DMD is caused by an absence of *dystrophin* protein that helps keep muscle cells intact. Symptom onset is in early childhood usually between ages 3 and 5 Commonly boys. The disease primarily affects boys, but in rare cases it can affect girls.
*Symptoms of DMD*
_Muscle weakness_ can begin as early as age 3, first affecting the muscles of the hips, pelvic muscles, thighs and shoulders, and later the skeletal (voluntary) muscles in the arms, legs and trunk. The calves often are enlarged. By the early teens, the heart and respiratory muscles also are affected. For more about DMD symptoms, see Signs and Symptoms.
Becker muscular dystrophy (BMD) is a milder version of DMD. Its onset is usually in the teens or early adulthood, and the course is slower and less predictable than that of DMD.
*Causes*
first described by the French neurologist *Guillaume Benjamin Amand Duchenne* in the 1860s, but until the 1980s, little was known about the cause of any kind of muscular dystrophy. In 1986. the protein associated with this gene was identified and named dystrophin. Lack of the dystrophin protein in muscle cell.
Mutation on gene "locus xp21"
DMD has an X-linked recessive inheritance pattern and is passed on by the mother, who is referred to as acarrier. For more about the way gene mutations cause Duchenne dystrophy, see Causes/Inheritance.
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(Source:Internet)
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