Analysis of dystrophin gene in Iranian Duchenne and Becker muscular dystrophies patients and identification of a novel mutation.

Abstract

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are the most frequent muscular dystrophies. Present study aimed to determine the frequency of dystrophin gene alterations in Iranian DMD/BMD patients using molecular techniques. 146 Iranian DMD/BMD patients have been analyzed using two devised sets of multiplex polymerase chain reaction (M-PCR) followed by multiple ligation-dependent probe amplification (MLPA). Two isolated DMD and BMD patients were analyzed by DNA sequencing. 30.9% of patients had single-exon deletion while group and contiguous exon deletions were identified in 41% of the patients. The most numerous exon deletions included exons 45-50 and were identified in the first M-PCR set. Deletion detection rate was 99% in first M-PCR set and remaining deletions (1%) were identified in the second M-PCR set. MLPA analysis showed that there were two exons 3-5 and 41-43 duplications (1.4%) in a BMD and a DMD patient, respectively. Two nonsense mutations including c.633dupA and c.6283 C>T were, respectively, found in a DMD and BMD patient in which c.633dupA has not ever been reported in DMD mutation database and was pathogenic mutation. Besides the report of frequency of dystrophin gene alteration in a subset of Iranian DMD/BMD patients, it was revealed that the proposed M-PCR protocol can be useful in the initial step of molecular diagnosis of DMD/BMD. Exon sequencing would be the final step in determining the mutation status of DMD/BMD patients following MLPA.