MTRFR and mitochondrial DNA depletion syndrome, encephalomyopathic form with methylmalonic aciduria: Although multiple phenotypes have been shown to be associated with mutations in C12orf65 gene, including early-onset optic atrophy, encephalomyopathy, peripheral neuropathy, intellectual disability, and spastic paraparesis (56–58), the function of C12orf65 gene remains largely unknown.