Duchenne Muscular Dystrophy: Genetic and Clinical Profile in the Population of Rajasthan, India

BACKGROUND: Duchenne Muscular Dystrophy (DMD) is an X-linked recessive muscular dystrophy that affects young boys and is caused by mutation of the dystrophin gene located over X chromosome. MATERIALS AND METHODS: In this prospective study, 120 clinically diagnosed DMD patients were tested for exon deletions, duplication or point mutation. RESULTS: Of the 120 clinically suspected DMD patients, the diagnosis of DMD was confirmed by the genetic study or muscle biopsy in 116 patients. The mean age of onset was 3.2 years and the mean age at presentation was 7.2 years. 110/120 cases were confirmed by genetic testing and six were by absence of staining for dystrophin on muscle biopsy. DMD gene deletion was present in 78.5%, duplication in 5.3% and point mutation in 11.2% cases. 70.3% of patients had deletion located at a distal hot spot region. Single exon deletion was found in 16.5%. Distal hotspot exons 47, 48 and 50 were the commonly deleted exons. CONCLUSIONS: In our study, 94.8% cases showed genetic change in the DMD gene. Muscle biopsy was the choice of investigation in earlier days. Detection of DMD by DNA based method eliminates the need to do an invasive procedure for diagnosis. Hence the genetic testing should be the investigation of choice in suspected cases of DMD. The pattern of deletion, obtained in the population of Rajasthan was similar when compared with other ethnic groups of the Indian population. It would be helpful for researchers to develop drugs specific to exons or for ongoing mutation-specific therapies.