Muscle tissue is made up of long muscle fibres.
Each fibre is actually an elongated cell that is made up of many individual cells that have fused. Different types of muscular dystrophy are due to errors in different proteins, determined by different genes. Lack of dystrophin causes breakdown of muscle fibres that leads to a specific clinical pattern that has been called Duchenne muscular dystrophy. The clinical picture is closely related to Duchenne, but symptoms are less severe and progression of weakness is slower.