 patients with permanent or transient diabetes diagnosed within the first 6 months of life (n=22) or permanent diabetes diagnosed between 6 and 9 months (n=20)., Results: We determined the genetic etiology in 23 of 42 (55%) patients; 86% of the patients diagnosed before 6 months and 20% diagnosed between 6 and 9 months. The incidence of neonatal diabetes in Ukraine was calculated to be 1 in 126,397 live births., Conclusions: Genetic testing for patients identified through the Ukrainian Pediatric Diabetes Register identified KCNJ11 and ABCC8 mutations as the most common cause (52%) of neonatal diabetes. Transfer to sulfonylureas improved glycemic control in all 11 patients.

Understanding transcriptional regulation of pancreatic development is required to advance current efforts in developing beta cell replacement therapies for patients with diabetes. Current knowledge of key transcriptional regulators has predominantly come from mouse studies, with rare, naturally occurring mutations establishing their relevance in man. This study used a combination of homozygosity analysis and Sanger sequencing in 37 consanguineous patients with permanent neonatal diabetes to search for homozygous mutations in 29 transcription factor genes important for murine pancreatic development. We identified homozygous mutations in 7 different genes in 11 unrelated patients and show that NKX2-2 and MNX1 are etiological genes for neonatal diabetes, thus confirming their key role in development of the human pancreas. The similar phenotype of the patients with recessive mutations and mice with inactivation of a transcription factor gene support there being common steps critical for pancreatic development and validate the use of rodent models for beta cell development., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)