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Becker muscular dystrophy
Other Resources UpToDate PubMed

Becker muscular dystrophy

Contributors: Jamie Adams MD, Richard L. Barbano MD, PhD
Other Resources UpToDate PubMed


Becker muscular dystrophy (BMD) is an X-linked recessive disorder caused by a mutation in the dystrophin gene located on the X chromosome. The mutation leads to reduced dystrophin protein, which is important in muscle cell structural stability. Males are affected, although females can be carriers. The incidence is about 1 in 30 000 male infants.

BMD is similar to Duchenne muscular dystrophy (DMD) but typically has a later onset, around age 10 or older, and a milder course. Symptoms include progressive proximal muscle weakness and atrophy of the legs and pelvis, which often leads to difficulty walking or climbing stairs, myalgias with exertion, pseudohypertrophy of the calves, and fatigue. Cognition is often normal. Neck flexion strength is typically preserved, and contractures are not as common or severe as in DMD. However, cardiac disease (cardiomyopathy) is often more apparent and a more common cause of death than in DMD. Later in the course of disease, there can be arm weakness, scoliosis, dysphagia, and respiratory failure. Prognosis is variable, but patients typically remain ambulatory until age 16 or older and usually survive past age 30.


G71.01 – Duchenne or Becker muscular dystrophy

387732009 – Becker muscular dystrophy

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Duchenne muscular dystrophy
  • Limb-girdle muscular dystrophy
  • Facioscapulohumeral dystrophy
  • Emery-Dreifuss muscular dystrophy
  • Myotonic muscular dystrophy
  • Congenital muscular dystrophy
  • Distal muscular dystrophy (eg, Miyoshi myopathy)
  • Congenital, metabolic, or Drug-induced myopathies
  • Glycogen storage disease type 2 (Pompe disease)
  • Spinal muscular atrophy
  • Myasthenia gravis – look for fluctuations in symptoms
  • Lambert-Eaton myasthenic syndrome
  • Dermatomyositis
  • Polymyositis
  • Spinal cord tumors
  • Tethered cord – look for bladder symptoms

Best Tests

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Management Pearls

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Last Reviewed:08/26/2017
Last Updated:10/11/2022
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Becker muscular dystrophy
Copyright © 2024 VisualDx®. All rights reserved.