<unk> es <unk>  are a genetically and clinically heterogeneous group of rare neuromuscular diseases that cause progressive weakness and breakdown of skeletal muscles over time. The disorders differ as to which muscles are primarily affected, the degree of weakness, how fast they worsen, and when symptoms begin. Some types are also associated with problems in other organs. Over 30 different disorders are classified as<unk> es. Of those, Duchenne<unk>  (DMD) accounts for approximately 50% of cases and affects males beginning around the age of four. Other relatively common<unk> es include Becker<unk> , facioscapulohumeral<unk> , and myotonic dystrophy, whereas limb–girdle<unk>  and congenital<unk>  are themselves groups of several – usually ultrarare – genetic disorders.<unk> es are caused by mutations in genes, usually those involved in making muscle proteins. These mutations are either inherited from parents or may occur spontaneously during early development.<unk> es may be X-linked recessive, autosomal recessive, or autosomal dominant. Diagnosis often involves blood tests and genetic testing. There is no cure for any disorder from the<unk>  group. Several drugs designed to address the root cause are under development, including gene therapy (Microdystrophin), and antisense drugs (Ataluren, Eteplirsen etc). Other medications used include corticosteroids (Deflazacort), calcium channel blockers (Diltiazem) to slow skeletal and cardiac muscle degeneration, anticonvulsants to control seizures and some muscle activity, and immunosuppressants (Vamorolone) to delay damage to dying muscle cells. Physical therapy, braces, and corrective surgery may help with some symptoms while assisted ventilation may be required in those with weakness of breathing muscles. Outcomes depend on the specific type of disorder. Many affected people will eventually become unable to walk and Duchenne<unk>  in particular is associated with shortened life expectancy.<unk>  was first described in the 1830s by Charles Bell. The word "dystrophy" comes from the Greek dys, meaning "no, un-" and troph- meaning "nourish".
Muscular dystrophy
Charcot–Marie–Tooth disease
Brody myopathy
Chondrodystrophy
Cone dystrophy
Spinal muscular atrophy
Tropical ataxic neuropathy
Nemaline myopathy