Molecular Diagnosis of Duchene/Becker Muscular Dystrophy: Analysis of Exons Deletion and Carrier Detection

Objective: Duchenne and Becker Muscular Dystrophy (DMD and BMD) are X-linked con- ditions resulting from a defect in the dystrophin gene located at Xp21.2. DMD is the most frequent neuromuscular disease in humans (1/3500 male newborns). In approximately 65% of DMD and BMD patients, deletions in the dystrophin gene have been identified as the molecular determinant. The frequency and distribution of dystrophin gene deletions in DMD/BMD patients from different populations are different. The aim of this study was to delineate various types of deleted exons and their frequency in affected male patients and identification of carrier females by linkage analysis. Materials and Methods: In this study 100 unrelated patients with DMD/BMD were stud- ied for intragenic deletions in 28 exons and the promoter region of the dystrophin gene using multiplex PCR. We also performed linkage analysis within the dystrophin gene uti- lizing 8 short tandem repeat markers. Results: Fifty-two (52%) patients showed intragenic deletions. A total of 81% of the dele- tions were located at the distal hot spot region (44-55 exons) and 19% of the deletions were located at the proximal region (exon 2-19). The most frequent deleted exons were 47(16%), 48 and 46 (11%). Most of the STR markers showed heterozygosity in the families studied. The linkage analysis was useful for detecting carrier status. Conclusion: The present study suggests that intragenic dystrophin gene deletions occur with the same frequency in Iranian patients compared with other ethnic groups.