MT-ND4 and Leber hereditary optic neuropathy: Bonnet C et al., reported that allotopic expression helped to restore respiratory complex I/V activity, ATP synthesis, and the cell survival rate in cultured skin fibroblasts isolated from two LHON patients harboring mutations in ND1 (3460) or ND4 (11,778) and one NARP (neurogenic muscle weakness, ataxia and retinitis pigmentosa) patient with the T8993G ATP6 mutation [30,31].