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


Reviewed April 2010

What is the official name of the GLRA1 gene?

The official name of this gene is “glycine receptor alpha 1.”

GLRA1 is the gene's official symbol. The GLRA1 gene is also known by other names, listed below.

What is the normal function of the GLRA1 gene?

The GLRA1 gene provides instructions for making one part, the alpha (α)1 subunit, of the glycine receptor protein. The glycine receptor is most abundant in nerve cells (neurons) in the spinal cord and the part of the brain that is connected to the spinal cord (the brainstem). The glycine receptor is made up of five subunits: two α1 subunits and three beta (β) subunits. The β subunit is produced from a different gene.

Receptor proteins have specific sites into which certain other molecules, called ligands, fit like keys into locks. Together, ligands and their receptors trigger signals that affect cell development and function. The ligand for the glycine receptor is the amino acid glycine. This molecule acts as a neurotransmitter, which is a chemical messenger that transmits signals in the nervous system.

When glycine attaches (binds) to the glycine receptor, the receptor opens to allow negatively charged chlorine atoms (chloride ions) to enter the cell. This influx of chloride ions reduces the cell's ability to transmit signals to other cells. Because they stop (inhibit) signaling, glycine receptors are known as inhibitory receptors.

How are changes in the GLRA1 gene related to health conditions?

hereditary hyperekplexia - caused by mutations in the GLRA1 gene

At least 29 mutations in the GLRA1 gene have been found to cause hereditary hyperekplexia. Most of these mutations change single amino acids in the α1 subunit of the glycine receptor protein. The most common mutation replaces the amino acid arginine with the amino acid leucine at protein position 271 (written as Arg271Leu or R271L).

GLRA1 gene mutations that cause hereditary hyperekplexia impair the ability of the glycine receptor protein to respond to the ligand glycine. Some GLRA1 gene mutations alter the structure of the glycine receptor, which prevents the receptor from opening. Other mutations prevent the receptor from reaching the cell membrane. When the glycine receptor is nonfunctional or missing, chloride ions cannot enter the cell, and cell signaling is increased. This overactive cell signaling in the spinal cord and brainstem is thought to cause the abnormal muscle movements, exaggerated startle reaction, and other symptoms of hereditary hyperekplexia.

Where is the GLRA1 gene located?

Cytogenetic Location: 5q32

Molecular Location on chromosome 5: base pairs 151,822,513 to 151,924,866

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

The GLRA1 gene is located on the long (q) arm of chromosome 5 at position 32.

The GLRA1 gene is located on the long (q) arm of chromosome 5 at position 32.

More precisely, the GLRA1 gene is located from base pair 151,822,513 to base pair 151,924,866 on chromosome 5.

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

Where can I find additional information about GLRA1?

You and your healthcare professional may find the following resources about GLRA1 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 GLRA1 gene or gene products?

  • glycine receptor, alpha 1
  • glycine receptor, alpha 1 isoform 1 precursor
  • glycine receptor, alpha 1 isoform 2 precursor
  • STHE

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

What glossary definitions help with understanding GLRA1?

acids ; amino acid ; arginine ; brainstem ; cell ; cell membrane ; chloride ; gene ; glycine ; hereditary ; ions ; leucine ; ligand ; molecule ; mutation ; nervous system ; precursor ; protein ; receptor ; subunit

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


  • Bakker MJ, van Dijk JG, van den Maagdenberg AM, Tijssen MA. Startle syndromes. Lancet Neurol. 2006 Jun;5(6):513-24. Review. (
  • Gene Review: Hyperekplexia (
  • Harvey RJ, Topf M, Harvey K, Rees MI. The genetics of hyperekplexia: more than startle! Trends Genet. 2008 Sep;24(9):439-47. doi: 10.1016/j.tig.2008.06.005. Epub 2008 Aug 15. Review. (
  • Lapunzina P, Sánchez JM, Cabrera M, Moreno A, Delicado A, de Torres ML, Mori AM, Quero J, Lopez Pajares I. Hyperekplexia (startle disease): a novel mutation (S270T) in the M2 domain of the GLRA1 gene and a molecular review of the disorder. Mol Diagn. 2003;7(2):125-8. (
  • Lynch JW. Molecular structure and function of the glycine receptor chloride channel. Physiol Rev. 2004 Oct;84(4):1051-95. Review. (
  • Meinck HM. Startle and its disorders. Neurophysiol Clin. 2006 Sep-Dec;36(5-6):357-64. Epub 2007 Jan 26. Review. (
  • NCBI Gene (
  • Villmann C, Oertel J, Melzer N, Becker CM. Recessive hyperekplexia mutations of the glycine receptor alpha1 subunit affect cell surface integration and stability. J Neurochem. 2009 Nov;111(3):837-47. doi: 10.1111/j.1471-4159.2009.06372.x. Epub 2009 Sep 1. (


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: April 2010
Published: February 8, 2016