A splicing mutation in the DMD gene detected by next-generation sequencing and confirmed by mRNA and protein analysis

Background: Dystrophinopathies, either the severe Duchenne Muscular Dystrophy (DMD) or the milder Becker Muscular Dystrophy (BMD), are X-linked recessive disorders caused by mutations in the DMD gene. DMD is one of the longest human genes. Large deletions or duplications account for 60-80% of the mutations. Remaining anomalies consist in point mutations or small rearrangements. Routinely, the molecular diagnosis is done by a Multiplex Ligation-dependent Probe Amplification (MLPA) or array Comparative Genome Hybridization (aCGH), followed, if negative, by Sanger sequencing of all exons.

Methods: In this study, massive parallel sequencing (MPS) or next generation sequencing (NGS) was used to make a rapid and costless molecular diagnosis in a young boy suspected of DMD.

Results: A small deletion: NM_004006.2:c.2803+5_2803+8del was identified. The diagnosis was performed in one single manipulation and within a week. The consequence of this intronic mutation is a skipping of exon 21 confirmed by mRNA and protein analysis.

Conclusions: NGS appears to be an efficient new strategy in DMD molecular diagnosis. It highlights the major evolution of the diagnostic strategy towards high throughput technologies, where bioinformatics analysis becomes the real challenge for variations detection. This is the first study reporting in vivo impact of this intronic mutation.