Congenital hyperinsulinism due to compound heterozygous mutations in ABCC8 responsive to diazoxide therapy.

Background: Congenital hyperinsulinism (CHI), a condition characterized by dysregulation of insulin secretion from the pancreatic beta cells, remains one of the most common causes of hyperinsulinemic, hypoketotic hypoglycemia in the newborn period. Mutations in ABCC8 and KCNJ11 constitute the majority of genetic forms of CHI. Case presentation: A term macrosomic male baby, birth weight 4.81 kg, born to non-consanguineous parents, presented on day 1 of life with severe and persistent hypoglycemia. The biochemical investigations confirmed a diagnosis of CHI. Diazoxide was started and progressively increased to 15 mg/kg/day to maintain normoglycemia. Sequence analysis identified compound heterozygous mutations in ABCC8 c.4076C>T and c.4119+1G>A inherited from the unaffected father and mother, respectively. The mutations are reported pathogenic. The patient is currently 7 months old with a sustained response to diazoxide. Conclusions: Biallelic ABCC8 mutations are known to result i n severe, diffuse, diazoxide-unresponsive hypoglycemia. We report a rare patient with CHI due to compound heterozygous mutations in ABCC8 responsive to diazoxide.