目的 ·通过分析 2个中国汉族假肥大型进行性肌营养不良家系的基因变异，提高对本病的认识。方法 ·回顾性分析 2个假肥大型进行性肌营养不良家系中先证者的临床特征，以及先证者及其亲属的多重连接探针扩增（ multiplex ligation-dependent probe amplification，MLPA）检测结果。结果 · 3个携带抗肌萎缩蛋白基因（ dystrophin gene，DMD基因）变异的假肥大型进行性肌营养不良先证者均有血清肌酸激酶异常升高，家系 1中异卵双生的兄弟 2人均为 DMD基因 8～ 9号外显子缺失，其母该位点未见异常。家系 2中异卵双生之弟为 DMD基因 48～ 51号外显子重复，其母为该位点的杂合变异。结论 ·①异卵双胎存在相同 DMD基因突变的家系，若其母亲外周血基因检测正常，则提示其母亲可能为该突变的生殖腺嵌合体，再次生育时须进行产前基因诊断来降低后代患假肥大型进行性肌营养不良的风险。② DMD基因 48～ 51号外显子重复为致病突变。

Objective · To deepen the understanding of Duchenne/Becker muscular dystrophyinvestigating dystrophin (DMD) gene variants in 2 Chinese Han families with this disease. Methods · Retrospective analysis of the clinical characteristics of the probands in two families with Duchnne/ Becker muscular dystrophy and the results of multiplex ligation-dependent probe amplification (MLPA) for the probands and their relatives was performed. Results · Three probands were identifiedsignificantly-elevated creatine kinase levels. Two probands in family one are fraternal twin brothers with the same deletions of exons 8-9, while their mother has no abnormality at this site. The proband in family two is the little brother in a pair of fraternal twins with duplication of exons 48-51, and his mother has heterozygous duplication of exons 48-51. Conclusion · ① The presence of the same DMD gene mutation in the fraternal twins suggests that the mother may be a gonad chimera with this mutation if her gene detection of peripheral blood is normal. The mother must undergo prenatal gene diagnosis to reduce the risk of Duchenne/Becker muscular dystrophy in her offsprings. ② The exons 48-51 duplication of DMD gene is pathogenic mutation.