Muscular Dystrophy - Description

The nine different forms of muscular dystrophy are usually distinguished by the part of the body they affect. They include the following:

• Duchenne muscular dystrophy (DMD). DMD primarily affects young boys. It causes weakness in the muscles that gets worse over time. The problem usually begins in the legs and then spreads to muscles in other parts of the body. It is the severest form of MD. DMD occurs in about 1 out of every 3,500 male births. About 8,000 boys and young men in the United States have the disorder. A milder form of the disorder occurs in a very few females.
• Becker muscular dystrophy (BMD). BMD affects older boys and young men. It is a milder form of MD than DMD, which occurs in about 1 in every 30,000 male births.
• Emery-Dreifuss muscular dystrophy (EDMD). EDMD is a very rare form of MD. It affects young boys exclusively. It causes contracture (permanent tightening) and weakness of the calf muscles and weakness in the shoulders and upper arms. It can also cause problems in the electrical signals that cause the heart to beat. Fewer than 300 cases of EDMD have been seen.
• Limb-girdle muscular dystrophy (LGMD). LGMD begins in later childhood or early adulthood. It affects both men and women. It causes weakness in the muscles around the hips and shoulders. LGMD has the greatest variety of symptoms of all forms of MD. In fact, researchers think it may actually consist of other forms of the disorder. Diagnosis of LGMD is difficult, and some patients with the disorder may have been diagnosed incorrectly in the past. The number of people with LGMD in the United States is probably a few thousand.
• Facioscapulohumeral muscular dystrophy (FSH). (pronounced FAY-shee-o-SKAP-yuh-lo-HYOOM-uh-ruhl) is also known as Landouzy-Dejerine disease. It begins in later childhood or early adulthood. It affects both men and women. FSH is characterized by weakness in the muscles of the face, shoulders, and upper arms. The hips and legs may also be affected. FSH occurs in about 1 out of every 2,000 people. About 13,000 people in the United States have the condition.
• Myotonic dystrophy. Myotonic (pronounced my-uh-TON-ik) dystrophy is also known as Steinert's disease. It affects both men and women. The disorder is usually seen first in the face, feet, and hands. It is characterized by an inability to relax the affected muscles. This condition is known as myotonia (pronounced my-uh-TO-nee-uh). Symptoms may first appear at any time between birth and adulthood. It is the most common form of MD. About 30,000 people in the United States have myotonic dystrophy.
• Oculopharyngeal muscular dystrophy (OPMD). Oculopharyngeal (pronounced OK-yuh-lo-fuh-RIN-jee-uhl) muscular dystrophy OPMD causes weakness in the eye muscles and throat. It affects adults of both sexes. It is most common among French Canadian families in Quebec and in Spanish American families in the southwestern United States.
• Distal muscular dystrophy (DD). DD begins in middle age or later. It causes weakness in the muscles of the feet and hands. It is most common in Sweden and rare in other parts of the world.
• Congenital muscular dystrophy (CMD). CMD appears at birth and progresses slowly thereafter. It causes a generalized weakness in muscles throughout the body. One form of the disorder is called Fukuyama, for a district in Japan where it is relatively common. Fukuyama CMD also causes mental retardation.