Muscular dystrophy

The muscular dystrophies are a group of genetic and hereditary muscle diseases; characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue. In some forms of muscular dystrophy, cardiac and smooth muscles are affected. The muscular dystrophies are the most-known hereditary diseases.

Genetic cause
The most common form is Duchenne muscular dystrophy (DMD). This form is caused by mutations of the gene for the dystrophin protein. The dystrophin gene is the second largest gene in mammals.

The dystrophin gene is located on the X chromosome, thus making DMD a 'sex-linked' disorder. Accordingly, muscular dystrophies are much more common in males, as females have two copies of the X chromosome while males have only one.

Treatment
There is no known cure for muscular dystrophy. Inactivity (such as bed-rest and even sitting for long periods) can worsen the disease. Physical therapy and orthopedic instruments (e.g., wheelchairs, standing frames) may be helpful.

There is no specific treatment for any of the forms of muscular dystrophy. Physical therapy to prevent contractures (a condition in which shortened muscles around joints cause abnormal and sometimes painful positioning of the joints), orthoses (orthopedic appliances used for support) and corrective orthopedic surgery may be needed to improve the quality of life in some cases. The cardiac problems that occur with Emery-Dreifuss muscular dystrophy and myotonic muscular dystrophy may require a pacemaker. The myotonia (delayed relaxation of a muscle after a strong contraction) occurring in myotonic muscular dystrophy may be treated with medications such as quinine, phenytoin or mexiletine.

Types of Muscular Dystrophy

 * Duchenne muscular dystrophy
 * Becker's muscular dystrophy
 * Limb-girdle muscular dystrophy
 * Sarcoglycanopathies
 * Congenital muscular dystrophy
 * Emery-Dreifuss muscular dystrophy
 * Facioscapulohumeral muscular dystrophy
 * Oculopharyngeal muscular dystrophy
 * Fukuyama congenital muscular dystrophy