Becker muscular dystrophy
Other Names for this Disease
- Becker's muscular dystrophy
- Benign pseudohypertrophic muscular dystrophy
- Muscular dystrophy pseudohypertrophic progressive, Becker type
- Muscular dystrophy, Becker type
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Questions on this page
- What is Becker muscular dystrophy?
- What are the symptoms of Becker muscular dystrophy?
- What causes Becker muscular dystrophy?
- How do people inherit Becker muscular dystrophy?
- How is Becker muscular dystrophy diagnosed?
- How might Becker muscular dystrophy be treated?
- What is the prognosis for individuals with Becker muscular dystrophy?
Becker muscular dystrophy is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation must be present in both copies of the gene to cause the disorder. Males are affected by X-linked recessive disorders much more frequently than females. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
In about two thirds of cases, an affected male inherits the mutation from a mother who carries an altered copy of the DMD gene. The other one third of cases probably result from new mutations in the gene.
In X-linked recessive inheritance, a female with one mutated copy of the gene in each cell is called a carrier. She can pass on the altered gene, but usually does not experience signs and symptoms of the disorder. Occasionally, however, females who carry a DMD mutation may have muscle weakness and cramping. These symptoms are typically milder than the severe muscle weakness and atrophy seen in affected males. Females who carry a DMD mutation also have an increased risk of developing heart abnormalities including dilated cardiomyopathy.
An exam may find:
- Abnormally developed bones, leading to deformities of the chest and back (scoliosis)
- Abnormality of heart muscle function (cardiomyopathy)
- Congestive heart failure or irregular heartbeat (arrhythmias)
- Muscle deformities
- Contractures of heels and legs
- Fat and connective tissue (pseudohypertrophy) in calf muscles
- Muscle wasting that begins in the legs and pelvis, then progresses to the muscles of the shoulders, neck, arms, and respiratory system
There is no known cure for Becker muscular dystrophy. Treatment is aimed at controlling symptoms to maximize quality of life. Individuals with Becker muscular dystrophy are encouraged to remain active, as bed rest can worsen the muscle disease. Physical therapy may be helpful to maintain muscle strength. Orthopedic appliances such as braces and wheelchairs may improve mobility and self-care.
- Kaneshiro NK, Hoch DB. Becker's muscular dystrophy. MedlinePlus. 2008; http://www.nlm.nih.gov/medlineplus/ency/article/000706.htm. Accessed 11/18/2009.
- Duchenne and Becker muscular dystrophy. Genetics Home Reference (GHR). 2007; http://www.ghr.nlm.nih.gov/condition=duchenneandbeckermusculardystrophy. Accessed 11/18/2009.
- Muscular Dystrophy, Becker. National Organization for Rare Disorders (NORD). 2007; http://www.rarediseases.org/search/rdbdetail_abstract.html?disname=Muscular%20Dystrophy%2C%20Becker. Accessed 11/18/2009.