Clinical study of DMD gene point mutation causing Becker muscular dystrophy

Abstract

Background  DMD gene point mutation, mainly nonsense mutation, always cause the most severe Duchenne muscular dystrophy (DMD). However, we also observed some cases of Becker muscular dystrophy (BMD) carrying DMD point mutation. This paper aims to explore the mechanism of DMD point mutation causing BMD, in order to enhance the understanding of mutation types of BMD.  Methods  Sequence analysis was performed in 11 cases of BMD confirmed by typical clinical manifestations and muscle biopsy. The exon of DMD gene was detected non-deletion or duplication by multiplex ligation-dependent probe amplification (MLPA).  Results  Eleven patients carried 10 mutation types without mutational hotspot. Six patients carried nonsense mutations [c.5002G>T, p.(Glu1668X); c.1615C > T, p.(Arg539X); c.7105G > T, p.(Glu2369X); c.5287C > T, p.(Arg1763X); c.9284T > G, p.(Leu3095X)]. One patient carried missense mutation [c.5234G > A, p.(Arg1745His)]. Two patients carried frameshift mutations (c.10231dupT, c.10491delC). Two patients carried splicing site mutations (c.4518 + 3A > T, c.649 + 2T > C).  Conclusions  DMD gene point mutation may result in BMD with mild clinical symptoms. When clinical manifestations suggest the possibility of BMD and MLPA reveals non?deletion or duplication mutation of DMD gene, BMD should be considered. Study on the mechanism of DMD point mutation causing BMD is very important for gene therapy of DMD.

DOI: 10.3969/j.issn.1672-6731.2015.06.005