Global InformationMuscular dystrophy information
| Muscular dystrophy | |
|---|---|
 | |
| In affected muscle (right), the tissue has become disorganized and the concentration of dystrophin (green) is greatly reduced, compared to normal muscle (left). | |
| Specialty | Neuromuscular medicine |
| Symptoms | Increasing weakening, breakdown of skeletal muscles, trouble walking[1][2] |
| Duration | Chronic[1] |
| Types | > 30, including Duchenne muscular dystrophy, Becker muscular dystrophy, facioscapulohumeral muscular dystrophy, limb–girdle muscular dystrophy, myotonic dystrophy[1][2] |
| Causes | Genetic (X-linked recessive, autosomal recessive, or autosomal dominant)[2] |
| Diagnostic method | Genetic testing[2] |
| Treatment | Pharmacotherapy, physical therapy, braces, corrective surgery, assisted ventilation[1][2] |
| Prognosis | Depends on the particular disorder[1] |
Muscular dystrophies (MD) are a genetically and clinically heterogeneous group of rare neuromuscular diseases that cause progressive weakness and breakdown of skeletal muscles over time.[1] The disorders differ as to which muscles are primarily affected, the degree of weakness, how fast they worsen, and when symptoms begin.[1] Some types are also associated with problems in other organs.[2]
Over 30 different disorders are classified as muscular dystrophies.[1][2] Of those, Duchenne muscular dystrophy (DMD) accounts for approximately 50% of cases and affects males beginning around the age of four.[1] Other relatively common muscular dystrophies include Becker muscular dystrophy, facioscapulohumeral muscular dystrophy, and myotonic dystrophy,[1] whereas limb–girdle muscular dystrophy and congenital muscular dystrophy are themselves groups of several – usually extremely rare – genetic disorders.
Muscular dystrophies are caused by mutations in genes, usually those involved in making muscle proteins.[2] The muscle protein, dystrophin, is in most muscle cells and works to strengthen the muscle fibers and protect them from injury as muscles contract and relax.[3] It links the muscle membrane to the thin muscular filaments within the cell. Dystrophin is an integral part of the muscular structure. An absence of dystrophin can cause impairments: healthy muscle tissue can be replaced by fibrous tissue and fat, causing an inability to generate force.[4] Respiratory and cardiac complications can occur as well. These mutations are either inherited from parents or may occur spontaneously during early development.[2] Muscular dystrophies may be X-linked recessive, autosomal recessive, or autosomal dominant.[2] Diagnosis often involves blood tests and genetic testing.[2]
There is no cure for any disorder from the muscular dystrophy group.[1] Several drugs designed to address the root cause are currently available including gene therapy (Elevidys), and antisense drugs (Ataluren, Eteplirsen etc.).[2] Other medications used include glucocorticoids (Deflazacort, Vamorolone); calcium channel blockers (Diltiazem); to slow skeletal and cardiac muscle degeneration, anticonvulsants to control seizures and some muscle activity, and Histone deacetylase inhibitors (Givinostat) to delay damage to dying muscle cells.[1] Physical therapy, braces, and corrective surgery may help with some symptoms[1] while assisted ventilation may be required in those with weakness of breathing muscles.[2]
Outcomes depend on the specific type of disorder.[1] Many affected people will eventually become unable to walk[2] and Duchenne muscular dystrophy in particular is associated with shortened life expectancy.
Muscular dystrophy was first described in the 1830s by Charles Bell.[2] The word "dystrophy" comes from the Greek dys, meaning "no, un-" and troph- meaning "nourish".[2]
- ^ a b c d e f g h i j k l m n "NINDS Muscular Dystrophy Information Page". NINDS. March 4, 2016. Archived from the original on 30 July 2016. Retrieved 12 September 2016.
- ^ a b c d e f g h i j k l m n o p "Muscular Dystrophy: Hope Through Research". NINDS. March 4, 2016. Archived from the original on 30 September 2016. Retrieved 12 September 2016.
- ^ Gao, Q. Q.; McNally, E. M. (2011-01-17). Terjung, Ronald (ed.). Comprehensive Physiology. Vol. 5 (1 ed.). Wiley. pp. 1223–1239. doi:10.1002/cphy.c140048. ISBN 978-0-470-65071-4. PMC 4767260. PMID 26140716.
- ^ Gao, Quan Q.; McNally, Elizabeth M. (2015-06-24). "The Dystrophin Complex: Structure, Function, and Implications for Therapy". Comprehensive Physiology. 5 (3): 1223–1239. doi:10.1002/cphy.c140048. ISBN 9780470650714. PMC 4767260. PMID 26140716.