CHI has a heterogeneous genetic etiology, and pathogenic variants in ABCC8, KCNJ11, GLUD1, GCK, HADH, SLC16A1, HNF4A, HNF1A, HK1, and INSR genes have been identified to cause isolated, persistent CHI (2). Here, HNF4A is linked to congenital isolated hyperinsulinism.