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As of 2010, as many as 16 genes have been associated with eye color inheritance. Some of the eye-color genes include OCA2 and HERC2. [9] [10] The earlier belief that blue eye color is a recessive trait has been shown to be incorrect, and the genetics of eye color are so complex that almost any parent-child combination of eye colors can occur.
The goal of gene therapy studies is to virally supplement retinal cells expressing mutant genes associated with the retinitis pigmentosa phenotype with healthy forms of the gene; thus, allowing the repair and proper functioning of retinal photoreceptor cells in response to the instructions associated with the inserted healthy gene.
Dichromacy in humans is a form of color blindness (color vision deficiency). Normal human color vision is trichromatic, so dichromacy is achieved by losing functionality of one of the three cone cells. The classification of human dichromacy depends on which cone is missing:
The third gene array shows a deuteranopia genotype; the fourth shows a normal color vision genotype. When unequal recombination happens with breaks between the genes (depicted by blue lines), a gene can be essentially deleted from one of the chromosomes. This gene deletion leads to protanopia or deuteranopia (congenital red–green dichromacy).
Rhodopsin, also known as visual purple, is a protein encoded by the RHO gene [5] and a G-protein-coupled receptor (GPCR). It is a light-sensitive receptor protein that triggers visual phototransduction in rod cells. Rhodopsin mediates dim light vision and thus is extremely sensitive to light. [6]
The four pigments in a bird's cone cells (in this example, estrildid finches) extend the range of color vision into the ultraviolet. [1]Tetrachromacy (from Greek tetra, meaning "four" and chroma, meaning "color") is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye.
Individuals homozygous for the gene will have only two opsin classes and therefore exhibit dichromacy. However, heterozygous individuals will have three opsin classes and therefore be trichromats. Since the gene is on the X-chromosome, [6] of which males possess only one, all males are monozygous. They therefore always have 2 opsin classes and ...
Leber's hereditary optic neuropathy (LHON) is a mitochondrially inherited (transmitted from mother to offspring) degeneration of retinal ganglion cells (RGCs) and their axons that leads to an acute or subacute loss of central vision; it predominantly affects adult males, and onset is more likely in younger adults.