The Muscular Dystrophies (MD) are a group of more than 30 genetic diseases characterized by progressive weakness and degeneration of the skeletal muscles that control movement. 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 (some forms of MD also affect cardiac muscle), age of onset, rate of progression, and pattern of inheritance.
The most common types of Muscular Dystrophy appear to be due to a genetic deficiency of the muscle protein dystrophin. There’s no cure for Muscular Dystrophy as of yet, but medications and therapy can slow the course of the disease.
You can find more information at these sites:
mda.org
wikipedia.org/muscular_dystrophy
medicalnewstoday.com/muscular_dystrophy