Information about Eye Colour
Eye color is a polygenic trait and is determined primarily by the amount and type of pigments present in the eye's iris.[1][2] Humans and animals have many phenotypic variations in eye color.[3] In humans, these variations in color are attributed to varying ratios of eumelanin produced by melanocytes in the iris.[2] The brightly colored eyes of many bird species are largely determined by other pigments, such as pteridines, purines, and carotenoids.[4]
Three main elements within the iris contribute to its color: the melanin content of the iris pigment epithelium, the melanin content within the iris stroma, and the cellular density of the iris stroma.[5] In eyes of all colors, the iris pigment epithelium contains the black pigment, eumelanin.[2][5] Color variations among different irises are typically attributed to the melanin content within the iris stroma.[5] The density of cells within the stroma affects how much light is absorbed by the underlying pigment epithelium.[5]
In 2006, the molecular basis of the EYCL3 locus was resolved.[12] In a study of 3839 people, researchers reported that 74% of total variation in eye color was explained by a number of single nucleotide polymorphisms (SNPs) near the OCA2 gene (OMIM: 203200). OCA2 was previously known because, when mutated, the gene can result in a type of albinism. The recent study showed that different SNPs strongly associate with blue and green eyes as well as variations in freckling, mole counts, hair and skin tone. The authors speculate that the SNPs may be in an OCA2 regulatory sequence and thus influence the expression of the gene product, which in turn affects pigmentation.[13]
Iris color can provide a large amount of information about an individual, and a classification of various colors may be useful in documenting pathological changes or determining how a person may respond to various ocular pharmaceuticals.[14] Various classification systems have ranged from a basic "light" or "dark" description to detailed gradings employing photographic standards for comparison.[14] Others have attempted to set objective standards of color comparison.[15]
As the perception of color is dependent upon the conditions in which color is viewed (e.g. the amount and type of illumination, as well as the hue of the surrounding environment), so is the perception of eye color.[16]
Eye color exists on a continuum from the darkest shades of brown to the lightest shades of blue.[6] Seeing the need for a standardized classification system that was simple, yet detailed enough for research purposes, Seddon et. al developed a graded one based on the predominant iris color (brown, light brown, green, gray, and blue) and the amount of brown or yellow pigment present. There are 3 true colors in the eyes that determine the outward appearance; brown, yellow, and gray. How much of each color you have determines the appearance of the eye color. The color your eyes turn depends on how much of these colors are present. For example, green eyes have a lot of yellow and some brown, making them appear green. Blue eyes have a little yellow and little to no brown, making them appear blue. Gray eyes appear gray because they have a little yellow and no brown in them. Brown eyes appear brown because most of the eye contains the brown color. Brown is the most common, blue is second, and green is rarest.[17]
In humans, brown eyes contain large amounts of melanin (eumelanin) within the iris stroma which serves to absorb light, particularly at the shorter wavelengths.[5][18] Very dark brown irises may appear to be black.[19][20] People with light brown or golden irises are sometimes said to have "whiskey eyes".
Brown is very predominant[21] and, in many populations, it is (with few exceptions) the only iris color present.[22] It is least common in the countries around the Baltic Sea.
Those of mixed European and non-European ancestry generally have dark eyes, but with more variability in eye color within their families than those from more homogenous origins.[23] Inhabitants indigenous to Africa, Asia, and the Americas generally have brown eyes. Brown eyes are equally found in Europe, Oceania, and the Americas, though within some European populations they are not predominant to the same extent. Brown is considered to be the most dominant eye color in the world.
Hazel eyes are due to a combination of a Rayleigh scattering and a moderate amount of melanin in the iris' anterior border layer.[24][5] A number of studies using three-point scales have assigned "hazel" to be the medium-color between light brown and dark green.[25][26][27][28][29][30][31] This can sometimes produce a multicolored iris, i.e., an eye that is light brown near the pupil and charcoal or amber/dark green on the outer part of the iris when it is open to the elements of the sun/shined in the sunlight. Hazel is mostly found in the regions of Southern Europe, Eastern Europe and the Middle East.
