DMD and Duchenne muscular dystrophy: Duchenne muscular dystrophy (DMD) is an X-linked recessive disease of muscle that affects 1 in 6000 live males.1 DMD is caused by complete absence of the dystrophin protein in skeletal muscle, myocardium, and brain2 and is characterized by a progressive loss of functional muscle mass leading to deterioration in motor milestones with age.