Identification of Exonic Copy Number Variations in Dystrophin Gene Using Mlpa / Identificarea Variaţiilor Numărului de Copii în Gena Distrofinei Folosind Metoda Mlpa

Duchenne and Becker muscular dystrophies (DMD/BMD) are X-linked progressive muscle disorders determined by mutations of the dystrophin (DMD) gene. Multiplex Ligation - Dependent Probe Amplification (MLPA) is a simple, inexpensive and reliable test for molecular diagnosis of DMD gene mutations. It identifies exonic copy number variations in the DMD gene, but the test should be completed with sequencing analysis in case of single exon deletions/duplications. The aim of this study was to evaluate the efficiency of MLPA as a DMD mutation screening tool in affected males and carrier females, as well as to appreciate the frequency of different types of mutations and to check the validity of the “reading frame rule”. We have used MLPA for the detection of deletions/ duplications in DMD gene in 53 individuals (30 affected males and 23 asymptomatic female relatives) referred for evaluation and genetic counseling due to the clinical suspicion of DMD/BMD. In the affected males (21 DMD and 9 BMD) MLPA had a detection rate of 63.5% (53.5% deletions and 10% duplications). The most frequently deleted exon was exon 45 and the most frequent duplication involved exons 3-5, confirming the presence of the two hotspot mutation regions reported in the literature. Mutations detected in our study have a slightly different location compared to literature data. Reading frame rule was valid in 84% of our cases.