In parallel, maternally transmitted mtDNA mutations were also described in Leber hereditary optic neuropathy (LHON), with the three most common affecting respiratory chain complex I (m.11778A>G in MTND4, m.14484T>C in MTND6, and m.3460A>G in MTND1) [4, 13, 14 (Table 1). Here, MT-ND4 is linked to Leber hereditary optic neuropathy.