Confirmation Of The G3635a Mutation In The Mitochondrial Nd1 Gene As Causative In Leber's Hereditary Optic Neuropathy

ObjectivesTo analyze the mitochondrial DNA (mtDNA ) mutation of a Chinese family with Leber's hereditary neuropathy (LHON) and investigate the molecular pathogenetic mechanism of the disease. Methods The Patiens are A LHON family, including four affected indivudual and 5 normal family members,and 50 matched healthy controls.(1)The patients and matched healthy controls were collected;(2) Genomic DNA from the peripheral venous blood was extracted and purified using the Wizard Genomic DNA Purification kits;(3) Three primary LHON mutations were elucidated by using mutation specific primer polymerase chain reaction (MSP - PCR) ;(4) The whole sequence were amplified using different two-set PCR systems and the DNA sequences were analyzed,then The sequence results were compared with the updated consensus Cambridge sequence .ResultsWe failed to detect three primary LHON mtDNA mutations (G3460A, G11778A, and T14484C) in the LHON family.The sequence analysis of the complete mitochondrial genomes revealed the existence of G3635A mutations and 31 other points mutations.Among the polymorphisms were nucleotide positions (np) 16189, 185, 189, 709, 8277, 8278insC, 10031, 10398, 11061, 12950, 13681, 16311 and 10978 mutations, which define East Asian haplogroup R11a.The G3635A mutation substitutes an asparagine for a highly conserved serine at ND1 amino acid 110 and this point mutation was only reported in a Russian LHON family. The Eleven missense mutations include one candidate LHON mutation at np 3635(G to A), one novel mutation at np 7868(C toT), and nine known polymorphisms. The C7868T mutation substitues a phenylalanine for a moderate conserved leucine at COâ…¡amino acid 95, These data suggest that novel mutation at np 7868(C toT) may play a synergistic role with the primary mutation G3635A.Conclusion:This is the first time that we discover the G3635A mutation of a LHON family in our country.It is only reported in a single LHON family. Therefore, our results further confirm that the G3635A mutation is the pathogenic mutation point of LHON , and it can be classified as rare primary LHON mutations. In addition,we can infer that novel mutation at np 7868(C toT) may play a synergistic role with the primary mutation G3635A in the LHON onset of the family.