BCKDK Gene (NM_005881.4): A homozygous one-base pair frameshift insertion mutation (c.356_356insC; p.Thr121HisfsTer7) that causes branched-chain ketoacid dehydrogenase kinase deficiency (BCKDK) (OMIM 614923). Here, BCKDK is linked to hyperinsulinemic hypoglycemia, familial, 4.