OPN1SW — Opsin 1, short-wave-sensitive

The OPN1SW gene provides instructions for making a protein called short-wave-sensitive opsin 1, which is essential for normal color vision. This protein is found in the retina, the light-sensitive tissue at the back of the eye. Specifically, it is located in specialized cells called cone photoreceptors, which are responsible for vision in bright light and for color vision. The short-wave-sensitive opsin 1 protein is primarily responsible for detecting blue and violet light. Mutations in the OPN1SW gene can lead to a condition called tritanopia, also known as blue-yellow color blindness. When this gene is mutated, the blue-sensitive cone cells in the retina do not function properly or are absent. As a result, individuals with tritanopia have difficulty distinguishing between blue and green colors, as well as between yellow and red colors. This condition is inherited in an autosomal dominant pattern, meaning that a single copy of the mutated gene is sufficient to cause the disorder.

Gene description: 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. It is essential for normal color vision.

Patient and family guide: The OPN1SW gene provides instructions for making a protein called short-wave-sensitive opsin 1, which is essential for normal color vision. This protein is found in the retina, the light-sensitive tissue at the back of the eye. Specifically, it is located in specialized cells called cone photoreceptors, which are responsible for vision in bright light and for color vision. The short-wave-sensitive opsin 1 protein is primarily responsible for detecting blue and violet light. Mutations in the OPN1SW gene can lead to a condition called tritanopia, also known as blue-yellow color blindness. When this gene is mutated, the blue-sensitive cone cells in the retina do not function properly or are absent. As a result, individuals with tritanopia have difficulty distinguishing between blue and green colors, as well as between yellow and red colors. This condition is inherited in an autosomal dominant pattern, meaning that a single copy of the mutated gene is sufficient to cause the disorder.

Gene function: G protein-coupled photoreceptor that selectively activates G(i) proteins in response to short-wavelength (blue-violet) light, thereby decreasing intracellular cAMP levels. It mediates visual perception of blue light.

Protein structure: G protein-coupled receptor, containing transmembrane helices.

Molecular function: G protein-coupled photoreceptor activity and signaling receptor activity. Activation occurs when the opsin-bound cis-retinal chromophore absorbs a photon and isomerizes to all-trans-retinal, inducing a conformational change in the opsin that triggers a G protein-mediated phototransduction cascade.

Mutation spectrum: Point mutations (missense mutations) such as G>R, T>I, S>P, P>S.

Clinical significance: Mutations in the OPN1SW gene cause tritanopia, an autosomal dominant disorder of human vision characterized by a selective deficiency of blue spectral sensitivity. The aberrant gene products actively interfere with the viability or fidelity of blue-sensitive cone photoreceptors, leading to the loss of blue cone function.

Inheritance: Autosomal Dominant

Chromosomal location: 7q32.1

Research and therapeutic approaches: Currently, there is no cure for tritanopia. Specially tinted eyeglasses designed for the color blind are available. Experimental AAV-mediated gene augmentation therapy has shown promise in rescuing cone structure and function in mouse models with congenital opsin deletion.