OPA1 and hereditary optic neuropathy: Since patients with one of the three primary mtDNA mutations (G11778A, T14484C, and G3460A) were not included in the cohort, the actual detection rate of OPA1 mutations in Chinese patients with hereditary optic neuropathy should be even lower, indicating a significantly lower frequency of OPA1 mutations (<6.2%) and a comparatively higher frequency of mtDNA mutations (38%) in Chinese patients with suspected hereditary optic neuropathy compared with French Caucasians (30% for OPA1 and 13% for mtDNA) [21].