There is some difficulty in defining the eye color "hazel" as it is sometimes considered to be synonymous with lightbrown and other times with dark green.[32][19][25][27][30][33] They have been described as dark green or yellowish brown,[34] or as a lighter shade of brown.[35] Hazel eyes have also been described as being equivalent to a dark green or amber color eyes/light brown.[36] In North America, "hazel" is often used to describe eyes that appear to change color, ranging from light brown to green and even blue, depending on current lighting in the environment.
Amber colored eyes are of a solid color and have a strong yellowish/golden and russet/coppery tint. This might be due to the deposition of the yellow pigment called "lipochrome" in the iris (which is also found in green and violet eyes).[37][38] Amber eyes are much more common in animals than they are in humans. They are also nicknamed "cat eyes".
The yellow eyes of some pigeons contain yellow fluorescing pigments known as pteridines.[39] The bright yellow eyes of the Great Horned Owl are thought to be due to the presence of the pteridine pigment xanthopterin within certain chromatophores (called xanthophores) located in the iris stroma.[40] In humans, yellow specks or patches are thought to be due to the pigment lipofuscin, also known as lipochrome.[24]
Green eyes are the product of moderate amounts of melanin. They are most often found among people of North and Eastern European descent, and to a slightly lesser extent, in Southern Europe, the Middle East and parts of South Asia. Deities in both Chinese and Greek mythology had green eyes, possibly because of their rarity. Only 2% of human population have green eyes. Hungary is the country with the highest percentage of green eyed people,about 20%.
Green eyes are most often depicted with red and brown hair.
Blue eyes contain low amounts of melanin within the iris stroma; longer wavelengths of light tend to be absorbed by the underlying iris pigment epithelium and shorter wavelengths are reflected and undergo Rayleigh scattering.[5] The type of melanin present is eumelanin.[18] The inheritance pattern followed by blue eyes is thought to be similar to that of a recessive trait.[7]
Blue eyes are relatively common throughout Europe and other areas with populations of European descent, such as the Americas and Oceania. While they are most common among people of Nordic and Germanic descent. There are also populations in the Middle East, Central and South Asia that have rare natural occurrences of blue eyes. Throughout the rest of the world they are rare.
Finland and Lithuania have the highest proportions of blue-eyed people; they are also very common in other countries around the Baltic Sea, such as Poland and Germany. One survey estimated that nearly 90% of Icelanders have blue or green eyes,[41] in contrast to 20% of Spaniards and Italians of the north.[42] A 2002 study found the prevalence of blue eye color among whites in the United States to be 33.8% for those born between 1936 and 1951 compared to 57.4% for those born between 1899 and 1905.[7]
As melanin production generally increases during the first few years of life (especially if exposed to the sun), the blue eyes of some babies may darken as they get older.
Gray eyes are a variant of blue eyes and are sometimes very hard to tell apart. Usually, gray eyes are considered a darker shade of blue (like blue-green), where in fact they are lighter. Under magnification, gray eyes exhibit small amounts of yellow and brown color in the iris.
A gray iris may indicate the presence of a uveitis. However, other visual signs make a uveitis obvious.
Athena, in Greek mythology, was renowned for having "sea-gray" eyes.[43]
Aniridia is a congenital condition characterized by an extremely underdeveloped iris which appears absent on superficial examination.[46]
This can also cause blindness.
Eyedrops containing a prostaglandin analogue (such as latanoprost) may result in a permanently darkened iris; these eyedrops are commonly used to treat open-angle glaucoma.[49]
Three main elements within the iris contribute to its color: the melanin content of the iris pigment epithelium, the melanin content within the iris stroma, and the cellular density of the iris stroma.[5] In eyes of all colors, the iris pigment epithelium contains the black pigment, eumelanin.[2][5] Color variations among different irises are typically attributed to the melanin content within the iris stroma.[5] The density of cells within the stroma affects how much light is absorbed by the underlying pigment epithelium.[5]
Determination of eye color
Eye color is an inherited trait influenced by more than one gene.[6][7] There are two major genes and other minor ones that account for the tremendous variation of human eye color.[8] In humans, three loci associated with eye color are currently known: EYCL1, EYCL2, and EYCL3.[9][10] These genes account for three phenotypic eye colors (brown, green, and blue) in humans.[3] Eye color usually stabilizes when an infant is around 6 months old.[11]In 2006, the molecular basis of the EYCL3 locus was resolved.[12] In a study of 3839 people, researchers reported that 74% of total variation in eye color was explained by a number of single nucleotide polymorphisms (SNPs) near the OCA2 gene (OMIM: 203200). OCA2 was previously known because, when mutated, the gene can result in a type of albinism. The recent study showed that different SNPs strongly associate with blue and green eyes as well as variations in freckling, mole counts, hair and skin tone. The authors speculate that the SNPs may be in an OCA2 regulatory sequence and thus influence the expression of the gene product, which in turn affects pigmentation.[13]
Classification of colors
)
The perception of color depends upon various factors. These are the same eyes; however, depending on the light and surrounding hues, the eye color can appear quite different.
