摘要目的探讨线粒体脑肌病患者骨骼肌mtDNA在3243及8344位点点突变与发病类型的关系。方法提取患者骨骼肌中的DNA，以两对寡核苷酸为引物行PCR扩增，分别应用BglⅠ和ApaⅠ酶切后，琼脂糖电泳判定。结果 2例患者nt3243位点出现A→G点突变，其中为MELAS和MERRF各一例；2例MERRF患者nt8344位点出现A→G点突变，其中1例同时存在着3243位点突变。结论 nt3243及nt8344位点突变分别与MELAS 和MERRF的发病有关。1例MERRF患者同时存在上述2个位点的突变,这可能与线粒体脑肌病临床表现多样化有关。

abstractsObjective To study the relation between point mutations at nt3243 and nt8344 of muscle mitochondrial DNA from patients with mitochondrial encephalomyopathies and phenotypes. Methods DNA was extracted from muscle specimens from 5 patients with mitochondrial encephalomyopathies and amplified by PCR method, using corresponding oligonucleotide primers. DNA fragments were digested with restriction enzymes BglⅠ and ApaⅠ, then the digested DNA fragments were analyzed with an electrophoresis method.Results The point mutation at nt3243 of mtDNA was found in 2 patients, one with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) and another with myoclonic epilepsy with ragged red fibers (MERRF). The point mutation at nt8344 was found in 2 patients with MERRF, including the one with point mutation at nt3243.Conclusion The point mutation of DNA at nt3243 correlated with MELAS and nt8344 correlated with MERRF. In addition, the detection of point mutations at both nt3243 and nt8344 in a patient with MERRF shows the association of mutation with diversity in clinical manifestations of mitochondrial encephalomyopathies.