The molecular basis of CHI involves defects in key genes (ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF1A, HNF4A, UCP2, HK1, PGM1 and PMM2) which regulate insulin secretion. Here, HNF1A is linked to congenital isolated hyperinsulinism.