Duchenne muscular dystrophy is an X-linked recessive disorder caused by a mutation in the dystrophin gene located on the X chromosome. The mutation leads to absent dystrophin protein, which is important in muscle cell structural stability. Males are affected, although a minority of female carriers are affected.

Symptoms are detected in infancy or early childhood and include progressive proximal muscle weakness and atrophy of the legs and pelvis, which often leads to difficulty walking or climbing stairs, pseudohypertrophy of the calves, enlarged tongue, fatigue, and behavioral or learning disorders. Later, there can be arm and neck weakness, scoliosis, contractures, cardiomyopathy, dysphagia, and respiratory failure. Most patients are wheelchair dependent by age 12, and the average age of death is 25.