Myotonia Congenita

National Organization for Rare Disorders, Inc.

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

Disorder Subdivisions

  • Thomsen Disease (THD); Myotonia Congenita, Autosomal Dominant
  • Becker Disease; Myotonia Congenita, Autosomal Recessive (MCR); Generalized

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.

Resources

Malignant Hyperthermia Association of the United States (MHAUS)
11 East State Street
PO Box 1069
Sherburne, NY 13460-1069
USA
Tel: (607)674-7901
Fax: (607)674-7910
Email: info@mhaus.org
Internet: http://www.mhaus.org

Muscular Dystrophy Association
3300 E. Sunrise Dr
Tucson, AZ 85718
USA
Tel: (520)529-2000
Fax: (520)529-5300
Tel: (800)572-1717
Email: mda@mdausa.org
Internet: http://www.mda.org/

NIH/National Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse
1 AMS Circle
Bethesda, MD 20892-3675
USA
Tel: (301)495-4484
Fax: (301)718-6366
Tel: (877)226-4267
TDD: (301)565-2966
Email: NIAMSinfo@mail.nih.gov
Internet: http://www.niams.nih.gov/Health_Info

National Institute of Neurological Disorders and Stroke (NINDS)
P.O. Box 5801
Bethesda, MD 20824
Tel: (301)496-5751
Fax: (301)402-2186
Tel: (800)352-9424
TDD: (301)468-5981
Email: me20t@nih.gov
Internet: http://www.ninds.nih.gov/

MUMS National Parent-to-Parent Network
150 Custer Court
Green Bay, WI 54301-1243
USA
Tel: (920)336-5333
Fax: (920)339-0995
Tel: (877)336-5333
Email: mums@netnet.net
Internet: http://www.netnet.net/mums/

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
TDD: (888)205-3223
Email: ordr@od.nih.gov
Internet: http://rarediseases.info.nih.gov/Default.aspx

Child Neurology Foundation
2000 West 98th Street
Bloomington, MN 55431
USA
Tel: (952)641-6100
Fax: (952)881-6276
Tel: (800)263-5430
Email: jstone@childneurologyfoundation.org
Internet: http://www.childneurologyfoundation.org

For a Complete Report

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html

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