Duchenne and Becker muscular dystrophy

Overview & Definition

A boy who cannot run as fast as his friends, who walks on his toes and cannot jump, may carry a single gene that slowly unmakes his muscle. Duchenne muscular dystrophy is the most common and the most severe inherited muscular dystrophy of childhood, an X-linked recessive disorder in which loss-of-function mutations in the DMD gene abolish the sarcolemmal protein dystrophin. The muscle fibre loses its mechanical anchor, tears itself apart with every contraction, and is replaced by fat and scar. The boy walks later than his peers, weakens through early childhood, loses the ability to walk in the first decade, and dies of the heart and the lungs unless the disease is modified. [4]

Becker muscular dystrophy is the allelic and milder partner, born of the same gene but of mutations that leave a shortened, partly functional dystrophin rather than none at all. The two are dystrophinopathies, and they sit on a continuous spectrum of severity that tracks with how much dystrophin survives. The Becker boy walks into adulthood, and his heart, not his legs, may be the organ that threatens him first. [11]

Three ideas make this topic central to the paediatric exam. The first is recognition, because the boy is often labelled clumsy or lazy for years before someone measures a creatine kinase that is off the scale. The second is the glucocorticoid backbone, because prednisolone or deflazacort, started at the right time, changes the trajectory of the disease. The third is the systems care, because the heart and the lungs now decide the outcome, and a boy who is watched and treated can live into his fourth decade. The modern care considerations of Birnkrant and colleagues, building on the Bushby guidelines, set these principles out and remain the single most testable source. [4][5][6]

References11Show ledgerHide ledger

1. [1]Hoffman EP, Brown RH Jr, Kunkel LM Dystrophin: the protein product of the Duchenne muscular dystrophy locus. Cell, 1987.PMID 3319190
2. [2]Koenig M, Beggs AH, Moyer M The molecular basis for Duchenne versus Becker muscular dystrophy: correlation of severity with type of deletion. Am J Hum Genet, 1989.PMID 2491009
3. [3]Bushby K, Finkel R, Birnkrant DJ Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and pharmacological and psychosocial management. Lancet Neurol, 2010.PMID 19945913
4. [4]Birnkrant DJ, Bushby K, Bann CM Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and neuromuscular, rehabilitation, endocrine, and gastrointestinal and nutritional management. Lancet Neurol, 2018.PMID 29395989
5. [5]Birnkrant DJ, Bushby K, Bann CM Diagnosis and management of Duchenne muscular dystrophy, part 2: respiratory, cardiac, bone health, and orthopaedic management. Lancet Neurol, 2018.PMID 29395990
6. [6]Birnkrant DJ, Bushby K, Bann CM Diagnosis and management of Duchenne muscular dystrophy, part 3: primary care, emergency management, psychosocial care, and transitions of care across the lifespan. Lancet Neurol, 2018.PMID 29398641
7. [7]Griggs RC, Miller JP, Greenberg CR Efficacy and safety of deflazacort vs prednisone and placebo for Duchenne muscular dystrophy. Neurology, 2016.PMID 27566742
8. [8]Mendell JR, Rodino-Klapac LR, Sahenk Z Eteplirsen for the treatment of Duchenne muscular dystrophy. Ann Neurol, 2013.PMID 23907995
9. [9]Raman SV, Hor KN, Mazur W Eplerenone for early cardiomyopathy in Duchenne muscular dystrophy: a randomised, double-blind, placebo-controlled trial. Lancet Neurol, 2015.PMID 25554404
10. [10]Mendell JR, Muntoni F, McDonald CM AAV gene therapy for Duchenne muscular dystrophy: the EMBARK phase 3 randomized trial. Nat Med, 2025.PMID 39385046
11. [11]Emery AE, Skinner R Clinical studies in benign (Becker type) X-linked muscular dystrophy. Clin Genet, 1976.PMID 975594