Contrary to secondary coenzyme Q10 deficiency in MADD fibroblasts, Wen et al. reported no significant decrease in coenzyme Q10 levels in the muscle tissue of MADD patients; rather, there was an increase in total coenzyme Q10 levels in the muscle tissue of RR-MADD patients with ETFDH gene mutations [33]. Here, ETFDH is linked to multiple acyl-CoA dehydrogenase deficiency.