Typically children with diffuse CHI have homozygous recessive or compound heterozygous mutations in the ABCC8 or KCNJ11 genes (which encode the SUR1 and Kir6.2 proteins respectively – the two components of the ATP-sensitive K+ (KATP) channel of the pancreatic β-cell) [3], [4]. Here, ABCC8 is linked to congenital isolated hyperinsulinism.