The majority, but not all, Rf responsive MADD patients presented mutations in the gene coding for the FAD‐dependent ETF:QO (ETF:ubiquinone oxidoreductase or ETFDH, ETF dehydrogenase EC 1.5.5.1), embedded in the inner mitochondrial membrane, working as a funnel of electrons deriving from a number of Acyl‐CoAs, aminoacids, and choline.2, 10, 12, 14. This evidence concerns the gene ETFDH and multiple acyl-CoA dehydrogenase deficiency.