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RAPSN gene

receptor associated protein of the synapse

Normal Function

The RAPSN gene provides instructions for making a protein called rapsyn that attaches (binds) to the different parts (subunits) of a protein found in the muscle cell membrane called acetylcholine receptor (AChR). This binding helps keep the receptor subunits together and anchors the AChR protein in the muscle cell membrane. The AChR protein plays a critical role in the normal function of the neuromuscular junction. The neuromuscular junction is the area between the ends of nerve cells and muscle cells where signals are relayed to trigger muscle movement.

Health Conditions Related to Genetic Changes

Congenital myasthenic syndrome

At least 45 mutations in the RAPSN gene have been found to cause congenital myasthenic syndrome. Most of these mutations change single protein building blocks (amino acids) in the rapsyn protein. A common mutation replaces the amino acid asparagine with the amino acid lysine at position 88 in the rapsyn protein (written as Asn88Lys or N88K). Most mutations in the RAPSN gene result in a reduction in functional rapsyn protein. The lack of rapsyn protein results in decreased binding between rapsyn and the AChR protein, which leads to disorganization of the receptor protein in the muscle cell membrane and a reduction in the number of receptors. As a result, signaling at the neuromuscular junction is decreased, which leads to decreased muscle movement and the muscle weakness characteristic of congenital myasthenic syndrome.

More About This Health Condition

Multiple pterygium syndrome

MedlinePlus Genetics provides information about Multiple pterygium syndrome

More About This Health Condition

Other Names for This Gene

  • receptor-associated protein of the synapse
  • RING finger protein 205
  • RNF205

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Barisic N, Chaouch A, Muller JS, Lochmuller H. Genetic heterogeneity and pathophysiological mechanisms in congenital myasthenic syndromes. Eur J Paediatr Neurol. 2011 May;15(3):189-96. doi: 10.1016/j.ejpn.2011.03.006. Epub 2011 Apr 17. Citation on PubMed
  • Beeson D, Webster R, Cossins J, Lashley D, Spearman H, Maxwell S, Slater CR, Newsom-Davis J, Palace J, Vincent A. Congenital myasthenic syndromes and the formation of the neuromuscular junction. Ann N Y Acad Sci. 2008;1132:99-103. doi: 10.1196/annals.1405.049. Citation on PubMed
  • Engel AG. Congenital myasthenic syndromes in 2012. Curr Neurol Neurosci Rep. 2012 Feb;12(1):92-101. doi: 10.1007/s11910-011-0234-7. Citation on PubMed or Free article on PubMed Central
  • Engel AG. Current status of the congenital myasthenic syndromes. Neuromuscul Disord. 2012 Feb;22(2):99-111. doi: 10.1016/j.nmd.2011.10.009. Epub 2011 Nov 21. Citation on PubMed or Free article on PubMed Central
  • Kinali M, Beeson D, Pitt MC, Jungbluth H, Simonds AK, Aloysius A, Cockerill H, Davis T, Palace J, Manzur AY, Jimenez-Mallebrera C, Sewry C, Muntoni F, Robb SA. Congenital myasthenic syndromes in childhood: diagnostic and management challenges. J Neuroimmunol. 2008 Sep 15;201-202:6-12. doi: 10.1016/j.jneuroim.2008.06.026. Epub 2008 Aug 15. Citation on PubMed
  • Milone M, Shen XM, Selcen D, Ohno K, Brengman J, Iannaccone ST, Harper CM, Engel AG. Myasthenic syndrome due to defects in rapsyn: Clinical and molecular findings in 39 patients. Neurology. 2009 Jul 21;73(3):228-35. doi: 10.1212/WNL.0b013e3181ae7cbc. Citation on PubMed or Free article on PubMed Central

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.