Association of mutation types and distribution characteristics of dystrophin gene with clinical symptoms in Chinese population

Duchenne muscular dystrophy (DMD) is X-linked disorder caused by mutations in the dystrophin gene. To investigate mutation types and distribution characteristics of dystrophin gene in Chinese DMD patients, we used Multiplex Ligation-Dependent Probe Amplification (MLPA) to analyze the dystrophin gene in 720 DMD patients, their mothers, and 20 normal adult males. Results showed that detection rate was 64.9% (467/720) in all the patients, gene deletion rate was 54.3% (391/720), and gene duplication rate was 10.6% (76/720). The rate of deletion mutant occurred in Exon 45-54 was 71.9% (281/391) in all gene deletion patients; meanwhile, the rate of gene duplication occurred in Exon 1-40 was 82.9% (63/76) in all gene duplication ones. In all the patients with gene deletion and duplication, the rate of DMD and IMD was 90.6% (423/467), and BMD, 9.4% (44/467). This indicates that the main reason of duchenne muscular dystrophy is dystrophin gene deletion mutation, which would occur in any gene unevenly with hot spots of mutation. The location and fragment length of gene deletion and duplication cannot decide the severity of clinical symptoms directly.