Genotype analyses of CPT2 in patients suffering from CPT II deficiency identified three polymorphisms associated with amino acid substitutions: [c.1102 G>A (p.V368I)] (heterozygous), [c.1102 G>A (p.V368I)] (homozygous), and [c.1055 T>G (p.F352C)] (heterozygous) + [c.1102 G>A (p.V368I)] (homozygous). Here, CPT2 is linked to hyperinsulinemic hypoglycemia, familial, 4.