Becker muscular dystrophy (BMD) is caused by specific mutations in the DMD gene that causes progressive muscle weakness and primarily affects skeletal and cardiac muscle. Although cardiac involvement is a significant cause of mortality in BMD, the genetic–phenotype correlation for skeletal and cardiac muscles has not been elucidated. Here, we described a 39-year-old man with BMD, who presented with subtle skeletal muscle weakness in the right leg in his 20s and underwent left ventricular restoration for severe dilated cardiomyopathy at the age of 29. He had difficulty climbing stairs after the age of 35. Neither duplication nor deletion of exons was detected by multiplex ligation-dependent probe amplification. A hemizygous c.264 + 1G>A mutation in intron 4 of the DMD was identified by next-generation sequencing. Furthermore, exon 4 skipping of the DMD was confirmed in both skeletal and cardiac muscles evaluated by reverse transcriptase PCR. Endomyocardial and skeletal muscle biopsies revealed dystrophic pathology characterized by muscle fiber atrophy and hypertrophy with a mild degree of interstitial fibrosis. Interestingly, dystrophin immunohistochemistry demonstrated patchy and faint staining of the skeletal muscle membranes but almost normal staining of the cardiac muscle membranes. Western blot analysis revealed a decreased amount of truncated dystrophin in skeletal muscle but surprisingly almost normal amount in cardiac muscle. This case indicates that BMD patients may have severe cardiac dysfunction despite preserved cardiac truncated dystrophin expression.

贝克尔肌营养不良症（BMD）是由DMD基因中的特定突变引起的，该突变导致进行性肌肉无力并主要影响骨骼肌和心肌。尽管心脏受累是导致BMD死亡的重要原因，但尚未阐明骨骼肌和心肌的遗传表型相关性。在这里，我们描述了一个BMD的39岁男子，他在20多岁时右腿出现了微妙的骨骼肌无力，并在29岁时因严重的扩张型心肌病接受了左心室修复。年龄35岁。多重连接依赖探针扩增未检测到外显子的重复或缺失。DMD内含子4中的半合子c.264 + 1G> A突变通过下一代测序鉴定。此外，通过逆转录酶PCR评估，在骨骼肌和心肌中都证实了DMD外显子4的跳跃。心肌内膜和骨骼肌活检显示营养不良性病理，其特征在于肌纤维萎缩和肥大，间质纤维化程度轻。有趣的是，肌营养不良蛋白的免疫组织化学显示骨骼肌膜的斑片和微弱的染色，但心肌膜的染色几乎是正常的。蛋白质印迹分析显示骨骼肌中截短的肌营养不良蛋白数量减少，但心肌中令人惊讶的几乎正常数量。该病例表明，尽管保留了心脏截短的肌营养不良蛋白表达，BMD患者仍可能患有严重的心脏功能障碍。