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Genetic and Rare Diseases Information Center (GARD)

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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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Your Question

I am a physician who frequently sees patients with Becker muscular dystrophy. Can you provide me with patient-friendly information about this condition?

Our Answer

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What is Becker muscular dystrophy?

Becker muscular dystrophy (BMD) is an inherited condition that primarily affects males and causes progressive weakness and wasting of the skeletal and cardiac (heart) muscles.[1][2] The age of onset and rate of progression can vary among affected people. Muscle weakness usually becomes apparent between the ages of 5 and 15. In some cases, heart involvement (cardiomyopathy) is the first sign.[2] BMD is caused by a mutation in the DMD gene and is inherited in an X-linked recessive manner. BMD is very similar to Duchenne muscular dystrophy, except that symptoms begin later and progress at a slower rate.[1] There is no cure for this condition, and treatment aims to relieve symptoms to help quality of life.[3] People with BMD may survive into their 40s or beyond.[1]
Last updated: 3/5/2014

What are the signs and symptoms of Becker muscular dystrophy?

The symptoms of Becker muscular dystrophy (BMD) may begin anywhere from childhood to a person's early 20s.[4][5] Muscle weakness often affects the legs and pelvis, and slowly gets worse.[4] Over time, affected people begin to have difficulty walking, frequent falls, difficulty with muscle skills (such as running, hopping, and jumping), and loss of muscle mass.[3] Eventually, affected people require a wheelchair.[5] The condition also affects the heart muscles, causing dilated cardiomyopathy. This form of heart disease enlarges and weakens the heart muscle, preventing it from pumping blood efficiently. Dilated cardiomyopathy progresses rapidly and is life-threatening in many cases.[4] Other symptoms of BMD may include cognitive problems, fatigue, loss of balance and coordination, problems breathing, and muscle weakness in the arms, neck and other areas.[3]
Last updated: 3/5/2014

What causes Becker muscular dystrophy?

Becker muscular dystrophy (BMD) is caused by specific mutations in the DMD gene. The DMD gene gives 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 that lead to an abnormal "version" of dystrophin that keeps some of its function usually cause BMD. Muscle cells without fully functional dystrophin become damaged as muscles contract and relax with use. They then weaken and die over time, leading to the muscle weakness and heart problems in people with BMD.[4]
Last updated: 3/5/2014

How is Becker muscular dystrophy inherited?

Becker muscular dystrophy is inherited in an X-linked recessive manner. A condition is considered X-linked if the mutated gene that causes the condition is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one mutated 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 condition. Males are affected by X-linked recessive disorders much more frequently than females. A specific characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.[4]

In X-linked recessive inheritance, a female with one mutated copy of the gene in each cell is called a carrier. Female carriers of X-linked recessive conditions have a 50% (1 in 2) risk to pass on the mutated gene to each child. Male children have a 50% risk to be affected, and female children have a 50% risk to be a carrier. Female carriers usually do not have signs or symptoms of the condition. Occasionally, females who carry a DMD mutation may have muscle weakness and cramping. These symptoms are typically milder than the severe muscle weakness and wasting in affected males. Females who carry a DMD mutation also have an increased risk to develop heart problems, including dilated cardiomyopathy.[4]

In about two thirds of cases, an affected male inherits the mutation from his mother who carries a mutated copy of the DMD gene. The other third of cases probably result from new mutations in the gene.[4]

Last updated: 3/5/2014

How is Becker muscular dystrophy diagnosed?

A healthcare provider will conduct a neurological and muscle examination. A careful medical history is also important to differentiate between Becker and Duchenne muscular dystrophy.[3]

An exam may find:[3]

  • 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

Tests include:[3]

Last updated: 11/18/2009

How might Becker muscular dystrophy be treated?

There is currently no cure for Becker muscular dystrophy (BMD), and management aims to help with symptoms and improve the quality of life. Affected people are encouraged to remain active, because inactivity (such as bed rest) can make the muscle disease worse.[3]

Physical therapy can help with stretching tight muscles and using assistive devices; occupational therapy can help with daily living skills; and speech therapy may help those with dysphagia (difficulty swallowing). Surgery may be needed for progressive scoliosis and development of contractures.[6]

People with BMD should be monitored for orthopedic complications. Cardiac (heart) evaluations are recommended beginning at around 10 years old, or when symptoms first begin. Evaluations should be repeated at least every two years.[7]

Some studies have shown that certain corticosteroids (such as prednisone or prednisolone) can slow the decline of muscle strength in people with Duchenne muscular dystophy; however, information about their use in people with BMD is limited.[7] There are a number of additional therapies for BMD being studied.[7] Potential future treatments for BMD may involve gene therapy, myoblast treatment, and/or the use of stem cells.[6]
Last updated: 3/5/2014

What is the long-term outlook for people with Becker muscular dystrophy?

Becker muscular dystrophy generally leads to slowly worsening disability, but the amount of disability can vary among affected people. Some men need a wheelchair, while others may only need walking aids such as canes or braces. The lifespan is often shorted due to heart disease and respiratory complications.[8] Most people with BMD survive well into mid- to late adulthood. If the effects of the condition on the heart are mild, or if they are adequately controlled with medical intervention, a person can have a normal or nearly normal life span.[9]
Last updated: 3/5/2014