Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content ++ Key Features ++ Essentials of Diagnosis ++ Progressive degeneration of skeletal and cardiac muscle occurs ++ General Considerations ++ Duchenne muscular dystrophy (DMD) Results from failure of synthesis of the muscle cytoskeletal protein dystrophin The DMD gene is located on the X chromosome, at position Xp21.1-p21.2 Approximately 1 in 4000 male children is affected Becker muscular dystrophy (BMD) A less severe phenotype than DMD Results from mutations in the same gene that result in partial expression of the dystrophin protein Evolution of the natural history of dystrophinopathies in females is demonstrating an increased incidence of serious cardiovascular disease, including cardiomyopathy and arrhythmias Large deletions or duplications can be detected in the gene for dystrophin in 65% of cases ++ Clinical Findings ++ In both DMD and BMD, progressive degeneration of skeletal and cardiac muscle occurs Boys with DMD exhibit proximal muscle weakness and pseudohypertrophy of calf muscles by age 5–6 years Patients become nonambulatory by age 13 years ++ Diagnosis ++ Serum creatine kinase levels are markedly elevated Molecular analysis has largely replaced muscle biopsy for diagnostic purposes ++ Treatment ++ Corticosteroids (prednisone/prednisolone or deflazacort) Extend independent ambulation by approximately 2.5 years Preserve respiratory strength and cardiac function into the second decade Instituting steroid treatment between 4 and 8 years, when motor function plateaus or is in decline, appears to have the greatest impact on muscle strength and cardiorespiratory function ++ Outcome ++ Prognosis ++ Boys with DMD frequently die in their twenties of respiratory failure and cardiac dysfunction Prognosis for BMD is more variable ++ Reference + +Darras BT, Miller DT, Urion DK: Dystrophinopathies. GeneReviews. www.ncbi.nlm.nih.gov/books/NBK1119/. GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of AccessPediatrics 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value AccessPediatrics Full Site: One-Year Individual Subscription $595 USD Buy Now View All Subscription Options