中文摘要：

目的检测线粒体脑肌病伴乳酸血症和卒中样发作（MELAS）综合征家系患者线粒体DNA的突变情况。方法采集2例MELAS家系患者和100例体检健康者（正常对照）的外周血，采用PCR法扩增22个线粒体tRNA基因，变性高效液相色谱分析技术对PCR产物进行突变筛选，对出现异常峰型的tRNA基因进行核苷酸序列测定，确定突变位点。结果与正常对照相比，2例MELAS患者tRNA-Val基因发生杂合突变A1640T／A。结论MELAS病家系患者线粒体DNA的tRNA-Val基因杂合突变A1640T／A可能是其MELAS的致病原因。

英文摘要：

Objective To investigate the mutations of mitochondrial DNA（mt DNA） in a family pedigree of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes（MELAS）. Methods The peripheral blood of 2 patients with MELAS and 100 healthy people（control group） was collectecL PCR was used to amplify the whole tRNA genes of 22 mitochondria, which were then screened by denaturing high-performance liquid chromatography. The tRNA gene with abnormal spike was sequenced, and the mutation site was determined. Results Compared with control group, there was a heteroplasmic A1640T/A mutation in tRNA-Val gene in patients with MELAS. Conclusion tRNA-Val gene mutation A1640T/A of mtDNA in a family pedigree of MELAS might be a pathogeny of MELAS.