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Duchenne and Becker muscular dystrophy
 
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Duchenne and Becker muscular dystrophy

Reviewed December 2007

What is Duchenne and Becker muscular dystrophy?

Muscular dystrophies are a group of genetic conditions characterized by progressive muscle weakness and wasting (atrophy). The Duchenne and Becker types of muscular dystrophy primarily affect the skeletal muscles, which are used for movement, and the muscles of the heart. These conditions occur much more frequently in males than in females.

Duchenne and Becker muscular dystrophies have similar signs and symptoms and are caused by different mutations in the same gene. The two conditions differ in their severity, age of onset, and rate of progression. In people with Duchenne muscular dystrophy, muscle weakness tends to appear in early childhood and progress rapidly. Affected children may have delayed motor skills, such as sitting, standing, and walking. They are usually wheelchair-dependent by adolescence. The signs and symptoms of Becker muscular dystrophy are usually milder and exhibit a large range of variation. In most cases, muscle weakness becomes apparent later in childhood or adolescence and progresses at a much slower rate.

Both the Duchenne and Becker forms of muscular dystrophy are associated with a heart condition called dilated cardiomyopathy. This form of heart disease enlarges and weakens the heart (cardiac) muscle, preventing it from pumping blood efficiently. Dilated cardiomyopathy progresses rapidly and is life-threatening in many cases. In people with Duchenne muscular dystrophy, the signs and symptoms of cardiomyopathy typically appear in adolescence. The onset of cardiomyopathy in people with Becker muscular dystrophy is later, usually in early to mid-adulthood.

How common is Duchenne and Becker muscular dystrophy?

Duchenne and Becker muscular dystrophies together affect 1 in 3,500 to 5,000 newborn males. Between 400 and 600 boys in the United States are born with these conditions each year. Females are rarely affected by these forms of muscular dystrophy.

What genes are related to Duchenne and Becker muscular dystrophy?

Mutations in the DMD gene cause Duchenne and Becker muscular dystrophy.

The DMD gene provides instructions for making a protein called dystrophin. This protein helps stabilize and protect muscle fibers and may play a role in chemical signaling within cells. Mutations in the DMD gene alter the structure or function of dystrophin, or prevent any functional dystrophin from being produced. Muscle cells without this protein become damaged as muscles repeatedly contract and relax with use. The damaged fibers weaken and die over time, leading to the muscle weakness and heart problems characteristic of Duchenne and Becker muscular dystrophies.

Read more about the DMD gene.

How do people inherit Duchenne and Becker muscular dystrophy?

This condition 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.

Where can I find information about treatment for Duchenne and Becker muscular dystrophy?

These resources address the management of Duchenne and Becker muscular dystrophy and may include treatment providers.

You might also find information on treatment of Duchenne and Becker muscular dystrophy in Educational resources and Patient support.

Where can I find additional information about Duchenne and Becker muscular dystrophy?

You may find the following resources about Duchenne and Becker muscular dystrophy helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for Duchenne and Becker muscular dystrophy?

  • DBMD
  • Duchenne/Becker muscular dystrophy
  • muscular dystrophy, Duchenne and Becker types
  • Muscular Dystrophy, Pseudohypertrophic

What if I still have specific questions about Duchenne and Becker muscular dystrophy?

Where can I find general information about genetic conditions?

What glossary definitions help with understanding Duchenne and Becker muscular dystrophy?

atrophy ; cardiac ; cardiomyopathy ; carrier ; cell ; chromosome ; dilated ; gene ; inheritance ; motor ; motor skill ; muscular dystrophy ; mutation ; new mutation ; progression ; protein ; recessive ; sex chromosomes ; sign ; skeletal muscle ; symptom ; trait ; wasting ; X-linked recessive

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

See also Understanding Medical Terminology.

References (5 links)

 

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.

 
Reviewed: December 2007
Published: May 11, 2009