ETFDH and multiple acyl-CoA dehydrogenase deficiency: The most common etiology of MADD is mutations in the ETFDH gene, which encodes the electron transfer flavoprotein dehydrogenase (ETFDH) [23,24], relative to which most cases are associated with late onset or RR-MADD (riboflavin responsive-MADD) as is the case for the patients reported in this study.