ETFDH and multiple acyl-CoA dehydrogenase deficiency: Here, we describe a case of an 11‐year‐old boy, who revealed clinical symptoms, acylcarnitine, and organic aciduria profiles resembling late‐onset MADD, harboring a pathological variant in ETFDH gene and no pathological variants in flavin homeostasis related genes, despite altered plasma levels of flavin cofactors and FAD‐dependent enzymatic activities.