By combining published reports together with data from five international molecular genetic screening laboratories in the UK, Denmark, France, and the United States of America, we now report 953 pathogenic ABCC8 and KCNJ11 variants (Tables S1–S6) and discuss the role of these genes in congenital hyperinsulinism (CHI) and monogenic diabetes. The gene discussed is ABCC8; the disease is congenital isolated hyperinsulinism.