Among the genetic mechanisms linked to CHI, inactivating variants of ABCC8 and KCNJ11 (encoding the two subunits of the ATP-sensitive potassium channels in the pancreatic beta cell) are most prevalent [34] but GCK gain-of-function mutants have been described in an increasing number of individuals since 1998 (ESM Table 1). The gene discussed is GCK; the disease is congenital isolated hyperinsulinism.