Becker muscular dystrophy

Synonyms

1

Overview

Becker muscular dystrophy is an X-linked recessive inherited disorder characterized by slowly progressive muscle weakness of the legs and pelvis. It is a type of dystrophinopathy, which includes a spectrum of muscle diseases in which there is insufficient dystrophin produced in the muscle cells, resulting in instability in the structure of muscle cell membrane.

Symptoms

  • Muscle weakness, slowly progressive, causing difficulty with muscle skills (running, hopping, jumping)
  • Progressive difficulty walking + Ability to walk may continue into adulthood (up to age 40) + Frequent falls
  • problems breathing
  • Cognitive dysfunction
  • Skeletal deformities, chest and back (scoliosis)
  • Muscle deformities and contractures of heels, legs Pseudohypertrophy of calf

Causes

Inherited diseases involving a defective gene. Each form of muscular dystrophy is caused by a genetic mutation that's particular to that type of the disease. The most common types of muscular dystrophy appear to be due to a genetic deficiency of the muscle protein dystrophin.

Duchenne's and Becker muscular dystrophies are passed from mother to son through one of the mother's genes in a pattern called X-linked recessive inheritance. Boys inherit an X chromosome from their mothers and a Y chromosome from their fathers. The X-Y combination makes them male. Girls inherit two X chromosomes, one from their mothers and one from their fathers. The X-X combination determines that they are female.

Prevention

Genetic counseling may be advised if there is a family history of Becker muscular dystrophy.

Diagnosis

The health care provider will do a nervous system (neurological) and muscle examination. A careful medical history is also important, because the pattern of symptom development resembles that of Duchenne muscular dystrophy. However, Becker muscular dystrophy gets worse much more slowly.

Tests include:

  • CPK
  • Electromyography (EMG)
  • Muscle biopsy or genetic test (blood test)

Prognosis

Becker muscular dystrophy results in slowly progressive disability. Death may occur in the 50s or 60s, but patients can live to an advanced age.

Treatment

There is no known cure for Becker muscular dystrophy. Treatment is aimed at control of symptoms to maximize the quality of life. Some doctors prescribe steroids to help keep a patient walking for as long as possible. Activity is encouraged. Inactivity (such 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.

Resources

Call your health care provider if:

  • Symptoms of Becker muscular dystrophy appear
  • A person with Becker muscular dystrophy develops new symptoms (particularly fever with cough or breathing difficulties)
  • You are planning to start a family and you or other family members have been diagnosed with Becker muscular dystrophy