dmd

Duchenne muscular dystrophy (DMD) is a severe inherited neuromuscular disorder caused by mutations in the DMD gene, which encodes dystrophin, a protein that helps stabilize muscle fibers during contraction. In the absence of functional dystrophin, muscle fibers are damaged over time, leading to progressive weakness and wasting that primarily affects the proximal muscles of the hips, thighs, and shoulders.

DMD typically presents in early childhood with delays in motor milestones, frequent falls, difficulty climbing stairs, and a characteristic evolving pattern of weakness. Gowers' sign, where a child uses the hands to push off the thighs to stand, and calf pseudohypertrophy are common. Most boys lose the ability to walk in their early teens, and progressive respiratory and cardiac problems become major concerns. Female carriers may have milder symptoms or late-onset cardiomyopathy.

Genetically, DMD is inherited in an X-linked recessive manner. Mutations in the DMD gene can include large deletions, duplications, or point mutations that disrupt dystrophin production. The DMD gene is one of the largest in the human genome, contributing to a high rate of mutational events. Dystrophin links the cytoskeleton of muscle fibers to the surrounding extracellular matrix, protecting the membrane during muscle activity; its absence leads to membrane fragility and degeneration.

Diagnosis is based on clinical features, elevated serum creatine kinase in early disease, and confirmatory genetic testing identifying a DMD gene mutation. Muscle biopsy showing little or no dystrophin used to be common but is now less often required.

Management is multidisciplinary, including physical therapy, orthopedic care, respiratory support, and cardiac monitoring. Corticosteroids can slow progression and preserve strength. Emerging exon-skipping therapies and other gene-based approaches are under development, aiming to restore dystrophin production and modify disease trajectory. With comprehensive care, life expectancy has improved, though DMD remains a life-limiting condition.