GTPBP3 and mitochondrial disease: Other nuclear genes that are implicated in mitochondrial diseases in various organs include the nuclear-encoded mitochondrial transcription factor B1 (TFB1M)10, GTP-binding protein 3 (GTPBP3)11, mitochondrial translational optimization protein 1 (MTO1)12, and the mitochondrial tRNA-specific modification enzyme tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase (TRMU)13.