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|Distal Muscular Dystrophy|
Distal muscular dystrophy (Distal MD), also called distal myopathy, describes a group of at least six specific muscle diseases that primarily affect distal muscles (those farthest away from the shoulders and hips) in the forearms, hands, lower legs, and feet. Distal dystrophies are typically less severe, progress more slowly, and involve fewer muscles than other forms of MD, although they can spread to other muscles. Distal MD can affect the heart and respiratory muscles, and patients may eventually require the use of a ventilator. Patients may not be able to perform fine hand movement and have difficulty extending the fingers. As leg muscles become affected, walking and climbing stairs become difficult and some patients may be unable to hop or stand on their heels. Onset of distal MD, which affects both men and women, is typically between the ages of 40 and 60 years. In one form of distal MD, a muscle membrane protein complex called dysferlin is known to be lacking.
Although distal MD is primarily an autosomal dominant disorder, autosomal recessive forms have been reported in young adults. Symptoms are similar to those of Duchenne MD but with a different pattern of muscle damage. An infantile-onset form of autosomal recessive distal MD has also been reported. Slow but progressive weakness is often first noticed around age 1, when the child begins to walk, and continues to progress very slowly throughout adult life.