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History of Muscular Dystrophy Association
Muscular dystrophy (MD) refers to a group of inherited disorders that all result in chronic muscle weakness. Each of these different types of muscular dystrophy has its own unique clinical features and prognosis (prediction of eventual outcome). Duchene's muscular dystrophy, first described by Edward Meryyon in 1852, is a sex-linked (to the x chromosome) genetic disorder affecting males almost exclusively. A sex-linked disorder is one where the abnormal gene responsible for the disease process is attached to one of the sex chromosomes (x or y) that determine the sex. Males have an x and a y chromosome whereas females have two x chromosomes. Estimates of incidence for Duchene's dystrophy range from 13 to 33 cases per 100,000 live-born males. In up to one-third of cases there is no family history for this disease, suggesting that many are due to new gene mutations. The symptoms of Duchene's dystrophy usually begin at age 3-5 years. Most boys will have trouble keeping up with their friends and will have frequent falls. Running, jumping, and hopping are usually abnormal. By age 5 muscle weakness is demonstrable by EMG. In younger children, the calf muscles are usually enlarged, but the muscle tissue is eventually replaced by fat and connective tissue. By age 8-10 walking usually requires the use of braces. With increasing joint dysfunction and muscle weakness, most children are confined to a wheelchair by age 12. By age 12-13 respiratory muscle function can also be impaired resulting in progressive curvature of the spine (scoliosis). By age 14-18 patients develop serious, sometimes fatal, pulmonary infections. Common complications include pneumonia and aspiration pneumonia. Involvement of the heart muscle is common and referred to as a cardiomyopathy.
This results in weakening of the cardiac muscle contraction that can, on rare occasions, lead to congestive heart failure. Intellectual impairment is common but nonprogressive. Studies have shown that those with Duchene's dystrophy have a mean IQ of less than 75. Recent findings suggest that Duchene's may have some direct effect on the central nervous system (brain). Evaluation will include physical examination and laboratory testing. Blood testing will reveal abnormal elevation in the muscle enzymes (CPK level is elevated 20-100 times normal). Confirmation of the diagnosis is possible with EMG or muscle biopsy. The Neurologist is the expert in the evaluation of suspected cases. There is no definitive cure for Duchene's dystrophy and eventual death due to respiratory failure is common in the second to third decades of life.
Hope this article will provide you information about muscular dystrophy.
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