中文摘要：

目的 研究携带A3243G突变的家系成员的临床症状特点以及与A3243G突变负荷的关系.方法 收集42个携带A3243G突变的核心家系,对他们的临床表现、实验室检查和线粒体DNA 3243位点点突变检测结果进行分析.结果 （1）肌无力、癫痫发作、多毛、头痛、认知障碍、消瘦和身材矮小是A3243G突变家族中先证者最常见的临床症状,而且这些临床症状多同时存在.在实验室检查中,血乳酸、丙酮酸及MRI检查多有异常 （2）A3243G突变家族中的携带者大多表现正常,肌无力、消瘦和身材矮小是他们最常见的临床症状 （3）在先证者组中,尿液A3243G突变负荷高于血液（t=-15.06,P＜0.001）,在先证者母亲组中,尿液A3243G突变负荷也高于血液（z=-6.241,P＜0.001） （4）先证者组血液和尿液中的A3243G突变负荷约是母亲组的2倍.结论 携带A3243G突变患者表型差异很大,先证者组的临床表现和实验室检查结果均较母亲组严重,可能与A3243G突变负荷有一定关系.

英文摘要：

Objective A3243G mutation in mitochondrial DNA is the most common pathogenic point mutation causing a variety of phenotypes.The clinical phenotype and the relationship between the clinical phenotype and the ratio of A3243G mutation were studied in the members from nuclear families carrying A3243G mutation.Methods A total of 42 families carrying A3243G mutation were recruited and their clinical symptoms,laboratory results and the ratio of A3243G analyzed.Result （ 1 ） In probands,myopathy,seizure,hirsutism,headache,cognitive impairment,weight loss and short stature were the most common clinical features.They tended to occur simultaneously.Lactic acid,pyruvate and MRI were abnormal in most probands （ 2 ） most carriers had a normal phenotype.Myopathy,weight loss and short stature were their most common clinical features （3）the ratio of A3243G mutation in urine was higher than that in blood in probands （ t = - 15.06,P 〈 0.001 ）.And the ratio of A3243G mutation in urine was higher than that in blood in their mothers（z = -6.241,P 〈0.001 ） （4） the ratio of A3243G mutation in probands was 2-fold higher than that in their mothers in both blood and urine.Conclusion The phenotype of patients carrying A3243G mutatiom is varied.The clinical symptoms and laboratory results of probands are worse than those of mothers.It is probably due to a higher mutation ratio of m.3243 A 〉 G in their tissues.