As the perception of color is dependent upon the conditions in which color is viewed (e.g. the amount and type of illumination, as well as the hue of the surrounding environment), so is the perception of eye color.[16]
Eye color exists on a continuum from the darkest shades of brown to the lightest shades of blue.[6] Seeing the need for a standardized classification system that was simple, yet detailed enough for research purposes, Seddon et. al developed a graded one based on the predominant iris color (brown, light brown, green, gray, and blue) and the amount of brown or yellow pigment present. There are 3 true colors in the eyes that determine the outward appearance; brown, yellow, and gray. How much of each color you have determines the appearance of the eye color. The color your eyes turn depends on how much of these colors are present. For example, green eyes have a lot of yellow and some brown, making them appear green. Blue eyes have a little yellow and little to no brown, making them appear blue. Gray eyes appear gray because they have a little yellow and no brown in them. Brown eyes appear brown because most of the eye contains the brown color. Brown is the most common, blue is second, and green is rarest.[17]
Brown
)
In humans, brown eyes contain large amounts of melanin (eumelanin) within the iris stroma which serves to absorb light, particularly at the shorter wavelengths.[5][18] Very dark brown irises may appear to be black.[19][20] People with light brown or golden irises are sometimes said to have "whiskey eyes".
)
Brown is very predominant[21] and, in many populations, it is (with few exceptions) the only iris color present.[22] It is least common in the countries around the Baltic Sea.
Those of mixed European and non-European ancestry generally have dark eyes, but with more variability in eye color within their families than those from more homogenous origins.[23] Inhabitants indigenous to Africa, Asia, and the Americas generally have brown eyes. Brown eyes are equally found in Europe, Oceania, and the Americas, though within some European populations they are not predominant to the same extent. Brown is considered to be the most dominant eye color in the world.
Hazel
)
)
Hazel eyes are due to a combination of a Rayleigh scattering and a moderate amount of melanin in the iris' anterior border layer.[24][5] A number of studies using three-point scales have assigned "hazel" to be the medium-color between light brown and dark green.[25][26][27][28][29][30][31] This can sometimes produce a multicolored iris, i.e., an eye that is light brown near the pupil and charcoal or amber/dark green on the outer part of the iris when it is open to the elements of the sun/shined in the sunlight. Hazel is mostly found in the regions of Southern Europe, Eastern Europe and the Middle East.
)
There is some difficulty in defining the eye color "hazel" as it is sometimes considered to be synonymous with lightbrown and other times with dark green.[32][19][25][27][30][33] They have been described as dark green or yellowish brown,[34] or as a lighter shade of brown.[35] Hazel eyes have also been described as being equivalent to a dark green or amber color eyes/light brown.[36] In North America, "hazel" is often used to describe eyes that appear to change color, ranging from light brown to green and even blue, depending on current lighting in the environment.
