There are more than 30 types of muscular dystrophy (MD), a group of diseases in which a defective gene causes weakness and degeneration of skeletal muscles. MD can strike at any age, can progress slowly or quickly, and can vary in severity from mildly disabling to fatal.

The most common form of muscular dystrophy, Duchenne MD, is caused by a deficiency of dystrophin, a protein that helps maintain muscle. This version strikes mainly boys between the ages of 3 and 5 and progresses rapidly. Most victims can’t walk by age 12 and later need a respirator to breathe. Early warning signs in children include frequent falls, large calf muscles, difficulty running and jumping, and a tendency to walk on the toes or balls of the feet. A less severe form of MD is called Becker MD. Both disorders are passed from mother to son by way of a defective gene on the X chromosome, which a boy inherits from his mother. Girls get another X from their fathers, which protects them from the disease.

Other forms include facioscapulohumeral MD, which begins in the teenage years and causes weakness of the face, arm, and leg muscles; and myotonic MD, the disorder’s most common adult form, characterized by cataracts, heart problems, prolonged muscle spasms, and gaunt facial features.

Symptoms of MD include muscle weakness, an apparent lack of coordination, and progressive crippling as muscles around the joints become stiff and lose mobility. In the late stages of MD, fat and connective tissues completely replace muscle fibers.

MD can be diagnosed with a blood test for creatine kinase, an enzyme released by damaged muscles. Electrical impulse tests, ultrasound, and muscle biopsy may also be used to test for damage and confirm the diagnosis.

There is no way to stop or reverse MD, but physical therapy and orthopedic appliances can make living with MD less debilitating. Doctors can perform corrective surgery to relieve joint pain, and they may prescribe drugs such as corticosteroids, anticonvulsants, immunosuppressants, and antibiotics to delay cell damage and fight infection. Braces can provide support for weakened muscles, although canes, walkers, or wheelchairs may be necessary in advanced cases.

ADDITIONAL FACTS

  1. Because respiratory infections may become a problem in later stages of MD, patients should be vaccinated against pneumonia and get a flu shot every year.
  2. The Duchenne and Becker forms of MD rarely occur in women—but women who have one X chromosome with the defective gene for these disorders are carriers and sometimes develop heart muscle problems and mild muscle weakness.
  3. The first Muscular Dystrophy Association Labor Day Telethon—now an annual event hosted by Jerry Lewis (1926–) and benefiting “Jerry’s Kids”—was broadcast in 1966. It was the first televised fund-raising event of its kind to raise more than $1 million.