KCNJ11 and hyperinsulinism: Loss-of-function mutations of β-cell KATP channel subunits (SUR1, ABCC8, OMIM accession number 600509; and Kir6.2, KCNJ11, OMIM 600937; GenBank, http://www.ncbi.nlm.nih.gov/) underlie congenital hyperinsulinism (HI) in humans [3–7], a genetic disease characterized by relative hyperinsulinemia and hypoglycemia [8].