Molecular Characterization and Management of Congenital Hyperinsulinism: A Tertiary Centre Experience

Congenital hyperinsulinemic hypoglycaemia in a neonate: a rare homozygous ABCC8 gene mutation

Hyperinsulinemic hypoglycaemia (HH) is a heterogeneous disorder causing persistent hypoketotic hypoglycaemia in neonates and infants. Congenital hyperinsulinism (CHI) is a rare cause of HH, resulting from inappropriate insulin secretion by pancreatic β-cells due to genetic defects in key genes, notably ABCC8 and KCNJ11, which encode the SUR1 and Kir6.2 components of the KATP channels, respectively. We present a case of a neonate with congenital HH with persistent hypoglycaemia since birth, which was managed with high-dose glucose infusions, diazoxide and octreotide. A homozygous pathogenic missense variant, c4253G>A (p.Arg1418His) in Exon 35 of the ABCC8 gene was identified in the neonate, confirming CHI. Despite initial refractoriness to treatment, the infant responded to octreotide therapy, cornstarch and careful management with regular feeds and monitoring, avoiding the need for surgical intervention. This case underscores the critical role of genetic diagnosis and timely management in preventing long-term neurological sequelae.

Congenital Hyperinsulinism India Association: An Approach to Address the Challenges and Opportunities of a Rare Disease

India's population complexity presents varied challenges in genetic research, and while facilities have gained traction in tier-1 and -2 cities, reliance on international collaborations often delays such investigations. COVID-19 further exacerbated the issues with such sample sharing. Congenital Hyperinsulinism (CHI) is a rare genetic disorder of pancreatic β-cells causing hypoglycaemia in children due to abnormal insulin secretion. Given India's high birth rate and consanguineous populations, annual CHI cases are estimated to be around up to 10,000, with up to 50% having unexplained genetic causes. Diffuse or atypical lesions in such patients often necessitate near-total-pancreatectomy, risking pancreatic exocrine insufficiency and diabetes, requiring lifelong therapy. Also, novel genetic variations complicate accurate diagnosis, risk assessment, and counselling, emphasising the need for rapid genetic assessment to prevent neurological injuries and inform treatment decisions. Despite significant efforts at many institutes, there are no dedicated organisations for CHI in India. With the implementation of the National Policy for Rare Diseases 2021, we plan to form a non-profit organisation, "Congenital Hyperinsulinism India Association (CHIA)", comprising paediatric endocrinologists, paediatricians, geneticists, and independent researchers. The aims of this association are to generate a national database registry of patients, formulate a parent support group and CHIA consortium, design patient information leaflets, as well as foster genomic collaborations and promote clinical trials. Such steps will help sensitise the health authorities and policy makers, urging them to improve the allocation of health budgets for rare diseases, as well as empower patients and their families, contributing towards a better quality of life.

Non-surgical Treatment May be Appropriate for Most Chinese Children With Monogenic Congenital Hyperinsulinism Based on a Retrospective Study of 121 Patients

Objective: There is a notable absence of extensive Chinese studies involving monogenic congenital hyperinsulinism (CHI). The purpose of this large retrospective Chinese cohort with monogenic CHI from a national children's medical center was to analyze the genetic and clinical characteristics. Methods: We compared clinical characteristics grouped by genotypes based on CHI-targeted next-generation sequencing (tNGS) and performed subgroup analyses by onset time. Results: Totally, 121 non-consanguineous patients were enrolled. Among them, 79 patients (65.3%) had variants in ATP-sensitive potassium channel (KATP) genes (62 heterozygotes and 17 compound heterozygotes), 35 (28.9%) in glutamate dehydrogenase 1 (GLUD1), and 7 (5.8%) in rare genes (hydroxyacyl-CoA dehydrogenase [HADH], glucokinase [GCK], and hepatocyte nuclear factor 4 alpha [HNF4A]). Ten patients had ATP binding cassette subfamily C member 8 (ABCC8) variants (p.G111R), and 12 had GLUD1 variants (p.S498L), suggesting two potential founder variants. Three ABCC8 variants (p.G1478R, p.L580_S581insFASL, and p.S986⁣ ∗ ) and two HNF4A variants (p.R63W and p.V382I) were previously reported to be associated with diabetes. Non-surgical treatment was effective in 65.9% of patients with KATP variants, while in 100% of those with non-KATP variants. For the subgroup of KATP variants, neonatal-onset patients tended to present with mild symptoms (67.9% versus 19.3%), had a higher proportion of surgical intervention (24.5% versus 3.8%), and displayed higher levels of serum insulin and C-peptide than non-neonatal onset ones (p < 0.001). Conclusion: The absence of homozygous variants in KATP genes and a quite higher proportion of GLUD1 variants than previous cohorts, may explain a high response rate of non-surgical treatment in this study. Surgery might be considered for neonatal-onset children, especially when KATP variants were discovered but not for those carried variants reported to cause diabetes in later life. While expanding the genotypic spectrum, we also highlight the clinical significance of genetic screening.

