MT-ND6 and Leber hereditary optic neuropathy: Other pathogenic mtDNA LHON variants have also been described in various studies, with some still awaiting full confirmation for pathogenicity [9,12], but mitochondrial NADH dehydrogenase subunit 1 (MTND1) and mitochondrial NADH dehydrogenase subunit 6 (MTND6) genes of mitochondria are thought to be “mutational hotspots” for LHON-causing mutations, in addition to primary LHON mutations [9,13,14].