A study in Rotterdam (2009) found that it was possible to predict eye color with more than 90% accuracy for brown and blue using just six SNPs. The actual number of genes that contribute to eye color is currently unknown, but there are a few likely candidates. These changes are known as single-nucleotide polymorphisms or SNPs. These genes are sought using associations to small changes in the genes themselves and in neighboring genes. Įye color is an inherited trait influenced by more than one gene. However, OCA2 gene polymorphism, close to proximal 5' regulatory region, explains most human eye-color variation. The genetics of eye color are so complex that almost any parent-child combination of eye colors can occur. The earlier belief that blue eye color is a simple recessive trait has been shown to be incorrect. Some of the eye-color genes include OCA2 and HERC2. So far, as many as 15 genes have been associated with eye color inheritance. The genetics and inheritance of eye color in humans is complicated. Humans and other animals have many phenotypic variations in eye color. The brightly colored eyes of many bird species result from the presence of other pigments, such as pteridines, purines, and carotenoids. Eye color is thus an instance of structural color and varies depending on the lighting conditions, especially for lighter-colored eyes. Neither blue nor green pigments are ever present in the human iris or ocular fluid. The appearance of blue, green, and hazel eyes results from the Tyndall scattering of light in the stroma, a phenomenon similar to that which accounts for the blueness of the sky called Rayleigh scattering. In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma. Myth or Fact: Blue Eyes Are More Sensitive to Light.Eye color is a polygenic phenotypic character determined by two distinct factors: the pigmentation of the eye's iris and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris. Eye Color: Unique as a Fingerprint.ĭuke University Health System. Genetics Home Reference.Īmerican Academy of Opthamology. Mutation in the PAX6 gene in twenty patients with aniridia. GPR143 mutations in Chinese patients with ocular albinism type 1. Jia X, Yuan J, Jia X, Ling S, Li S, Guo X. National Library of Medicine: Genetics Home Reference. A global view of the OCA2-HERC2 region and pigmentation. Gene-gene interactions contribute to eye colour variation in humans. Pośpiech E, Draus-Barini J, Kupiec T, Wojas-Pelc A, Branicki W. What colour are newborns’ eyes? Prevalence of iris colour in the Newborn Eye Screening Test (NEST) study. Ludwig CA, Callaway NF, Fredrick DR, Blumenkranz MS, Moshfeghi DM. Albinism: particular attention to the ocular motor system. Iris color classification scales - then and now. Novel quantitative pigmentation phenotyping enhances genetic association, epistasis, and prediction of human eye colour. National Library of Medicine: Genetics Home Library.
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