Scoliosis in patients with Duchenne muscular dystrophy.

espite recent research developments, Duchenne muscular dystrophy remains a fatal neuromuscular disease, affecting two to three boys in 10,000. It is an inherited X-linked recessive condition caused by a frameshift mutation in the dystrophin gene at the Xp21.2 locus of the X chromosome. Dystrophin is a large cell-membrane protein involved in calcium transport in the muscle cell. Boys with Duchenne muscular dystrophy have an absolute absence of dystrophin, leading to deterioration of the muscle cells and replacement with fibrofatty tissue. This is in contrast to Becker muscular dystrophy, in which less disruptive mutations that do not result in a frame shift lead to production of variable amounts of a smaller, genetically abnormal dystrophin protein. Duchenne muscular dystrophy is highly suspected in boys who have a markedly elevated serum creatine phosphokinase level; in two-thirds of such patients, the diagnosis can be confirmed by genetic testing. Approximately two-thirds of affected patients have large deletions or duplications that can be detected with use of the multiplex polymerase chain reaction and Southern blot techniques. Detection of point mutations in the remaining one-third of patients is more difficult. In patients without detectable mutations, muscle biopsy with dystrophin analysis is necessary for diagnosis. Staining of muscle biopsy specimens with antidystrophin antibodies in patients with Duchenne muscular dystrophy reveals a complete lack of staining of sarcolemma, whereas specimens from patients with Becker muscular dystrophy do have enough dystrophin present so that partial staining of the sarcolemma is seen. The clinical course of weakness in patients with Duchenne muscular dystrophy is one of relentless progression. Death from pulmonary or cardiac compromise occurs in the second or third decade of life.