Aspire Educational Series: Becker Muscular Dystrophy (BMD)- Part 15

Becker muscular dystrophy (BMD) is a neuromuscular disease characterized by progressive muscle wasting and weakness due to degeneration of skeletal, smooth and cardiac muscle. This form of muscular dystrophy is named after the German doctor Peter Emil Becker who described the condition in 1955.  Becker muscular dystrophy follows x-linked recessive inheritance so it mostly affects males, but some females are affected. The clinical picture is similar to that of Duchenne muscular dystrophy (DMD). BMD is generally milder than DMD, and the onset of symptoms usually occurs later – teens or early twenties and symptoms vary greatly between affected individuals.

BMD is caused by a defect in the dystrophin gene located on the X-chromosome. The faulty gene results in a deficiency of the protein dystrophin, causing muscles to deteriorate and break down in males. While females have two copies of the X-chromosome, a defect in one can nearly always produce enough dystrophin to have normal muscle function making her a carrier. Males, however, have only one X-chromosome and therefore one dystrophin gene copy. So, a faulty dystrophin gene results in DMD or BMD.

The incidence and prevalence of BMD are lower than those of DMD. The estimated incidence of BMD is 1 individual per 30,000 male births, compared with 1 individual per 3500 male births for DMD.  The prevalence of BMD is 17-27 cases per 1 million population.

Symptoms include muscle weakness of the lower body, including the legs and pelvis area, slowly gets worse, causing:

Other symptoms may include:

Muscles lose their elasticity, leading to tightness (contractures) around joints, and difficulty with stretching leg and heel muscles. Contractures can lead to skeletal deformities such as scoliosis or a curved spine. Due to the weakening of the heart muscle, people with BMD have a high risk of developing heart disease (cardiomyopathy). Many patients die, due to complications, in their mid-to-late 20s. Less than half of those with Becker MD survive to 40 years of age. Those that do are typically severely disabled.

Once BMD is suspected, diagnostic tests will be offered to establish a definite diagnosis. These may include:

No specific treatment is available for Becker muscular dystrophy but the quality of life and lifespan can be improved with appropriate care. Physical and occupational therapy can reduce or delay joint contractures. Surgery is sometimes recommended to treat contractures or scoliosis. Weight control can help to reduce stress on the heart and muscles. Corticosteroids are often prescribed to help slow down the loss of muscle function. Routine monitoring by a cardiologist is recommended.



 

 

References

  1. Becker Muscular Dystrophy (BMD). MDA – Muscular Dystrophy Association. www.mda.org/disease/becker-muscular-dystrophy Retrieved on 28-03-2017.
  2. Becker muscular dystrophy. Medline Plus. www.medlineplus.gov/ency/article/000706.htm  Retrieved on 28-03-2017.
  3. Becker muscular dystrophy. Medscape. www.emedicine.medscape.com/article/313417-overview#a6  Retrieved on 28-03-2017.
  4. Muscular Dystrophy, Becker. NORD – National Organization for Rare Disorders. www.rarediseases.org/rare-diseases/muscular-dystrophy-becker/  Retrieved on 28-03-2017.
  5. Becker Muscular Dystrophy. Muscular Dystrophy Canada. www.muscle.ca/wp-content/uploads/2012/11/Becker_E.pdf. Retrieved on 28-03-2017.
  6. Becker Muscular Dystrophy. AANEM – American Association of Neuromuscular and Electrodiagnostic Medicine. www.aanem.org/Patients/Disorders/Becker-Muscular-Dystrophy. Retrieved on 28-03-2017.
  7. What is Becker muscular dystrophy? DuchenneConnect. www.duchenneconnect.org/about-dmd-bmd.html  Retrieved on 28-03-2017.
  8. Becker Muscular Dystrophy. Nationwide Children’s. www.nationwidechildrens.org/becker-muscular-dystrophy.com. Retrieved on 28-03-2017.