Molecular Genetic Analysis of a DMD Frameshift Mutation in a Boy with Duchenne Muscular Dystrophy by MLPA and Sanger Sequencing.

Abstract

Duchenne muscular dystrophy (DMD) is an X-linked recessive neuromuscular disease that is characterized by progressive proximal muscle weakness and pseudohypertrophy. Currently, genetic diagnosis of DMD relies largely on multiplex ligation-dependent probe analysis (MLPA) and Sanger sequencing to identify pathogenic mutations. This study aimed to confirm the genetic etiology of a boy presenting with clinical manifestations that are highly indicative of DMD. A 14-year-old boy with heart failure and extreme muscle weakness along with his family members was recruited for this study. DNA from each participant was isolated from peripheral blood samples. We used MLPA to detect the deletion or duplication mutations of the DMD gene and Sanger sequencing to verify the missing region of the exon in the proband. Furthermore, the functional role of the mutation was assessed using bioinformatics. We found that the proband carried a small deletion in the DMD gene (c.6808_6811delTTAA). The deletion of those four nucleotides resulted in a frameshift mutation and a premature nonsense codon, which resulted in a truncated dystrophin that lost its most critical function and underwent post-transcriptional degradation. Our study demonstrated that MLPA, in combination with Sanger sequencing, is a reliable and practical approach for the genetic diagnosis of DMD, which is a significant step towards developing personalized therapy.