Muscular Dystrophy: any of a group of hereditary diseases marked by progressive wasting of certain "muscles." (Oxford)

A general term for a group of inherited disorders which are characterized by progressive degeneration of skeletal muscles. (MeSH) A group of inherited progressive muscle disorders characterized by muscle weakness and eventual death of the muscle tissues. Examples include “Duchenne muscular dystrophy” and “Becker's muscular dystrophy.” (NCIt) All of the muscles may be affected. Or, only specific groups of muscles may be affected, such as those around the pelvis, shoulder, or face. Muscular dystrophy can affect adults, but the more severe forms tend to occur in early childhood. (PubMedHealth2))

Becker Muscular Dystrophy: an “X-linked” inherited disorder characterized by slowly progressing weakness in the muscles of the legs and pelvis. (NCIt) Closely related condition (to Duchenne muscular dystrophy) featuring a later onset of disease (usually in adolescence) and a slowly progressive course. (MeSH) Primarily affects skeletal muscles, which are used for movement, and heart (cardiac) muscle. Associated with “cardiomyopathy.” This form of heart disease weakens the cardiac muscle, preventing the heart from pumping blood efficiently. (GHR)

Duchenne Muscular Dystrophy: an X-linked inherited disorder characterized by rapidly progressing muscle weakness and muscle atrophy initially involving the lower extremities and eventually affecting the whole body. (NCIt) An inherited disorder that involves muscle weakness, which quickly gets worse. Caused by a defective gene that makes “dystrophin.” Because of the way the disease is inherited, boys are affected, not girls. The sons of females who are carriers of the disease (women with a defective gene but no symptoms themselves) each have a 50% chance of getting the disease. The daughters each have a 50% chance of being carriers. (PubMedHealth2) An X-linked recessive muscle disease caused by an inability to synthesize dystrophin. Muscle fibers undergo a process that features degeneration and regeneration. Clinical manifestations include weakness in the first few years of life, cardiomyopathy, and an increased incidence of impaired (mental activity). (MeSH) Duchenne and Becker muscular dystrophies together affect 1 in 3,500 to 5,000 newborn males worldwide. Between 400 and 600 boys in the United States are born with these conditions each year. (GHR)

Myotonic Dystrophy: an inherited progressive disorder affecting the muscles. (NCIt) Characterized by progressive muscle wasting and weakness. People with this disorder often have prolonged muscle contractions (myotonia) and are not able to relax certain muscles after use. For example, a person may have difficulty releasing their grip on a doorknob or handle. Also, affected people may have slurred speech or temporary locking of their jaw. Caused by mutations in the ‘DMPK’ gene (and) the ‘CNBP’ gene. The specific functions of these genes are unclear. Most common form of muscular dystrophy that begins in adulthood. Affects at least 1 in 8,000 people worldwide. (GHR)