Muscular dystrophy is a genetic disorder that causes progressive skeletal muscle weakness. It is characterized by defects in muscle proteins and death of muscle cells and tissue. There is no cure, but treatments include physical therapy, braces, surgery, and drug therapy. It occurs mostly in boys ages 1-4 and the main sign is muscle weakness. Those affected experience a loss of muscle control and mobility over time and most die before age 30 due to respiratory failure.