Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder caused by mutations in the DMD gene, resulting in absence or severe deficiency of the dystrophin protein, which normally provides structural support to muscle fibers. The lack of dystrophin causes progressive muscle fiber breakdown, inflammation, and replacement with fatty and fibrous tissue. Boys typically present ages 2-4 with proximal muscle weakness, causing difficulty running, climbing stairs, and rising from the floor (Gowers sign). Progressive weakness in hip, knee, and shoulder muscles follows, with children typically losing independent ambulation by age 10-12 years. Beyond muscular manifestations, the disease affects the heart (dilated cardiomyopathy) and brain (causing intellectual disability in approximately 30% of cases). Without intervention, death typically occurs in the second to third decade from respiratory failure or cardiac complications. However, recent advances in disease-modifying therapies including exon-skipping drugs (eteplirsen, golodirsen), gene therapy approaches, and supportive care have dramatically improved outcomes.