Introduction
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.
Epidemiology
- 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+ |
Pathophysiology
Genetics
- 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
Features
- develops after the age of 10 years
- intellectual impairment much less common than in Duchenne