Duchenne muscular dystrophy (DMD) is a genetically X-linked disorder of skeletal muscle
characterized by progressive muscle atrophy. DMD is caused by various mutations in the DMD gene which result in a loss of the skeletal muscle protein dystrophin (Dys). One in 3500-6000 boys are affected with DMD, making DMD the most common of the human muscular dystrophies. Dys has been localized to the muscle cell plasmalemma by electron-microscopic immunoperoxidase techniques, and appears to be a cytoskeletal protein. The main function of Dys is the maintenance of mechanical stability at the muscle cell membrane so normal stresses encountered during contraction can be withstood without membrane disruption.