It is widely recognized that fibroblasts of MADD patients demonstrate an increased production of reactive oxygen species (ROS) and oxidative stress, as a consequence of two main mechanisms, namely a reduced synthesis of coenzyme Q10, a known ROS scavenger and powerful antioxidant, and a direct leakage of electrons by the misfolded and deficient ETFDH protein, which is therefore unable to effectively transfer electrons to Complex III of the mitochondrial respiratory chain [4]. This evidence concerns the gene ETFDH and multiple acyl-CoA dehydrogenase deficiency.