中文摘要：

目的揭示一个Leber遗传性视神经病变（Leber＇s hereditary optic neuropathy，LHON）家系的遗传基础。方法对家系成员提取线粒体DNA（mtDNA），直接进行测序分析，用分子克隆法为每个人构建单克隆群，再用高分辨熔解曲线技术和DNA测序的方法，对家系中成员的单克隆群分析统计，计算该家系成员的线粒体DNA突变比例。结果该家系患者mtDNA上11778位核苷酸发生G到A的突变。家系成员中G11778A突变比例分别为：先证者（112）91．67％；父亲（12）0％；3位母系家属正常人依次为：（11）90．83％、（111）53．16％、（113）49．16％。结论G11778A的同质体（即：突变比例达到90％以上）女性仍可不患Leber遗传性视神经病变，该女性后代的平均突变比例远小于先前的报道。

英文摘要：

Objective To investigate the genetic basis for a Chinese pedigree with Leber＇s hereditary optic neuropathy （LHON）. Methods Direct DNA sequence was performed for 3 candidate mtDNA sites. High resolution melting and sequencing were carried out to analyse the proportion of mutant mtDNA of each member in the LHON pedigree afterwards. Results A single nucleotide substitution of G for A was found at 11778th of mtDNA. The proportion of mtG11778A for the proband （Ⅱ2）, his father （Ⅰ2）, and three unaffected maternal members （Ⅱ,Ⅲ, Ⅱ3） were 91.67%, 0%, 90.83%, 53.16%, 49.16%, respectively. Conclusion Our study found that the female GI1778A mtDNA mutation carrier Ⅱ, who contains more than 90% G11778A mtDNA mutation, could be unaffected, and her children＇s average proportion of mutant mtDNA was far lower than the previous reports.