Becker muscular dystrophy is an x-linked recessive dystrophinopathy. In very simple terms it is often thought of as a 'less severe' version of Duchenne muscular dystrophy.


  • Incidence: 0.04 cases per 100,000 person-years
  • Peak incidence: 20-30 years
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+


  • due to mutation in the gene encoding dystrophin, dystrophin gene on Xp21
  • dystrophin is part of a large membrane associated protein in muscle which connects the muscle membrane to actin, part of the muscle cytoskeleton
  • in Duchenne muscular dystrophy there is a frameshift mutation resulting in one or both of the binding sites are lost leading to a severe form
  • in Becker muscular dystrophy there is a non-frameshift insertion in the dystrophin gene resulting in both binding sites being preserved leading to a milder form

Clinical features

  • develops after the age of 10 years
  • intellectual impairment much less common than in Duchenne