Identification of two rare mutations c.1318G>A and c.6438+2T>G in a Chinese DMD family as genetic markers

Background Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive disorder with no effective treatment, which underscores the importance of avoiding the birth of children with DMD by identifying pathogenic mutations and obtaining an accurate prenatal diagnosis. Objective The objective of this study was to analyze the genetic defect of a Chinese family where all male patients have died of DMD. Methods Multiplex ligation dependent probe analysis (MLPA) and next-generation sequencing (NGS) were employed to detect DMD mutations. The candidate mutations were then validated by Sanger sequencing. In vitro splicing assay was further conducted to examine the potential effect of the novel DMD splice site mutation on splicing. Results We found that two rare DMD mutations c.1318G>A and c.6438+2T>G passed from generation to generation among female carriers and they may be used as genetic markers in the Chinese DMD family. In vitro splicing assay further revealed that the novel classical splice site mutation c.6438+2T>G gave rise to a new donor splice site, which resulted in a frame shift of the transcripts and a premature termination at position 2159 in exon 45 (p.Y2144Nfs*16). Conclusion We found that two co-inherited mutations passed from generation to generation in female carriers and they may be used as genetic markers in the Chinese DMD family. Our findings not only expanded the DMD mutation spectrum, but also provided an important basis for identifying of female carriers and avoiding the birth of affected male children in this DMD family.