Monthly Archives: March 2026

BC368 – Biochemistry of the Cell II

Case Study #5: Focal ABCC8-Related Congenital Hyperinsulinism

Background:

Congenital hyperinsulinism is the leading cause of persistent hypoglycemia in infants and children. In newborns, it can present within hours to days after birth and may cause seizures, hypotonia, poor feeding, or apnea. Focal congenital hyperinsulinism accounts for about 30% to 40% of cases and is caused by a heterozygous ABCC8 or KCNJ11 pathogenic variant inherited from the father together with somatic loss of the maternal 11p15 region in pancreatic tissue. Unlike diffuse disease, focal disease is confined to a limited region of the pancreas and can often be cured if that region is accurately localized and surgically removed.

Case Summary:

A male neonate born after a 40-week term and with a birth weight of 3.16 kg (6.97 lb) was hospitalized in the neonatal intensive care unit for transient tachypnea. On the fifth day of hospitalization, he developed a convulsion and was found to have severe persistent hypoglycemia. There was no maternal history of diabetes. He was started on continuous glucose infusion at 8 to 10 mg/kg/min, and diazoxide was added and titrated to 20 mg/kg/day in an attempt to maintain normoglycemia.

Laboratory Discoveries:

During hypoglycemia, the infant’s plasma glucose was 44 mg/dL, beta-hydroxybutyrate was 0.16 mmol/L with a listed normal value of greater than 1.8 mmol/L, and insulin was 3.7 μU/mL with a stated laboratory reference range of 2.6 to 24.9 μU/mL.…