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Reviewed January 2015
What is the official name of the OPN1MW gene?
The official name of this gene is “opsin 1 (cone pigments), medium-wave-sensitive.”
OPN1MW is the gene's official symbol. The OPN1MW gene is also known by other names, listed below.
Read more about gene names and symbols on the About page.
What is the normal function of the OPN1MW gene?
The OPN1MW 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 OPN1MW gene provides instructions for making an opsin pigment that is more sensitive to light in the middle of the visible spectrum (yellow/green light). Cones with this pigment are called middle-wavelength-sensitive or M cones. In response to light, the photopigment triggers a series of chemical reactions within an M 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.
People can have one or more copies of the OPN1MW gene in each cell. All copies of this gene are located in a row on the X chromosome near another opsin pigment gene, OPN1LW. The OPN1LW gene provides instructions for making a photopigment that is more sensitive to light at long wavelengths (in the orange/red part of the visible spectrum). A nearby region of DNA, known as the locus control region (LCR), regulates the activity of the OPN1MW and OPN1LW genes. Only the two opsin pigment genes nearest the LCR, generally the OPN1LW gene and the first copy of the OPN1MW gene, are active in the retina and contribute to color vision.
Does the OPN1MW gene share characteristics with other genes?
The OPN1MW 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 OPN1MW gene related to health conditions?
Where is the OPN1MW gene located?
Cytogenetic Location: Xq28
Molecular Location on the X chromosome: base pairs 154,182,596 to 154,196,861
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The OPN1MW gene is located on the long (q) arm of the X chromosome at position 28.
More precisely, the OPN1MW gene is located from base pair 154,182,596 to base pair 154,196,861 on the X chromosome.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about OPN1MW?
You and your healthcare professional may find the following resources about OPN1MW 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 OPN1MW gene or gene products?
See How are genetic conditions and genes named? in the Handbook.
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding OPN1MW?
amino acid ; arginine ; cell ; chromosome ; cones ; cysteine ; deficiency ; deletion ; DNA ; gene ; locus ; mutation ; photopigment ; photoreceptor ; pigment ; protein ; receptor ; retina ; rods ; spectrum ; tissue ; visual acuity
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (7 links)
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.