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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.
The OPN1SW gene provides instructions for making a protein that is essential for normal color vision. This gene is active in the retina, a light-sensitive tissue at the back of the eye. The retina contains two types of light receptor cells called rods and cones. Rods are responsible for vision in low light. Cones provide vision in bright light, including color vision. Three types of cones each contain a special pigment (a photopigment) that is most sensitive to a particular wavelength of light.
The OPN1SW gene produces a photopigment that is more sensitive to light at the blue/violet end of the visible spectrum. Cones with this pigment are usually called short-wavelength-sensitive or S cones. In response to light at shorter wavelengths, the photopigment triggers a series of chemical reactions within an S cone cell. 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.
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? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genefamilies) in the Handbook.
Three mutations in the OPN1SW gene have been identified in people with blue-yellow color vision deficiency. These mutations cause a rare vision defect that makes it difficult or impossible to distinguish between shades of blue and green. Each of the three known OPN1SW mutations changes a single protein building block (amino acid) in the short-wave-sensitive photopigment. One mutation replaces glycine with arginine at position 79 (written as Gly79Arg), another mutation replaces serine with proline at position 214 (Ser214Pro), and a third mutation replaces proline with serine at position 264 (Pro264Ser). All of these genetic changes inactivate the photopigment by disrupting its structure or stability. Researchers suggest that S cone cells with a nonfunctional photopigment die prematurely or cannot transmit visual signals to the brain. This loss of S cones impairs the perception of blue and leads to confusion between shades of blue and green.
When S cones are completely nonfunctional, the specific type of blue-yellow color vision deficiency that results is called tritanopia. A less severe blue-yellow color vision defect called tritanomaly occurs when S cones function abnormally.
Cytogenetic Location: 7q32.1
Molecular Location on chromosome 7: base pairs 128,772,488 to 128,775,789
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 128,772,488 to base pair 128,775,789 on chromosome 7.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
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.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
amino acid ; arginine ; cell ; cone cell ; cones ; deficiency ; gene ; glycine ; mutation ; perception ; photopigment ; photoreceptor ; pigment ; proline ; protein ; receptor ; retina ; rods ; serine ; spectrum ; tissue
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).
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? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.