Natural history of a cohort of Duchenne muscular dystrophy children seen between 1998 and 2014: An observational study from South India.

BACKGROUND: Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy. There are no large studies describing its natural course from India. MATERIALS AND METHODS: Immunohistochemically/genetically confirmed DMD patients diagnosed between 1998 and 2014 were ambispectively included. The main aim was to study the natural course of motor milestones, i.e., age at onset of wheelchair status, bedbound state, and age at death, which were considered as primary outcome measures. We also correlated the DMD genotype with the motor milestones and other phenotypic features. RESULTS: A total of 500 DMD patients were included and 275 participated in the study. The mean age at symptom onset was 3.7 ± 1.9 years, mean age at presentation was 8.1 ± 2.5 years, and mean duration of illness was 4.4 ± 2.6 years. On following them over 15 years, 155 (56.4%) had attained at least one of the primary outcome measures. Wheelchair status was attained in 124 (45.1%) [mean age: 10.4 ± 1.6 years] and bedbound state in 24 (8.7%; mean age: 11.8 ± 2.2 years) patients. Seven patients (2.6%) died during the follow-up period (mean age: 15.2 ± 2.4 years). There was no significant impact of the genotypic or phenotypic features on the primary outcome. CONCLUSION: The pattern of major motor milestones (primary outcome measures) in this large cohort is comparable with that of the Western population despite variability in medical care. The genotypic pattern was also similar to other large studies, which suggests that DMD is a more homogeneous disorder with limited ethnic variability in its geno-phenotypic expression.