Familial Hyperinsulinism Caused by an Activating Glucokinase Mutation

Abstract

Spontaneous hyperinsulinemic hypoglycemia in adults is most frequently caused by sporadic, solitary pancreatic beta-cell tumors, whereas hyperinsulinemic hypoglycemia in childhood is commonly caused by generalized beta-cell dysfunction.¹ Mutations in the beta-cell sulfonylurea-receptor (SUR1) gene or inward-rectifying potassium-channel (Kir6.2) gene were found in some patients.^2-7 A distinct syndrome of hyperinsulinism with hyperammonemia was recently described,^8,9 apparently caused by mutations in the glutamate dehydrogenase gene.¹⁰ However, many sporadic and familial cases of hyperinsulinism remain unexplained. Some may be due to somatic mutations in other genes, as suggested by reports of autosomal dominant familial hyperinsulinism that was not genetically linked to the SUR1 or Kir6.2 locus.^11,12