ABSTRACT:Objective To investigate the clinical features of Becker muscular dystrophy (BMD) combined with compound heterozygous mutation of titin (TTN ).Methods Clinical features, muscular pathology and genetic examination results of a case of BMD combined with compound heterozygous mutation of TTN were retrospectively analyzed,and the relevant literature was re-viewed.Results The 10 year-old boy had no obvious family history and his clinical phenotype on-ly showed a decrease in upper arm strength.The levels of alanine transaminase,aspartate transar-ninase,lactic dehydrogenase,creatine kinase and creatine kinase isoenzyme in serum were 240, 195,862,16 340 and 234 U·L-1 ,respectively.Among these indicators,serum creatine kinase sig-nificantly increased in this child.The genotype was characterized by nonsense mutation in the ex-on 25 with compound heterozygous deletion of TTN.Immunohistochemical staining showed no expression for Dystrophin N terminus,but partial expression for Dystrophin C and R terminus andβ-Sacroglycan.Conclusion BMD nonsense mutations and TTN mutations in the same geno-type can show different clinical phenotypes.BMD combined with TTN mutations maybe not in-crease the clinical manifestations.%目的：探讨合并肌联蛋白（titin，TTN）基因复合杂合突变贝克型肌营养不良（becker muscular dystrophy， BMD）的临床表型特征。方法结合文献回顾性分析1例合并TTN基因复合杂合突变 BMD患者的临床特点、肌肉病理及基因学检查结果。结果患者为10岁男性儿童，无明显家族史，临床表型仅上臂肌力降低，血清丙氨酸氨基转移酶240 U·L－1，天门冬氨酸氨基转移酶195 U·L－1，乳酸脱氢酶862 U·L－1，肌酸激酶16340 U·L－1，肌酸激酶同工酶234 U·L－1，其中肌酸激酶升高显著，基因型为25号外显子无义突变，合并 TTN复合杂合缺失。肌肉活检免疫组化 Dystrophin-N 端完全不表达，Dystrophin-C、R 及β-Sacroglycan 染色可见部分表达。结论BMD无义突变和TTN突变存在同一基因型可有不同临床表型现象，BMD合并TTN基因突变不一定会加重其临床表现。
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