The Spectrum of Deletion Pattern in the Dystrophin Gene in Duchenne Muscular Dystrophy Patients: A Cross-sectional Study from Northeast India

Abstract

Introduction: Duchenne Muscular Dystrophy (DMD) is an X-linked recessive neuromuscular disorder characterised by progressive, irreversible muscle weakness. It is caused by a mutation in the dystrophin or DMD gene, leading to the absence of the essential muscle protein Dystrophin in DMD. Muscle strength continually diminishes, and death usually occurs from chronic respiratory insufficiency and/or cardiac failure. Due to the high mortality rate, early diagnosis is crucial to allow appropriate planning for patient care and treatment. In India, the traditional multiplex Polymerase Chain Reaction (PCR) assay is the most common method to detect Dystrophin gene deletion mutations. Aim: To describe the spectrum of deletion patterns in the dystrophin gene in muscular dystrophy patients attending a tertiary care hospital in Northeast India. Materials and Methods: A hospital-based cross-sectional study was conducted on a total of 53 suspected DMD patients attending the Department of Neurology and Department of Paediatrics at Assam Medical College, Dibrugarh, Assam, India from January 2016 to December 2022. Multiplex PCR was performed to study the deletion patterns for the 25 most common exons of the DMD gene for all patients at the Genetic lab, Department of Anatomy. Deletion mutations at different multiple exons were found, and the results were statistically analysed using Statistical Package for Social Sciences (SPSS) to calculate the mean and standard deviation. The results were presented in tabular form as percentages. Results: Out of the 53 cases suspected to have DMD on the basis of clinical presentation and high serum Creatine Kinase (CK) levels, 34 patients (64.2%) showing deletion mutations in the 25 most common exons of the DMD gene were included in the study. Deletions were most common in 15 (44.1%) patients in the distal hotspot region of exons 44-55. The most common gene deleted was exon 50 in 11 (32.4%) patients. The age at which symptoms were noticed was 4.7±2.01 years. The mean age at diagnosis was 8.4±2.4 years. Conclusion: In the present study, most patients suspected of DMD based on clinical and laboratory findings had deletions in the DMD gene, with the most common region for deletion in the dystrophin gene being the distal hotspot region, and exon 50 being the most commonly deleted.