Becker muscular dystrophy

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

• noun A variant of Duchenne's muscular dystrophy in which symptoms of muscle weakness are milder, progress at a slower and less predictable rate, and do not appear until late childhood or early adulthood.

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

• noun a form of muscular dystrophy that sets in in adolescence or adulthood and progresses slowly but will affect all voluntary muscles; characterized by generalized weakness and muscle wasting that affects limb and trunk muscles first; similar to Duchenne's muscular dystrophy but less severe; inheritance is X-linked recessive (carried by females but affecting only males)