Amber
)
Human amber eyes displaying the greenish yellow and russet/coppery tint
The yellow eyes of some pigeons contain yellow fluorescing pigments known as pteridines.[39] The bright yellow eyes of the Great Horned Owl are thought to be due to the presence of the pteridine pigment xanthopterin within certain chromatophores (called xanthophores) located in the iris stroma.[40] In humans, yellow specks or patches are thought to be due to the pigment lipofuscin, also known as lipochrome.[24]
Green
)
)
girl with green eyes
Blue
)
Blue eyes contain low amounts of melanin within the iris stroma; longer wavelengths of light tend to be absorbed by the underlying iris pigment epithelium and shorter wavelengths are reflected and undergo Rayleigh scattering.[5] The type of melanin present is eumelanin.[18] The inheritance pattern followed by blue eyes is thought to be similar to that of a recessive trait.[7]
Blue eyes are relatively common throughout Europe and other areas with populations of European descent, such as the Americas and Oceania. While they are most common among people of Nordic and Germanic descent. There are also populations in the Middle East, Central and South Asia that have rare natural occurrences of blue eyes. Throughout the rest of the world they are rare.
)
Finland and Lithuania have the highest proportions of blue-eyed people; they are also very common in other countries around the Baltic Sea, such as Poland and Germany. One survey estimated that nearly 90% of Icelanders have blue or green eyes,[41] in contrast to 20% of Spaniards and Italians of the north.[42] A 2002 study found the prevalence of blue eye color among whites in the United States to be 33.8% for those born between 1936 and 1951 compared to 57.4% for those born between 1899 and 1905.[7]
As melanin production generally increases during the first few years of life (especially if exposed to the sun), the blue eyes of some babies may darken as they get older.
Gray
)
Female gray eyes
)
){kind=small}
Male gray eyes
A gray iris may indicate the presence of a uveitis. However, other visual signs make a uveitis obvious.
Athena, in Greek mythology, was renowned for having "sea-gray" eyes.[43]
Violet
The appearance of violet eyes is thought to occur due to the mixing of red and blue reflections.[44] Some albinos have eyes that appear to be violet.[45]Anomalous conditions
Aniridia
)
Aniridia: Eyes wherein the irises are not present; the eyes appear to be two large pupils.
Ocular albinism and eye color
Normally, there is a thick layer of melanin on the back of the iris. Even people with the lightest blue eyes, with no melanin on the front of the iris at all, have dark brown coloration on the back of it, to prevent light from scattering around inside the eye. In those with milder forms of albinism, the color of the irises is typically blue, but can vary from blue to brown. In severe forms of albinism, there is no pigment on the back of the iris, and light from inside the eye can pass through the iris to the front. In these cases, the only color seen is the red from the hemoglobin of the blood in the capillaries of the iris. Such albinos have pink eyes, as do albino rabbits, mice, or any other animal with total lack of melanin. Transillumination defects can almost always be observed during an eye examination due to lack of iridial pigmentation.[47] The ocular albino also lacks normal amounts of melanin in the retina as well, which allows more light than normal to reflect off the retina and out of the eye. Because of this, the pupillary reflex is much brighter in the albino, and this can increase the red eye effect in photographs. Edgar Winter's eyes are an example of this trait.Heterochromia
){kind=small}
An example of heterochromia. The subject has one brown and one hazel eye.
Eye color change
Often, newborns have blue eyes, which change to green, hazel, light brown or dark brown, as they grow older. It is thought that exposure to light after birth triggers the production of melanin in the iris of the eye. By three years of age, the eyes produce and store enough melanin to indicate their natural shade. While changes in eye color of infants are more common, even in adults, eye color changes are seen, most often as a result of exposure to the sun. Sunlight triggers melanin production in the eye, as it does to the skin. People with green eyes in the winter might develop darker, more hazel eyes if they spend more time outdoors.Eyedrops containing a prostaglandin analogue (such as latanoprost) may result in a permanently darkened iris; these eyedrops are commonly used to treat open-angle glaucoma.[49]
Medical implications
Those with lighter iris color have been found to have a higher prevalence of age-related macular degeneration (ARMD) than those with darker iris color;[29] lighter eye color is also associated with an increased risk of ARMD progression.[50] An increased risk of uveal melanoma has been found in those with blue or gray iris color.[51]References
1. ^ Wielgus AR, Sarna T. "Melanin in human irides of different color and age of donors." Pigment Cell Res. 2005 Dec;18(6):454-64. PMID 16280011.
