MCAT and Leber hereditary optic neuropathy: [17], [18] and references therein). The MT-ND1 and MT-ND6 genes were found to be mutational hotspots for LHON patients without the three primary mutations in European populations [19], [20]. Similarly, we found that the MT-ND1 and MT-ND5 genes are mutational hotspots in Chinese suspected LHON patients with a family history but lacking the three primary mutations [21].