ETFDH and multiple acyl-CoA dehydrogenase deficiency: Multiple acyl-coenzyme A dehydrogenase deficiency (MADD) (OMIM#231680) is a fatty acid oxidation metabolic disorder caused by a gene defect in mitochondrial electron transport flavoprotein (ETF) or electronic transfer flavoprotein-ubiquinone oxidoreductase [ETF-QO, also known as electronic transfer flavoprotein dehydrogenase (ETFDH)].