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Muscular Dystrophies

What is Muscular Dystrophy?
The muscular dystrophies (MD) are a group of more than 30
genetic diseases characterized by progressive weakness and
degeneration of the skeletal muscles that control movement.
Some forms of MD are seen in infancy or childhood, while
others may not appear until middle age or later. The disorders
differ in terms of the distribution and extent of muscle
weakness (some forms of muscular dystrophies also affect
cardiac muscle), age of onset, rate of progression, and
pattern of inheritance.

Duchenne muscular dystrophies is the most common form
of MD and primarily affects boys. It is caused by the absence
of dystrophin, a protein involved in maintaining the integrity
of muscle. Onset is between 3 and 5 years and the disorder
progresses rapidly. Most boys are unable to walk by age 12,
and later need a respirator to breathe. Girls in these families
have a 50 percent chance of inheriting and passing the
defective gene to their children. Boys with Becker muscular
dystrophies (very similar to but less severe than Duchenne
muscular dystrophies) have faulty or not enough dystrophin.

Facioscapulohumeral muscular dystrophies usually begins
in the teenage years. It causes progressive weakness in
muscles of the face, arms, legs, and around the shoulders
and chest. It progresses slowly and can vary in symptoms
from mild to disabling.

Myotonic muscular dystrophies is the disorder's most
common adult form and is typified by prolonged muscle
spasms, cataracts, cardiac abnormalities, and endocrine
disturbances. Individuals with myotonic muscular dystrophies
have long, thin faces, drooping eyelids, and a swan-like neck.

Is there any treatment?
There is no specific treatment to stop or reverse any form of
muscular dystrophies. Treatment may include physical
therapy, respiratory therapy, speech therapy, orthopedic
appliances used for support, and corrective orthopedic
surgery. Drug therapy includes corticosteroids to slow muscle
degeneration, anticonvulsants to control seizures and some
muscle activity, immunosuppressants to delay some damage
to dying muscle cells, and antibiotics to fight respiratory
infections. Some individuals may benefit from occupational
therapy and assistive technology. Some patients may need
assisted ventilation to treat respiratory muscle weakness and
a pacemaker for cardiac abnormalities.

What is the prognosis?
The prognosis for people with muscular dystrophies varies
according to the type and progression of the disorder. Some
cases may be mild and progress very slowly over a normal
lifespan, while others produce severe muscle weakness,
functional disability, and loss of the ability to walk. Some
children with MD die in infancy while others live into adulthood
with only moderate disability.

Content Credit NINDS NIH GOV 2006

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