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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed November 2011

What is the official name of the RAPSN gene?

The official name of this gene is “receptor associated protein of the synapse.”

RAPSN is the gene's official symbol. The RAPSN gene is also known by other names, listed below.

What is the normal function of the RAPSN gene?

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.

Does the RAPSN gene share characteristics with other genes?

The RAPSN gene belongs to a family of genes called RNF (RING-type zinc fingers).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? ( in the Handbook.

How are changes in the RAPSN gene related to health conditions?

congenital myasthenic syndrome - caused by mutations in the RAPSN gene

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.

Where is the RAPSN gene located?

Cytogenetic Location: 11p11.2

Molecular Location on chromosome 11: base pairs 47,437,757 to 47,449,178

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The RAPSN gene is located on the short (p) arm of chromosome 11 at position 11.2.

The RAPSN gene is located on the short (p) arm of chromosome 11 at position 11.2.

More precisely, the RAPSN gene is located from base pair 47,437,757 to base pair 47,449,178 on chromosome 11.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about RAPSN?

You and your healthcare professional may find the following resources about RAPSN helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the RAPSN gene or gene products?

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

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding RAPSN?

acetylcholine ; acids ; amino acid ; asparagine ; cell ; cell membrane ; congenital ; gene ; lysine ; muscle cell ; muscle cells ; mutation ; neuromuscular junction ; protein ; receptor ; synapse ; syndrome

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Barišić N, Chaouch A, Müller JS, Lochmüller 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. Review. (
  • 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. (
  • Engel AG. Congenital myasthenic syndromes in 2012. Curr Neurol Neurosci Rep. 2012 Feb;12(1):92-101. doi: 10.1007/s11910-011-0234-7. Review. (
  • 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. Review. (
  • 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. (
  • 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. (
  • NCBI Gene (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: November 2011
Published: February 1, 2016