Introduction
Questions and Answers
Part I
Part II
Characteristics of the 9 Muscular Dystrophies
MDA's Search for Causes
MDA's Search for Treatments and Cures
MDA is Ready to Help
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MOST FREQUENTLY ASKED QUESTIONS ABOUT MUSCULAR DYSTROPHY
Part I
 What is muscular dystrophy?
The word dystrophy comes from Latin and Greek roots meaning "faulty nutrition." When doctors first began describing muscle diseases in the 19th century, they had few tools other than their own eyes. Muscles in many diseases appeared to be wasting away, and the doctors theorized that they somehow weren't being properly nourished.
Today, we know that many muscle-wasting diseases are caused by defects in genes for muscle proteins. Most of these proteins appear to play a role in supporting the structure of muscle fibers, although some may play a role in the biochemical processes that go on in muscle fibers. The term muscular dystrophy refers to a group of genetic diseases marked by progressive weakness and degeneration of the skeletal, or voluntary, muscles, which control movement. The muscles of the heart and some other involuntary muscles are also affected in some forms of muscular dystrophy, and a few forms involve other organs as well.
Does muscular dystrophy affect children exclusively?
No. Muscular dystrophy can affect people of all ages. While some forms first become apparent in infancy or childhood, others may not appear until middle age or later. With improved medical care, particularly of problems affecting the heart and lungs, children with muscular dystrophy are living further into adulthood than ever before.
What are the forms of muscular dystrophy?
The major forms of muscular dystrophy are myotonic, Duchenne, Becker, limb-girdle, facioscapulohumeral, congenital, oculopharyngeal, distal and Emery-Dreifuss.
Some of these names are based on the locations of affected muscles. For example, "facioscapulohumeral" refers to the muscles that move the face, scapula (shoulder blade) and humerus (upper arm bone). Others are based on the type of muscle problem involved ("myotonic" means difficulty relaxing muscles), the age of onset of the disease (as in "congenital," or birth-onset, dystrophy), or the doctors who first described the disease (Duchenne, Becker, Emery and Dreifuss are doctors' names).
As the root causes (gene defects) of the muscular dystrophies are discovered, doctors are beginning to change their thinking about how to classify some of the dystrophies. In some cases, a type of muscular dystrophy that looked like it might be one disease has been found to be several different diseases, caused by several different gene defects. This is true for limb-girdle, congenital and distal dystrophies. In other cases, diseases that looked different have been found to be one disease with variations in severity. This is the case with Duchenne and Becker dystrophies.
How do the forms of muscular dystrophy differ?
They differ in severity, age of onset, muscles first and most often affected, the rate at which symptoms progress, and the way the disorders are inherited.
What causes muscular dystrophy?
Flaws in muscle protein genes cause muscular dystrophies. Each cell in our bodies contains tens of thousands of genes. Each gene is a string of the chemical DNA and is the "code" for a protein. (Another way to think of a gene is that it's the "instructions" or "recipe" for a protein.) If the recipe for a protein is wrong, the protein is made wrong or in the wrong amount or sometimes not at all.
Are muscular dystrophies always inherited?
Muscular dystrophies are generally inherited but in some cases no family history of the disease may exist.
Is muscular dystrophy contagious?
No. Genetic diseases aren't contagious.
Is a family medical history important?
Yes. Because the muscular dystrophies can be inherited, it's important for the doctor to know if anyone in the family ever had a similar disorder.
How is muscular dystrophy diagnosed?
A doctor makes a diagnosis by evaluating the patient's medical history and by performing a thorough physical examination. Essential to diagnosis are details about when weakness first appeared, its severity, and which muscles are affected. Diagnostic tests may also be used to help the doctor distinguish between different forms of muscular dystrophy, or between muscular dystrophy and other disorders of muscle or nerve.
What are some common diagnostic tests?
Studying a small piece of muscle tissue taken from an individual during a muscle biopsy can sometimes tell a physician whether a disorder is muscular dystrophy and which form of the disease it is.
In Duchenne and Becker muscular dystrophy, a muscle protein called dystrophin is either missing, deficient or abnormally formed. This protein can be examined in the muscle sample.
The reason for the flawed or deficient muscle protein is a flawed gene for dystrophin. A test that involves looking at this gene -- DNA testing -- can be done to diagnose or rule out Duchenne or Becker muscular dystrophies.
Another diagnostic test is the electromyogram (EMG). To do this test, small electrodes are put into the muscle, which allows the doctor to measure the electrical impulses coming from the muscle. The test is uncomfortable.
Another test often performed measures nerve conduction velocity (NCV). During this test, electrical impulses are sent down the nerves of the arms and legs. By measuring the speed of these impulses with electrodes placed on the skin, the doctor can determine whether the nerves are functioning normally. This test is also uncomfortable.
Blood enzyme tests are helpful because degenerating muscles become "leaky." They leak enzymes (proteins that speed chemical reactions), which can then be detected in the blood. The presence of these enzymes in the blood at higher than normal levels may be a sign of muscular dystrophy. One such enzyme is creatine kinase, or CK.The CK level is elevated in many forms of muscular dystrophy, some forms resulting in a higher level than others.
Read Part II of Questions and Answers
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