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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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How is congenital myasthenic syndrome inherited?

Almost all types of CMS are inherited in an autosomal recessive manner. In order to have the autosomal recessive form of CMS, both parents of an affected individual must be carriers of the disease causing mutation. If a person has CMS, but their partner is not a carrier of a CMS mutation, then their children will be carriers but will not have CMS. If one person has CMS and one person is a carrier of CMS, each child has a 50% chance of either being a carrier of CMS or having the disorder.[1]

Only one form of CMS (slow-channel syndrome congenital myasthenic syndrome) has been shown to be inherited in an autosomal dominant manner. This means that if one parent has slow-channel syndrome congenital myasthenic syndrome then all of their children have a 50% chance of inheriting the disorder as well.[1]

It is important to discuss this information with your health care provider, such as a genetic counselor, to accurately determine a person's risk for passing on this disorder.

Last updated: 7/10/2013

  1. Abicht A, Muller J, Lochmuller H. Congenital Myasthenic Syndromes. GeneReviews. June, 28 2012; Accessed 7/1/2013.