muscular dystrophy


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Related to muscular dystrophy: multiple sclerosis, Duchenne muscular dystrophy

muscular dystrophy

(dĭs`trōfē), any of several inherited diseases characterized by progressive wasting of the skeletal muscles. There are five main forms of the disease. They are classified according to the age at onset of symptoms, the pattern of inheritance, and the part of the body primarily affected.

Types of Muscular Dystrophy

The most common form of muscular dystrophy, Duchenne, was first described by the French physician Guillaume Benjamin Amand DuchenneDuchenne, Guillaume Benjamin Amand
, 1806–75, French physician. He is noted for researches on diseases of the muscular and nervous systems and for his pioneer work on the use of electricity in the diagnosis and treatment of disease.
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 in 1861. Most cases are caused by a recessive sex-linked gene located on the X chromosome and carried only by females. Each son of a carrier has a 50% chance of inheriting the gene and developing the disease. Each daughter has a 50% chance of inheriting the gene and becoming a carrier. In small number of "sporadic" cases there is no family history. The disease begins with leg weakness before age 3 and progresses rapidly, with death often occurring before age 30, often because of involvement of lung or heart muscle. Research has shown that the abnormal gene fails to produce an essential skeletal muscle protein called dystrophin. Becker's muscular dystrophy is similar to the Duchenne form, but appears somewhat later in life and progresses more slowly.

Fascioscapulohumeral muscular dystrophy primarily involves facial and shoulder muscles and affects both sexes. Symptoms can begin from adolescence to around age 40. It is caused by an autosomal dominant trait (at least one parent will have the disease). Progression is usually slow and severe disability is unusual.

Myotonic muscular dystrophy is another autosomally dominant disease affecting both sexes. It appears to be caused by the repetition of a section of DNA on chromosome 4. In a surprising development, researchers found that the number of repetitions on the chromosome increase and the disease becomes more severe with each generation. It is characterized by an inability of the muscles to relax properly after contraction and primarily affects the muscles of the hands and feet. It usually begins in adulthood and is often accompanied by cataracts, baldness, and abnormal endocrine function.

The limb-girdle form of the disease first affects the muscles of the hip and shoulder areas. Symptoms usually become apparent in late adolescence or early adulthood. Caused by an autosomal recessive trait (carried by a gene passed on by both asymptomatic parents), it can affect males and females alike. This form usually progresses slowly.

Treatment

There is no known cure for muscular dystrophy. Corticosteriods may slow the destruction of muscle tissue in persons with Duchenne muscular dystrophy, and phenytoin, procainamide, or quinine is used to treat delayed muscle relaxation in myotonic muscular dystrophy. Scientists have identified genetic abnormalities responsible for multiple dystrophy, and some treatments focusing on those mutations are being explored. Exon-skipping drugs, which use RNA-splicing to allow muscle cells to produce a form of dystrophin that can function, are being studied for Duchenne muscular dystrophy, and one such drug has been approved for patients with one genetic mutation. Supportive measures and exercises can improve the quality of life and preserve mobility for as long as possible. Genetic screening is recommended for all family members who might be carriers. Prenatal tests such as chorionic villus samplingchorionic villus sampling
(CVS) or chorionic villus biopsy
(CVB) , diagnostic procedure in which a sample of chorionic villi from the developing placenta is removed from the uterus of a pregnant woman (see pregnancy) using a fine needle inserted through the abdomen or
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 and amniocentesisamniocentesis
, diagnostic procedure in which a sample of the amniotic fluid surrounding a fetus is removed from the uterus by means of a fine needle inserted through the abdomen of the pregnant woman (see pregnancy).
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 can detect some forms of muscular dystrophy early in a pregnancy.

Bibliography

See A. E. H. Emery, Muscular Dystrophy: The Facts (1994).

muscular dystrophy

[′məs·kyə·lər ′dis·trə·fē]
(medicine)
A group of diseases characterized by degeneration of or injury to individual muscle cells, not primarily involving the nerve supply; the most common form is Duchenne-Greisinger disease.

muscular dystrophy

a genetic disease characterized by progressive deterioration and wasting of muscle fibres, causing difficulty in walking
References in periodicals archive ?
About Duchenne Muscular Dystrophy Duchenne muscular dystrophy (DMD) is a genetic disorder occurring primarily in boys that is characterized by rapidly progressive muscle degeneration and weakness.
To support the Muscular Dystrophy Campaign, contact Sarah Clark at s.
Duchenne muscular dystrophy has been part of our lives for years, and all the children who live with it are very brave - there is no way the NHS should not fund the treatment Translarna.
Sue's husband, David, and their daughter, Laura, both have muscular dystrophy.
Becker muscular dystrophy results from a genetic defect that reduces the amount of a protein called dystrophin in the membrane of muscle cells.
A review of the Muscular Dystrophy products under development by companies and universities/research institutes based on information derived from company and industry-specific sources.
For more details about the Big Fun Run please email the Muscular Dystrophy Campaign Regional Office at northwest@muscular-dystrophy.
A research team, which is analysing his DNA, believe that if they can pinpoint the protective mechanism then it could lead to a successful treatment for muscular dystrophy in humans.
Here at the Muscular Dystrophy Campaign we have given them the tools to go out and investigate these issues and campaign for equality, but it's the Trailblazers themselves, like Jennifer Gallacher, who have made the project such a success.
Bradley's mum, Sarah Thompson, said: "When Bradley was diagnosed I felt like the rug was ripped from under me but things have got better thanks to the support of Muscular Dystrophy Campaign.
As Tesco Charity of the Year 2009, the Muscular Dystrophy Campaign is aiming to raise pounds 3m to provide vital, specialist equipment such as powered wheelchairs and electric beds, for the 8,000 children in the UK who have a muscle-wasting disease.
Halpin, executive vice president of Platinum Maintenance Corporation, dinner chair, and national vice president of the Muscular Dystrophy Association noted, "We are proud to have exceeded our goal by over $200,000 dollars.

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