Neuromuscular disorders are conditions that affect the nerve, muscle, or neuromuscular junction. (This is where the nerve talks to the muscle.) Muscular dystrophy is a group of inherited diseases that cause weakness. They also cause wasting away of muscle tissue. There are many types of muscular dystrophy. Each type leads to loss of strength, disability that gets worse, and possible deformity.
The most common type is Duchenne muscular dystrophy. The next most common is Becker muscular dystrophy.
There are nine major types of muscular dystrophy. Each type differs in the muscles affected, the age of onset, and its rate of progress. They are named for the muscles that are affected.
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Type
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Age at onset
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Symptoms, rate of progress, and life expectancy
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Becker
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Teen to early adulthood
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Symptoms are almost the same as Duchenne, but less severe. It progresses more slowly than Duchenne. Survival goes into mid to late adulthood. Becker disease is almost always limited to males. This is the same as with Duchenne.
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Congenital
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Birth
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Symptoms include general muscle weakness and possible joint deformities. The disease progresses slowly. It causes a shortened life span.
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Duchenne
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Ages 2 to 6
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Symptoms include general muscle weakness and wasting. It affects the pelvis, upper arms, and upper legs. Over time, it includes all voluntary muscles. Survival beyond the 20s is rare. It happens mostly in boys. Very rarely it can affect women, who have much milder symptoms and a better prognosis.
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Distal
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Ages 40 to 60
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Symptoms include weakness and wasting of muscles of the hands, forearms, and lower legs. The progress is slow. It rarely leads to total disability.
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Emery-Dreifuss
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Childhood to early teens
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Symptoms include weakness and wasting of shoulder, upper arm, and shin muscles. Joint deformities are common. The progress is slow. Sudden death may occur from cardiac problems.
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Facioscapulohumeral
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Childhood to early adults
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Symptoms include facial muscle weakness and weakness with some wasting of shoulders and upper arms. Progress is slow with periods of rapidly getting worse. Life span may be many decades after onset.
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Limb-Girdle
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Late childhood to middle age
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There are many forms with varying degrees of symptoms which include weakness and wasting that affects shoulder girdle and pelvic girdle first. Progress is slow. Death is most often due to cardiopulmonary problems.
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Myotonic
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Ages 20 to 40
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Symptoms include weakness of all muscle groups and delayed relaxing of muscles after contraction. It affects the face, feet, hands, and neck first. Progress may be slow, sometimes spanning 50 to 60 years. A form that affects infants causes more severe problems.
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Oculopharyngeal
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Ages 40 to 70
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Symptoms affect muscles of eyelids and throat causing throat muscles to weaken. Over time, this causes inability to swallow and severe weight loss from lack of food. Progress is slow.
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