Genetically, variants in at least nine genes have been identified as causes of CHI; ATP-Binding Cassette, subfamily C, member 8 (ABCC8) and Potassium Channel, Inwardly rectifying, subfamily J, member 11 (KCNJ11), which constitute the K+ATP channel of the beta cell, accounts for most cases (9, 10). The gene discussed is KCNJ11; the disease is congenital isolated hyperinsulinism.