A mouse bred to have the same genetic mutation as people with myotonic dystrophy provides important clues about the cause of muscle wasting in the disorder, the most common form of muscular dystrophy that begins in adulthood. Unlike previous mouse models of the disease, these animals have a genetic mutation that causes the muscle wasting that is the most devastating element of this inherited disorder, said one of the researchers, who is also a professor of pathology and molecular and cellular biology.