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


Reviewed January 2015

What is the official name of the OPN1SW gene?

The official name of this gene is “opsin 1 (cone pigments), short-wave-sensitive.”

OPN1SW is the gene's official symbol. The OPN1SW gene is also known by other names, listed below.

What is the normal function of the OPN1SW gene?

The OPN1SW gene provides instructions for making a protein that is essential for normal color vision. This protein is found in the retina, which is the light-sensitive tissue at the back of the eye. The retina contains two types of light receptor cells, called rods and cones, that transmit visual signals from the eye to the brain. Rods provide vision in low light. Cones provide vision in bright light, including color vision. There are three types of cones. each containing a specific pigment (a photopigment called an opsin) that is most sensitive to particular wavelengths of light.

The OPN1SW gene provides instructions for making an opsin pigment that is more sensitive to light in the blue/violet part of the visible spectrum (short-wavelength light). Cones with this pigment are called short-wavelength-sensitive or S cones. In response to light, the photopigment triggers a series of chemical reactions within an S cone. These reactions ultimately alter the cell's electrical charge, generating a signal that is transmitted to the brain. The brain combines input from all three types of cones to produce normal color vision.

Does the OPN1SW gene share characteristics with other genes?

The OPN1SW gene belongs to a family of genes called GPCR (G protein-coupled receptors).

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 OPN1SW gene related to health conditions?

color vision deficiency - caused by mutations in the OPN1SW gene

At least six mutations in the OPN1SW gene have been found to cause a relatively uncommon form of color vision deficiency called blue-yellow color vision defects or tritan defects. These defects cause problems with differentiating shades of blue and green and cause difficulty distinguishing dark blue from black. Each of the known OPN1SW gene mutations changes a single protein building block (amino acid) in the short-wave-sensitive photopigment, which causes the photopigment to be partially or totally nonfunctional. Researchers suggest that S cone cells without functional photopigment die prematurely or cannot transmit visual signals to the brain normally.

When OPN1SW gene mutations lead to completely nonfunctional S cones, color vision depends entirely on the other two types of cones. The specific type of blue-yellow color vision deficiency that results from a total loss of S cone function is called tritanopia. A less severe blue-yellow color vision defect called tritanomaly occurs when S cones function abnormally.

Where is the OPN1SW gene located?

Cytogenetic Location: 7q32.1

Molecular Location on chromosome 7: base pairs 128,772,489 to 128,775,790

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

The OPN1SW gene is located on the long (q) arm of chromosome 7 at position 32.1.

The OPN1SW gene is located on the long (q) arm of chromosome 7 at position 32.1.

More precisely, the OPN1SW gene is located from base pair 128,772,489 to base pair 128,775,790 on chromosome 7.

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

Where can I find additional information about OPN1SW?

You and your healthcare professional may find the following resources about OPN1SW 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 OPN1SW gene or gene products?

  • BCP
  • blue cone photoreceptor pigment
  • blue cone pigment
  • blue-sensitive opsin
  • BOP
  • short-wave-sensitive pigment
  • S-pigment

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

What glossary definitions help with understanding OPN1SW?

amino acid ; cell ; cones ; deficiency ; gene ; photopigment ; photoreceptor ; pigment ; protein ; receptor ; retina ; rods ; spectrum ; tissue

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


  • Baraas RC, Carroll J, Gunther KL, Chung M, Williams DR, Foster DH, Neitz M. Adaptive optics retinal imaging reveals S-cone dystrophy in tritan color-vision deficiency. J Opt Soc Am A Opt Image Sci Vis. 2007 May;24(5):1438-47. (
  • Baraas RC, Hagen LA, Dees EW, Neitz M. Substitution of isoleucine for threonine at position 190 of S-opsin causes S-cone-function abnormalities. Vision Res. 2012 Nov 15;73:1-9. doi: 10.1016/j.visres.2012.09.007. Epub 2012 Sep 26. (
  • Calkins DJ. Seeing with S cones. Prog Retin Eye Res. 2001 May;20(3):255-87. Review. (
  • Deeb SS. Molecular genetics of color-vision deficiencies. Vis Neurosci. 2004 May-Jun;21(3):191-6. Review. (
  • Gunther KL, Neitz J, Neitz M. A novel mutation in the short-wavelength-sensitive cone pigment gene associated with a tritan color vision defect. Vis Neurosci. 2006 May-Aug;23(3-4):403-9. (
  • NCBI Gene (
  • Neitz J, Neitz M. The genetics of normal and defective color vision. Vision Res. 2011 Apr 13;51(7):633-51. doi: 10.1016/j.visres.2010.12.002. Epub 2010 Dec 15. Review. (


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: January 2015
Published: February 8, 2016