Muscular Dystrophy
Contents
What Is
Muscular Dystrophy?
The muscular dystrophies (MD) are a group of genetic diseases
characterized by progressive weakness and degeneration of the
skeletal muscles that control movement. There are many forms of
muscular dystrophy, some noticeable at birth (congenital muscular
dystrophy), others in adolescence (Becker MD), but the 3 most common
types are Duchenne, facioscapulohumeral, and myotonic. These three
types differ in terms of pattern of inheritance, age of onset, rate
of progression, and distribution of weakness.
Duchenne MD primarily affects boys and is the result of
mutations in the gene that regulates dystrophin - a protein involved
in maintaining the integrity of muscle fiber. Onset is between 3-5
years and progresses rapidly. Most boys become unable to walk at 12,
and by 20 have to use a respirator to breathe.
Facioscapulohumeral MD appears in adolescence and causes
progressive weakness in facial muscles and certain muscles in the
arms and legs. It progresses slowly and can vary in symptoms from
mild to disabling.
Myotonic MD varies in the age of onset and is characterized by
myotonia (prolonged muscle spasm) in the fingers and facial muscles;
a floppy-footed, high-stepping gait; cataracts; cardiac
abnormalities; and endocrine disturbances. Individuals with myotonic
MD have long faces and drooping eyelids; men have frontal baldness.
Is There Any
Treatment for Muscular Dystrophy?
There is no specific treatment for any of the forms of MD.
Respiratory therapy, physical therapy to prevent painful muscle
contractures, orthopedic appliances used for support, and
corrective orthopedic surgery may be needed to improve the quality
of life in some cases. Cardiac abnormalities may require a
pacemaker. Corticosteroids such as prednisone can slow the rate of
muscle deterioration in patients with Duchenne MD but causes side
effects. Myotonia is usually treated with medications such as
mexiletine, phenytoin, or quinine.
What Is the Prognosis for Someone With Muscular Dystrophy?
The prognosis of MD varies according to the type of MD and the
progression of the disorder. Some cases may be mild and progress
very slowly over a normal lifespan, while other cases may have
more marked progression of muscle weakness, functional disability,
and loss of the ability to walk. In Duchenne MD, death usually
occurs in the early 20s.
What
Research Is Being Done?
The NINDS supports a broad program of research on MD. The goals of
these studies are to understand MD and to develop techniques to
diagnose, treat, prevent, and ultimately cure muscular dystrophy.
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