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Genetic and Rare Diseases Information Center (GARD)

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Congenital myasthenic syndrome

Other Names for this Disease
  • CMS
  • Congenital Myasthenia
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Congenital myasthenic syndrome (CMS) is a group of genetic disorders that result in muscle weakness and fatigue. Symptoms can range from mild weakness to progressive disabling weakness.[1] There are three main subtypes of CMS, which are defined by how they affect the connection between muscles and the nervous system: postsynaptic (75-80% of patients), synaptic (14-15% of patients), and presynaptic (7-8% of patients).[2] Identification of the specific subtype is important in patient care for determining the most effective treatment.[2] Mutations in many genes have been found to cause CMS, and most forms of CMS are inherited in an autosomal recessive pattern. One form of CMS, a postsynaptic form known as slow-channel syndrome congenital myasthenic syndrome is inherited in an autosomal dominant manner.[1][2]
Last updated: 7/10/2013


  1. Abicht A, Muller J, Lochmuller H. Congenital Myasthenic Syndromes. GeneReviews. June, 28 2012; Accessed 7/1/2013.
  2. Lorenzoni PJ, Scola RH, Kay CSK, Werneck LC. Congenital Myasthenic syndrome: A Brief Review. Pediatric Neurology. 2012; 22353287. Accessed 7/1/2013.
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Basic Information

  • The Web site provides further information on this topic. Click on to view the information page.
  • Genetics Home Reference (GHR) contains information on Congenital myasthenic syndrome. This website is maintained by the National Library of Medicine.
  • Muscular Dystrophy Association has information and resources about congenital myasthenic syndrome.

In Depth Information

  • OrphaNet is a European reference portal for information on rare diseases and orphan drugs.  Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Congenital myasthenic syndrome. Click on the link to view a sample search on this topic.