Among these, very long-chain acyl-CoA dehydrogenase deficiency (VLCADD, OMIM 201475), carnitine palmitoyltransferase II deficiency (CPTII, OMIM 255110), and multiple acyl-CoA dehydrogenase deficiency (MADD, OMIM 231680) are most frequently associated with an HCM phenotype. The gene discussed is CPT2; the disease is hyperinsulinemic hypoglycemia, familial, 4.