KCNJ11 and congenital isolated hyperinsulinism: The most common forms of CHI are due to defects in ABCC8 and KCNJ11, which encode the ATP-sensitive potassium (KATP) channel subunits of the sulfonylurea receptor (SUR1) protein and inwardly rectify potassium channel (Kir6.2) proteins, respectively (13).