2. ^ Prota G, Hu DN, Vincensi MR, McCormick SA, Napolitano A. "Characterization of melanins in human irides and cultured uveal melanocytes from eyes of different colors." Exp Eye Res. 1998 Sep;67(3):293-9. PMID 9778410.
3. ^ Morris, PJ. "Phenotypes and Genotypes for human eye colors." Athro Limited website. Retrieved May 10, 2006.
4. ^ Oliphant LW. "Pteridines and purines as major pigments of the avian iris." Pigment Cell Res. 1987;1(2):129-31. PMID 3507666.
5. ^ Huiqiong Wang, Stephen Lin, Xiaopei Liu, Sing Bing Kang. "Separating Reflections in Human Iris Images for Illumination Estimation." Proc. IEEE International Conference on Computer Vision, 2005.
6. ^ Sturm RA, Frudakis TN. color: portals into pigmentation genes and ancestry." Trends Genet. 2004 Aug;20(8):327-32. PMID: 15262401.
7. ^ Grant MD, Lauderdale DS. "Cohort effects in a genetically determined trait: eye color among US whites." Ann Hum Biol. 2002 Nov-Dec;29(6):657-66. PMID 12573082.
8. ^ Eye color mocks easy rules
9. ^ Rebbeck TR, Kanetsky PA, Walker AH, Holmes R, Halpern AC, Schuchter LM, Elder DE, Guerry D. "P gene as an inherited biomarker of human eye color." Cancer Epidemiol Biomarkers Prev. 2002 Aug;11(8):782-4. PMID 12163334.
10. ^ "Eye color is more complex than two genes." Athro, Limited. Retrieved September 1, 2006.
11. ^ [1]
12. ^ Paul Rincon, Genetics of eye color unlocked, BBC News, 20 December, 2006.
13. ^ Duffy DL, Montgomery GW, Chen W, Zhao ZZ, Le L, James MR, Hayward NK, Martin NG, and Sturm, RA "A Three–Single-Nucleotide Polymorphism Haplotype in Intron 1 of OCA2 Explains Most Human Eye-color Variation" Am. J. Hum. Genet. 2002 80:000, 2007.
14. ^ German EJ, Hurst MA, Wood D, Gilchrist J. "A novel system for the objective classification of iris color and its correlation with response to 1% tropicamide." Ophthalmic Physiol Opt. 1998 Mar;18(2):103-10. PMID 9692029.
15. ^ Fan S, Dyer CR, Hubbard L. Quantification and Correction of Iris Color." Technical report 1495, University of Wisconsin-Madison, Dec, 2003.
16. ^ [2]
17. ^ Seddon JM, Sahagian CR, Glynn RJ, Sperduto RD, Gragoudas ES. "Evaluation of an iris color classification system." The Eye Disorders Case-Control Study Group. Invest Ophthalmol Vis Sci. 1990 Aug;31(8):1592-8. PMID: 2201662.
18. ^ Menon IA, Basu PK, Persad S, Avaria M, Felix CC, Kalyanaraman B. "Is there any difference in the photobiological properties of melanins isolated from human blue and brown eyes?" Br J Ophthalmol. 1987 Jul;71(7):549-52. PMID 2820463.
19. ^ Hammond BR Jr, Fuld K, Snodderly DM. "Iris color and macular pigment optical density." Exp Eye Res. 1996 Mar;62(3):293-7. PMID 8690039.
20. ^ Prieto JG. "Eye color in skin cancer." Int J Dermatol. 1977 Jun;16(5):406-7. PMID 873674.
21. ^ Eiberg H, Mohr J. "Assignment of genes coding for brown eye colour (BEY2) and brown hair colour (HCL3) on chromosome 15q." Eur J Hum Genet. 1996;4(4):237-41. PMID 8875191.
22. ^ [3]
23. ^ Frudakis T, Thomas M, Gaskin Z, Venkateswarlu K, Chandra KS, Ginjupalli S, Gunturi S, Natrajan S, Ponnuswamy VK, Ponnuswamy KN. Sequences associated with human iris pigmentation." Genetics. 2003 Dec;165(4):2071-83. PMID 14704187.
