X-Linked Dystrophinopathies

Dystrophin is part of a protein complex that links the cytoskeleton with membrane proteins. Though there are exceptions, Duchenne muscular dystrophy is usually caused by mutations that prevent dystrophin expression and Becker muscular dystrophy is usually caused by mutations that result in reduced amounts of protein or structurally abnormal protein.

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Because the dystrophin gene is located on the X chromosome, Duchenne is an X-linked condition and is most often diagnosed in males. In rare cases, females can have the Duchenne phenotype, but are usually protected from manifesting skeletal muscle involvement by their second copy of the dystrophin gene. All female carriers should be monitored for cardiomyopathy. For more information, see the section on “Carriers and Potential Carriers.”