Synonyms

    * Childhood Muscular Dystrophy
    * DMD
    * Muscular Dystrophy, Classic X-linked Recessive
    * Progressive Muscular Dystrophy of Childhood
    * Pseudohypertrophic Muscular Dystrophy

General Discussion

Duchenne Muscular Dystrophy, a hereditary degenerative disease of skeletal (voluntary) muscles, is considered the most prevalent form of childhood muscular dystrophy. The disorder typically is recognized from approximately age three to six years and has a relatively rapid, progressive disease course. Duchenne Muscular Dystrophy is initially characterized by muscle weakness and wasting (atrophy) within the pelvic area that may be followed by involvement of the shoulder muscles. With disease progression, muscle weakness and atrophy affect the trunk and forearms and gradually progress to involve most major muscles of the body.

In individuals with the disorder, initial findings may include an unusual, waddling manner of walking (gait); difficulty climbing stairs or rising from a sitting position; and repeated falling. With disease progression, additional abnormalities may develop, such as progressive curvature of the spine; wasting of thigh muscles and abnormal enlargement of the calves due to degenerative changes of muscle fibers (pseudohypertrophy); and abnormal fixation of certain joints (joint contractures) due to muscle weakness, prolonged immobility, and shortening of muscle fibers. By approximately age 10 to 12, most affected individuals require the use of a wheelchair.

Duchenne Muscular Dystrophy is also typically characterized by additional abnormalities, including involvement of heart muscle (cardiomyopathy) and varying degrees of intellectual impairment. Affected individuals may develop an increased susceptibility to respiratory infections (e.g., pneumonia), respiratory failure, impaired ability of the heart to pump blood effectively (heart failure), or other serious findings, leading to potentially life-threatening complications by late adolescence or early adulthood.

Duchenne Muscular Dystrophy is caused by changes (mutations) of a gene on the short arm (p) of chromosome X (Xp21.2). The gene regulates the production of a protein that is found in skeletal and cardiac muscle. Known as dystrophin, the protein is thought to play an important role in maintaining the structure of these muscle cells.

In most affected individuals, Duchenne Muscular Dystrophy is inherited as an X-linked recessive trait. Therefore, the disorder is usually fully expressed in males only. However, in rare instances, females who carry a copy of the mutated gene (heterozygous carriers) may develop certain, typically milder symptoms associated with the disorder. In addition, for some individuals with Duchenne Muscular Dystrophy, there is no family history of the disease. In such cases, the disorder may be caused by new (sporadic) genetic mutations that occur for unknown reasons.