24. ^ Lefohn, A., Budge, B., Shirley, P., Caruso, R., and Reinhard, E. 2003. An Ocularist's Approach to Human Iris Synthesis. IEEE Comput. Graph. Appl. 23, 6 (Nov. 2003), 70-75. DOI= [4]
25. ^ Zhu G, Evans DM, Duffy DL, Montgomery GW, Medland SE, Gillespie NA, Ewen KR, Jewell M, Liew YW, Hayward NK, Sturm RA, Trent JM, Martin NG. "A genome scan for eye color in 502 twin families: most variation is due to a QTL on chromosome 15q." 1: Twin Res. 2004 Apr;7(2):197-210. PMID 15169604.
26. ^ Albert DM, Green WR, Zimbric ML, Lo C, Gangnon RE, Hope KL, Gleiser J. Hazel eyes often appear to shift in color from light brown to a medium or dark olive green. "Iris melanocyte numbers in Asian, African American, and Caucasian irides." Trans Am Ophthalmol Soc. 2003;101:217-21; discussion 221-2. PMID 14971580.
27. ^ Mitchell R, Rochtchina E, Lee A, Wang JJ, Mitchell P; Blue Mountains Eye Study. "Iris color and intraocular pressure: the Blue Mountains Eye Study." Am J Ophthalmol. 2003 Mar;135(3):384-6. PMID 12614760.
28. ^ Lindsey JD, Jones HL, Hewitt EG, Angert M, Weinreb RN. "Induction of tyrosinase gene transcription in human iris organ cultures exposed to latanoprost." Arch Ophthalmol. 2001 Jun;119(6):853-60. PMID 11405836.
29. ^ Frank RN, Puklin JE, Stock C, Canter LA. "Race, iris color, and age-related macular degeneration." Trans Am Ophthalmol Soc. 2000;98:109-15; discussion 115-7. PMID 11190014.
30. ^ Regan S, Judge HE, Gragoudas ES, Egan KM. "Iris color as a prognostic factor in ocular melanoma." Arch Ophthalmol. 1999 Jun;117(6):811-4. PMID 10369595.
31. ^ Hawkins TA, Stewart WC, McMillan TA, Gwynn DR. "Analysis of diode, argon, and Nd: YAG peripheral iridectomy in cadaver eyes." Doc Ophthalmol. 1994;87(4):367-76. PMID 7851220.
32. ^ [5]
33. ^ Naldi L, Altieri A, Imberti GL, Giordano L, Gallus S, La Vecchia C; Oncology Study Group of the Italian Group for Epidemiologic Research in Dermatology (GISED). "Cutaneous malignant melanoma in women. Phenotypic characteristics, sun exposure, and hormonal factors: a case-control study from Italy." Ann Epidemiol. 2005 Aug;15(7):545-50. PMID 16029848.
34. ^ April Holladay. "Funny — you can't hide those lightening eyes." USATODAY.com. October 8, 2004. Retrieved September 17, 2006.
35. ^ English JS, Swerdlow AJ, MacKie RM, O'Doherty CJ, Hunter JA, Clark J, Hole DJ. "Relation between phenotype and banal melanocytic naevi." Br Med J (Clin Res Ed). 1987 Jan 17;294(6565):152-4. PMID 3109545.
36. ^ Hara T. "[Increased iris pigmentation after use of latanoprost in Japanese brown eyes.]" Nippon Ganka Gakkai Zasshi. 2001 May;105(5):314-21. PMID 11406947.
37. ^ [6]
38. ^ [7]
39. ^ Oliphant LW. "Observations on the pigmentation of the pigeon iris." Pigment Cell Res. 1987;1(3):202-8. PMID 3508278.
40. ^ Oliphant LW. "Crystalline pteridines in the stromal pigment cells of the iris of the great horned owl." Cell Tissue Res. 1981;217(2):387-95. PMID 7237534.
41. ^ Rafnsson V, Hrafnkelsson J, Tulinius H, Sigurgeirsson B, Olafsson JH. "Risk factors for malignant melanoma in an Icelandic population sample." Prev Med. 2004 Aug;39(2):247-52. PMID 15226032
42. ^ [8]
43. ^ [9]
44. ^ [10]
45. ^ [11]
46. ^ [12]
47. ^ [13]
48. ^ Imesch PD, Wallow IH, Albert DM. "The color of the human eye: a review of morphologic correlates and of some conditions that affect iridial pigmentation." Surv Ophthalmol. 1997 Feb;41 Suppl 2:S117-23. PMID 9154287.
