Muscular Dystrophy
Webpages concerning "Muscular Dystrophy"
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Wikipedia-Article "Muscular Dystrophy"
| Muscular dystrophy | ||
|---|---|---|
| ICD-10 code: | G71.0 | |
| ICD-9 code: | 359.0-359.1 | |
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 common hereditary diseases.
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Cause
The most common form is Duchenne muscular dystrophy. This form is caused by mutations of the gene for the dystrophin protein. The dystrophin is the second largest gene in mammals. The dystrophin gene is located on the X chromosome (Thus making it a 'sex-linked' disorder. Accordingly, muscular dystrophies are much more common in males, as females have two copies of that chromosome, males have only one). These two facts explain why Duchenne muscular dystrophy is the most common form.
Types
The major types of muscular dystrophy include:
- Becker's muscular dystrophy (OMIM 300376)
- Congenital muscular dystrophy
- Distal muscular dystrophy
- Duchenne muscular dystrophy (OMIM 310200)
- Emery-Dreifuss muscular dystrophy (OMIM 181350, OMIM 310300, OMIM 604929)
- Facioscapulohumeral dystrophy (OMIM 158900, OMIM 158901)
- Fukuyama congenital muscular dystrophy (FCMD) (OMIM 253800)
- Limb-girdle muscular dystrophy (OMIM 159000, OMIM 159001, OMIM 253600, OMIM 253601, OMIM 253700, several others)
- Myotonic muscular dystrophy (OMIM 160900, OMIM 602668, OMIM 605377)
- Oculopharyngeal muscular dystrophy (OMIM 164300)
- Severe childhood autosomal recessive muscular dystrophy (OMIM 253700)
Duchenne MD is the most common form of muscular dystrophy affecting children, and myotonic muscular dystrophy is the most common form affecting adults. Muscular dystrophy can affect people of all ages. Although some forms first become apparent in infancy or childhood, others may not appear until middle age or later.
The most frequent symptoms are muscle weakness (frequent falls, walking problems, eyelid drooping), skeletal and muscle deformities. Neurologic examination often reveals loss of muscle tissue (wasting), muscle contracture, pseudohypertrophy and weakness. Diagnosis is usually established by muscle biopsy, elevated serum creatine kinase levels and electromyography examination, which is consistent with myogenic involvement. Some types of muscular dystrophy may present with additional cardiac disease, intellectual deterioration and infertility.
There is no known cure for muscular dystrophy. Inactivity (such as bedrest and even sitting for long periods) can worsen the disease. Physical therapy and orthopedic instruments (e.g. wheelchairs) may be helpful.
Treatment
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.
Prognosis
The prognosis of muscular dystrophy varies according to the type of muscular dystrophy and the progression of the disorder. Some cases may be mild and very slowly progressive, with normal lifespan, while other cases may have more marked progression of muscle weakness, functional disability and loss of ambulation. Life expectancy may depend on the degree of progression and late respiratory deficit. In Duchenne muscular dystrophy, death usually occurs in the late teens to early 20s, however there are many young men living into the mid 30's. The use of mechanical ventilation and heart medications have been shown to prolong life in DMD.
Current research
The Muscular Dystrophy Association is one of the most prominent disease advocacy organizations in the world, pumping millions of dollars every year into MD research. Jerry Lewis has made a name for himself supporting the organization for over 50 years, and has hosted an annual nationwide telethon every Labor Day since 1966.
The NINDS supports a broad program of research on muscular dystrophy. The goals of these studies are to increase understanding of muscular dystrophy and its cause(s), develop better therapies, and, ultimately, find ways to prevent and cure the disorder.
One promising approach for treatment of muscular dystrophy involves the blocking of myostatin. Another area of research involves modifying the splicing of the dystrophin RNA using steric blocking oligos such as 2'-O methyl phosphorothioates or Morpholinos[1].