Myotonia Congenita

National Organization for Rare Disorders, Inc.

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Important
It is possible that the main title of the report Myotonia Congenita is not the name you expected.

Disorder Subdivisions

  • None

General Discussion

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.

Supporting Organizations

Child Neurology Foundation

201 Chicago Ave, #200
Minneapolis, MN 55415
USA
Tel: (952)641-6100
Fax: (952)881-6276
Tel: (877)263-5430
Email: jstone@childneurologyfoundation.org
Website: http://www.childneurologyfoundation.org

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126
Gaithersburg, MD 20898-8126
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
USA
Tel: (607)674-7901
Fax: (607)674-7910
Email: info@mhaus.org
Website: http://www.mhaus.org

Muscular Dystrophy Association

3300 East Sunrise Drive
Tucson, AZ 85718-3208
USA
Tel: (520)529-2000
Fax: (520)529-5300
Tel: (800)572-1717
Email: mda@mdausa.org
Website: http://www.mda.org/

NIH/National Institute of Arthritis and Musculoskeletal and Skin Diseases

Information Clearinghouse
One AMS Circle
Bethesda, MD 20892-3675
USA
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.