There are several types of muscular dystrophy; some form of genetic mutation is responsible for them all. Between the various types of muscular dystrophy, mutations in different genes lead to dysfunction in one or more of the many proteins responsible for normal muscle cell function. Gene mutations can lead to alterations in normal cellular activity, contribute to increased oxidative stress, cause mitochondrial dysfunction, and increase the rate of cell death. As an increasing quantity of muscle cells die over time, they are replaced by fibrotic, adipose (fat), and connective tissue, and the patient’s functional capacity declines (Mayo Clinic 2012; Tidball 2007).
Genetic mutations may be inherited from the parents or may occur spontaneously during reproduction. In the latter case, clinical disease may arise even in children whose parents do not carry a genetic mutation associated with muscular dystrophy (NINDS 2011; Mayo Clinic 2012).
Incidence of muscular dystrophy is dependent upon the specific type of disorder. Duchenne muscular dystrophy (DMD) is the most common type, and the inheritance pattern is sex-linked, occurring at a rate of 1 case per 3500 male births (Dubowitz 1995). Also, people who are born into families with a history of muscular dystrophies have a higher risk of developing them or passing them on to their children (Mayo Clinic 2012).