Duchenne is a genetic disease caused by a mutation, or change, in the gene that encodes for dystrophin. Dystrophin is a protein that is present in every muscle fibre in the body. Dystrophin acts as a “shock absorber” that allows muscles to contract and relax without being damaged. Without dystrophin, muscles are not able to function or repair themselves properly. Additionally, the muscle membrane is easily damaged by normal day-to-day activity, creating tiny microtears in the cell membrane. Without dystrophin, the muscles are not able to repair themselves. These tiny tears let calcium come into the cell, which is a toxic substance to muscle. The calcium damages and eventually kills the muscle cells, allowing them to be replaced with scar tissue and fat. The loss of muscle cells results in a loss of strength and function over time.