Muscular dystrophy refers to a group of diseases that gradually cause muscles to weaken. MD is a genetic disorder, passed from parent to child through genes. These disorders vary in many ways. Some affect children, others adts. Some disorders are very severe and get worse fast; others cause fewer problems and worsen slowly. In most cases, however, people with MD become unable to walk. While there is no cure, treatment can help people do things for themselves for as long as possible and prevent complications.