The most common cause of CHI is inactive mutations of the ATP-sensitive potassium (KATP) channel genes ABCC8 and KCNJ11, which encode the sulfonylurea receptor 1 (SUR1) protein and inwardly rectify potassium channel (Kir6.2) proteins, respectively. The gene discussed is ABCC8; the disease is congenital isolated hyperinsulinism.