MUSCULAR DYSTROPHY
The muscular dystrophies (MD) are a group a group of genetic diseases characterized by progressive weakness and degeneration of the skeletal or voluntary muscles and replacement of the dead (apoptotic) muscles by fibrous or other nonfunctional tissues. This causes progressive loss of control of body movement.
The muscles of the heart and chest walls are also affected sooner or later and may be the cause of the cardio-respiratory failure which may be fatal. Other involuntary muscles or organs may get affected in some forms of muscular dystrophy, and a few forms involve other organs as well. 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, age of onset, rate of progression, and pattern of inheritance.
Duchenne MD 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 and regeneration after apoptosis (programmed natural cell death followed by regeneration of the same number and type of cells).Most boys are unable to walk by age 12, and later need a respirator to breathe.