[Analysis on the effect of secondary mutations on Leber's hereditary optic neuropathy]

To investigate the effect of secondary mutations on Leber's hereditary optic neuropathy (LHON).Three primary and 24 secondary mutations were identified in 4 Chinese families which included male offspring.All of the four pedigrees carried classic LHON mutations at nucleotide (nt) 11778, and did not carry any point of 24 secondary mutations. Nevertheless many polymorphic points were found in the nearby fragments of these pedigrees, such as 5178, 5108, 3705, 3721, 13734, etc.Male offspring sequences should be analyzed in pedigrees with LHON to avoid the influence of familial inheritance characteristic which mitochondrial DNA polymorphism carried. Existence of the "repair genes" may affect the development of LHON.