A Focal Form of Diazoxide-resistant Congenital Hyperinsulinism with Good Response to Long-acting Somatostatin

A four-year-old female who was born term via spontaneous vaginal delivery (SVD) with a birth weight of 3.4 kg had an onset of persistent hypoglycaemia at the 6th hour of life. She was diagnosed with congenital hyperinsulinism based on high glucose load, negative ketone and a good response to glucagon. Genetic workup revealed the presence of ATP Binding Cassette Subfamily C Member 8 (ABCC8 genes) mutation which indicated a focal form of congenital hyperinsulinism. She was resistant to the standard dose of oral diazoxide but responded to subcutaneous somatostatin. At the age of 3 years and 6 months, multiple daily injections of somatostatin were replaced with a long-acting monthly somatostatin analogue. With the present treatment, she had better glycaemic control, normal growth and was able to stop tube feeding.

Clinical Profile and Efficacy of Long-Acting Octreotide in Hyperinsulinemic Hypoglycaemia

Introduction

Hyperinsulinemic hypoglycaemia (HH) is characterised by unregulated insulin secretion, leading to persistent non-ketotic hypoglycaemia with a lack of alternate fuel that induces a severe risk for brain damage and neurodevelopmental abnormalities. Octreotide, a somatostatin analogue, has been effectively administered as subcutaneous injections or depot preparations in diazoxide-unresponsive HH.

Methods

Children and infants with HH receiving short-acting octreotide injections were included. Anthropometric values, hypoglycaemic episodes, HbA1C, and side effects were noted from the records and were followed up for 12 months. Informed written consent was obtained from the parents before administration of a single dose of LAR (long-acting octreotide). Based on home-based glucose monitoring (HBGM), the dosage of LAR was modified, and short-acting octreotide was eventually withdrawn. The patients shared the injection's cost for cost-effectiveness. HH affects the quality of life (QoL) if not diagnosed and controlled adequately. A QoL questionnaire was given before starting LAR and after 6 months of receiving LAR, and the changes were noted accordingly.

Results

Twenty-two patients were diagnosed with HH, of which 11 infants and children were included in the study. Mutations were identified in 7 (63.63%) children. Daily octreotide could be tapered and stopped with the addition of sirolimus in one patient with an increasing dose of LAR to maintain euglycaemia. The hypoglycaemic episodes decreased with increasing dose of LAR with a decrease in the severity. Eight (72.7%) patients showed an improved lifestyle on LAR quantified through a QoL questionnaire.

Conclusion

LAR was found effective in reducing hypoglycaemic episodes with no adverse effects. The patient's parent's satisfaction was higher. Given its high cost, this trial achieved cost-effectiveness by sharing a single sitting of LAR injection.

Hyperinsulinism-hyperammonemia syndrome in two Peruvian children with refractory epilepsy

OBJECTIVES

Congenital hyperinsulinism (HI) is a heterogeneous clinical disorder with great variability in its clinical phenotype, and to date, pathogenic variants in 23 genes have been recognized.  Hyperinsulinism-hyperammonemia syndrome (HI/HA) is the second most frequent cause of this disease that shows an autosomal dominant pattern and is caused by an activating mutation of the GLUD1 gene, which responds favorably to the use of diazoxide. HI/HA syndrome presents with fasting hypoglycemia; postprandial hypoglycemia, especially in those with a high protein content (leucine); and persistent mild hyperammonemia. Neurological abnormalities, in the form of epilepsy or neurodevelopmental delay, are observed in a high percentage of patients; therefore, timely diagnosis is crucial for proper management.

CASE PRESENTATION

We report the clinical presentation of two Peruvian children that presented with epilepsy whose genetic analysis revealed a missense mutation in the GLUD1 gene, one within exon 11, at 22% mosaicism; and another within exon 7, as well as their response to diazoxide therapy. To the best of our knowledge, these are the first two cases of HI/HA syndrome reported in Peru.

CONCLUSIONS

HI/HA syndrome went unnoticed, because hypoglycemia was missed and were considered partially controlled epilepsies. A failure to recognize hypoglycemic seizures will delay diagnosis and adequate treatment, so a proper investigation could avoid irreversible neurological damage.