Variants in genes MT-ND1 4216T > C, MT-ND5 12633C > A and 13368G > A, MT-ND4 11251A > G and 11719G > A, MT-CO1 7028C > T, MT-CYB 15452C > A and 14766C > T, MT-RNR2 1888G > A, MT-ATP6 8856G > A and MT-ND2 4917A > G were described as secondary LHON mutations in Parkinson’ disease, Leight syndrome, or Leber’s hereditary optic neuropathy[27-29]. The gene discussed is MCAT; the disease is Leber hereditary optic neuropathy.