Molecular genetic diagnosis and treatment of congenital hyperinsulinism: results of observation of patients with variants in the genes ABCC8 and KCNJ11

Congenital hyperinsulinism is a rare hereditary disease characterized by inadequate hypersecretion of insulin by pancreatic β-cells, clinically manifested by persistent hypoglycemia, which poses a great threat to patient survival and a high risk of developing severe neurological complications. The article presents the results of clinical, hormonal and molecular genetic examination and treatment of 10 patients with congenital hyperinsulinism caused by mutations in the genes of ATP-dependent potassium channels (KCNJ11, ABCC8), hospitalized in Saint Petersburg State Pediatric Medical University clinic in 2010–2023. In all the studied patients, the disease manifested from the 1^st to the 3^rd day of life, and the median age of diagnosis of congenital hyperinsulinism in the study group was 1 month (min 14 days; max 3 years 9 months). In 8 out of 10 patients, a severe course of hypoglycemic syndrome was noted at the onset of the disease. According to the molecular genetic investigation results, 8 different mutations were identified: in the KCNJ11 (2/8) and ABCC8 (6/8) genes. Identical variants were found in two pairs of related patients. In children with mutations in the ABCC8 gene (n = 8), 2 variants with unknown clinical significance were identified, which were not previously described in allelic databases and scientific literature. According to the analysis of anamnestic and clinical and laboratory data, 80.0% of children, including patients with new, previously not described in the scientific literature, variants in the ABCC8 gene have a severe progressive course of congenital hyperinsulinism, requiring the appointment of insulinostatic therapy.