Detection and analysis of 3 Leber’s hereditary optic neuropathy families carrying tRNALeu(CUN) 12308A>G mutation
WANG Xuan1, LIANG Min1, 2, GUAN Minxin1
1.School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou 325035, China; 2.Medical Laboratory Center, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325015, China
Abstract：Objective: To explore whether the inferred tRNALeu(CUN) 12308A>G mutation affects the phenotypic expression of Leber’s hereditary optic neuropathy (LHON). Methods: Screening of 295 unrelated Han LHON patients and 316 normal controls were performed for mitochondrial mutation genes, and three screened families carrying m.12308A>G mutation and having typical LHON clinical manifestations were analyzed for mitochondrial complete sequence analysis, haplotype analysis and mitochondrial copy number measurement. Results: None of the three pedigrees carried the major primary locus, but a m.12308A>G homogeneous mutation occurred at 44 positions, which was highly conserved on tRNALeu(CUN). The haplotypes of the three probands belonged to East Asian haplotype H2, but the age of onset and the degree of visual impairment were different and no 12308A>G mutation was detected in normal controls. It was found that the mitochondrial copy number of the mutant cells was significantly reduced in the copy number measuremen. Conclusion: The m.12308A>G mutation may be a mutation site associated with LHON. However, the low penetrance of the mutant family indicates that the mutation itself is not sufficient to cause the phenotypic expression of LHON, and that other modification factors (nuclear gene modification, mitochondrial haplotype and environmental factors) have played a role in the pathogenesis of LHON.
