According to the variable clinical manifestations, the phenotypes of dystrophinopathy were classified as Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). The aim of this study was to summarize the characteristics of genotypes and the expression of dystrohpin in patients with dystrophinopathy, to investigate the relationships between them and phenotypes.

Two hundred and four male patients with dystrophinopathy who presented to the Peking University First Hospital between August 2013 and August 2017 were enrolled. Their diagnosis were confirmed by gene tests, and the out-of-frame mutations were analyzed by means of the Leiden Dystrophin genetic database. Muscle biopsies were performed in 78 patients, and the levels of expression of dystrohpin were assigned by a 0–5 scale. All the values were calculated and processed using the SPSS 17.0 statistical package. Descriptive statistics were carried out when appropriate. The rank sum test was used to make difference analysis of the expression of dystrohpin between DMD and BMD. P<0.05 means statistically significant.

In all the patients, 181 were DMD and 23 were BMD. Genetic analysis revealed that 162 (79.4%) were deletions, 23 (11.3%) were duplications and 19 (9.3%) were small mutations. Among the 185 deltion/duplication mutations, 89.1% patients were in coincidence with the reading-frame hypothesis. With immumohistochemical staining, the median scores of the expression of dystrophin-N, R and C were 0, 2 and 1 respectively in DMD, while they were 3, 4 and 4 respectively in BMD. The difference of the scores between DMD and BMD is statistically significant, with N (P=0.010), R (P=0.031),C (P=0.000) and the total scores (P=0.001) respectively.

The genotypes overlapped between different phenotypes of dystrophinopathy. There were significant differences between the expressions of dystrophin of DMD and BMD. These findings may be beneficial for the selection of therapeutic regimens and rehabilitation therapy of patients with dystrophinopathy.