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Distal myopathy 2
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Reviewed November 2011
What is distal myopathy 2?
Distal myopathy 2 is a condition characterized by weakness of specific muscles that begins in adulthood. It is a form of muscular dystrophy that specifically involves muscles in the throat, lower legs, and forearms. Muscles farther from the center of the body, like the muscles of the lower legs and forearms, are known as distal muscles.
Muscle weakness in the ankles is usually the first symptom of distal myopathy 2. The weakness can also affect muscles in the hands, wrists, and shoulders. At first, the muscle weakness may be on only one side of the body, but both sides are eventually involved. This muscle weakness can slowly worsen and make actions like walking and lifting the fingers difficult.
Another characteristic feature of distal myopathy 2 is weakness of the vocal cords and throat. This weakness initially causes the voice to sound weak or breathy (hypophonic). Eventually, the voice becomes gurgling, hoarse, and nasal. The weakness can also cause difficulty swallowing (dysphagia).
How common is distal myopathy 2?
The prevalence of distal myopathy 2 is unknown. At least two families with the condition have been described in the scientific literature.
What genes are related to distal myopathy 2?
A mutation in the MATR3 gene has been identified in people with distal myopathy 2. This gene provides instructions for making a protein called matrin 3, which is found in the nucleus of the cell as part of the nuclear matrix. The nuclear matrix is a network of proteins that provides structural support for the nucleus and aids in several important nuclear functions.
The function of the matrin 3 protein is unknown. This protein can attach to (bind) RNA, which is a chemical cousin of DNA. Some studies indicate that matrin 3 binds and stabilizes a type of RNA called messenger RNA (mRNA), which provides the genetic blueprint for proteins. Matrin 3 may also bind certain abnormal RNAs that might lead to nonfunctional or harmful proteins, thereby blocking the formation of such proteins. Other studies suggest that the matrin 3 protein may be involved in cell survival.
The MATR3 gene mutation identified in people with distal myopathy 2 changes a single protein building block (amino acid) in the matrin 3 protein. The effect of this mutation on the function of the protein is unknown, although one study suggests that the mutation may change the location of the protein in the nucleus. Researchers are working to determine how this gene mutation leads to the signs and symptoms of distal myopathy 2.
Read more about the MATR3 gene.
How do people inherit distal myopathy 2?
Distal myopathy 2 is inherited in an autosomal dominant pattern, which means one copy of the altered MATR3 gene in each cell is sufficient to cause the disorder.
Where can I find information about diagnosis or management of distal myopathy 2?
These resources address the diagnosis or management of distal myopathy 2 and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about distal myopathy 2?
You may find the following resources about distal myopathy 2 helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for distal myopathy 2?
What if I still have specific questions about distal myopathy 2?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding distal myopathy 2?
amino acid ; autosomal ; autosomal dominant ; cell ; difficulty swallowing ; distal ; DNA ; dysphagia ; gene ; messenger RNA ; mRNA ; muscular dystrophy ; mutation ; nucleus ; prevalence ; protein ; RNA ; symptom
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (5 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.