Consistent with this notion, an extremely rare, lethal, and multisystemic metabolic derangement was linked to damaging mutations of the critical mitochondrial fission protein, DRP1 [16,17,18,19], although dominant mutations in DNM1Lgene can also cause dominant optic atrophy (DOA) with a relatively mild phenotype [20]. The gene discussed is DNM1L; the disease is autosomal dominant optic atrophy.