The muscular dystrophies are a group of genetic diseases that cause weakness and muscle wasting, primarily in the skeletal or voluntary muscles (those we control such as the muscles of the arms and legs).
The four types of muscular dystrophy (MD) named here —congenital muscular dystrophy (CMD), distal muscular dystrophy (DD), Emery-Dreifuss muscular dystrophy (EDMD) and oculopharyngeal muscular dystrophy (OPMD)—are among the rarer forms of muscular dystrophy.
Because they’re less common, they can be difficult to diagnose.