muscular dystrophy

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of a group of progressive muscle disorders caused by a defect in one or more genes that control muscle function and characterized by gradual irreversible wasting of skeletal muscle.
• noun Duchenne's muscular dystrophy.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun pathology A group of genetic diseases which cause progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any of several hereditary diseases of the muscular system characterized by weakness and wasting of skeletal muscles