National Organization for Rare Disorders, Inc.
It is possible that the main title of the report Myotonia Congenita is not the name you expected.
Myotonia congenita is a rare genetic disorder in which an abnormality of voluntary (skeletal) muscle fiber membranes causes an unusually exaggerated response to stimulation (hyperexcitability). As a result, affected individuals have difficulty relaxing certain muscles after contracting them (myotonia), muscle stiffness (rigidity), and associated symptoms. Such symptoms tend to occur when attempting to move certain muscles after rest. In many cases, individuals with myotonia congenita also have abnormal enlargement of the muscles (hypertrophy), resulting in a "herculean" or "body-builder like" appearance.
Two main forms of myotonia congenita have been described: Thomsen disease and Becker disease. In individuals with Thomsen disease, symptoms and findings such as myotonia, associated muscle rigidity, and abnormal muscle enlargement may become apparent from infancy to approximately two to three years of age. In many cases, muscles of the eyelids, hands, and legs may be most affected. Thomsen disease is transmitted as an autosomal dominant trait.
In those with Becker disease, symptoms most commonly become apparent between the ages of four and 12 years. As in Thomsen type myotonia congenita, affected individuals develop myotonia, associated muscle rigidity, and abnormal muscle enlargement (hypertrophy). The symptoms tend to remain constant, with little progression. Becker disease is inherited as an autosomal recessive trait.
Child Neurology Foundation
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- Minneapolis, MN 55415
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Genetic and Rare Diseases (GARD) Information Center
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- Tel: (301)251-4925
- Fax: (301)251-4911
- Tel: (888)205-2311
- Website: http://rarediseases.info.nih.gov/GARD/
Malignant Hyperthermia Association of the United States
- 1 North Main St
- PO Box 1069
- Sherburne, NY 13460
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Muscular Dystrophy Association
- 3300 East Sunrise Drive
- Tucson, AZ 85718-3208
- Tel: (520)529-2000
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- Tel: (800)572-1717
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NIH/National Institute of Arthritis and Musculoskeletal and Skin Diseases
- Information Clearinghouse
- One AMS Circle
- Bethesda, MD 20892-3675
- Tel: (301)495-4484
- Fax: (301)718-6366
- Tel: (877)226-4267
- Email: NIAMSinfo@mail.nih.gov
- Website: http://www.niams.nih.gov/
NIH/National Institute of Neurological Disorders and Stroke
- P.O. Box 5801
- Bethesda, MD 20824
- Tel: (301)496-5751
- Fax: (301)402-2186
- Tel: (800)352-9424
- Website: http://www.ninds.nih.gov/
For a Complete Report
This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".
The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only.
It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.
This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.
Last Updated: 9/17/2007
Copyright 2007 National Organization for Rare Disorders, Inc.
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