Moreover, IF is contraindicated in patients with specific rare metabolic or genetic disorders, such as pyruvate carboxylase deficiency (PCD) (159), primary carnitine deficiency (PCD) (160), carnitine-acylcarnitine translocase (CACT) deficiency (161), 3-hydroxyacyl-CoA dehydrogenase deficiencies, including both medium-chain (MCHAD) and long-chain (LCHAD) forms (162, 163), medium-chain acyl-CoA dehydrogenase deficiency (MCADD) (164), very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD) (165), and porphyria (166). The gene discussed is EHHADH; the disease is medium chain acyl-CoA dehydrogenase deficiency.