Over the last ten years, clinical trials of adeno-associated virus (AAV) gene replacement therapies for the RPE65 (LCA2) [25], CHM-REP1 [26], RPGR [24], CNGA3 [27], VEGFR1/FLT-1 [28], ND4 [29], and MERTK [30] genes have shown significant promise to prevent Leber congenital amaurosis type 2, choroideremia, RPGR-related retinopathy, achromatopsia, wet age-related macular degeneration, Leber hereditary optic neuropathy, and retinitis pigmentosa, respectively. Here, CHM is linked to Leber hereditary optic neuropathy.