49. ^ Hejkal TW, Camras CB (1999). "Prostaglandin analogs in the treatment of glaucoma". Seminars in ophthalmology 14 (3): 114-23. DOI:10.153/SOPH01400114. PMID 10790575.
50. ^ Nicolas CM, Robman LD, Tikellis G, Dimitrov PN, Dowrick A, Guymer RH, McCarty CA. "Iris colour, ethnic origin and progression of age-related macular degeneration." Clin Experiment Ophthalmol. 2003 Dec;31(6):465-9. PMID 14641151.
51. ^ Stang A, Ahrens W, Anastassiou G, Jockel KH. "Phenotypical characteristics, lifestyle, social class and uveal melanoma." Ophthalmic Epidemiol. 2003 Dec;10(5):293-302. PMID 14566630.
2. ^ Prota G, Hu DN, Vincensi MR, McCormick SA, Napolitano A. "Characterization of melanins in human irides and cultured uveal melanocytes from eyes of different colors." Exp Eye Res. 1998 Sep;67(3):293-9. PMID 9778410.
3. ^ Morris, PJ. "Phenotypes and Genotypes for human eye colors." Athro Limited website. Retrieved May 10, 2006.
4. ^ Oliphant LW. "Pteridines and purines as major pigments of the avian iris." Pigment Cell Res. 1987;1(2):129-31. PMID 3507666.
5. ^ Huiqiong Wang, Stephen Lin, Xiaopei Liu, Sing Bing Kang. "Separating Reflections in Human Iris Images for Illumination Estimation." Proc. IEEE International Conference on Computer Vision, 2005.
6. ^ Sturm RA, Frudakis TN. color: portals into pigmentation genes and ancestry." Trends Genet. 2004 Aug;20(8):327-32. PMID: 15262401.
7. ^ Grant MD, Lauderdale DS. "Cohort effects in a genetically determined trait: eye color among US whites." Ann Hum Biol. 2002 Nov-Dec;29(6):657-66. PMID 12573082.
8. ^ Eye color mocks easy rules
9. ^ Rebbeck TR, Kanetsky PA, Walker AH, Holmes R, Halpern AC, Schuchter LM, Elder DE, Guerry D. "P gene as an inherited biomarker of human eye color." Cancer Epidemiol Biomarkers Prev. 2002 Aug;11(8):782-4. PMID 12163334.
10. ^ "Eye color is more complex than two genes." Athro, Limited. Retrieved September 1, 2006.
11. ^ [1]
12. ^ Paul Rincon, Genetics of eye color unlocked, BBC News, 20 December, 2006.
13. ^ Duffy DL, Montgomery GW, Chen W, Zhao ZZ, Le L, James MR, Hayward NK, Martin NG, and Sturm, RA "A Three–Single-Nucleotide Polymorphism Haplotype in Intron 1 of OCA2 Explains Most Human Eye-color Variation" Am. J. Hum. Genet. 2002 80:000, 2007.
14. ^ German EJ, Hurst MA, Wood D, Gilchrist J. "A novel system for the objective classification of iris color and its correlation with response to 1% tropicamide." Ophthalmic Physiol Opt. 1998 Mar;18(2):103-10. PMID 9692029.
15. ^ Fan S, Dyer CR, Hubbard L. Quantification and Correction of Iris Color." Technical report 1495, University of Wisconsin-Madison, Dec, 2003.
16. ^ [2]
17. ^ Seddon JM, Sahagian CR, Glynn RJ, Sperduto RD, Gragoudas ES. "Evaluation of an iris color classification system." The Eye Disorders Case-Control Study Group. Invest Ophthalmol Vis Sci. 1990 Aug;31(8):1592-8. PMID: 2201662.
18. ^ Menon IA, Basu PK, Persad S, Avaria M, Felix CC, Kalyanaraman B. "Is there any difference in the photobiological properties of melanins isolated from human blue and brown eyes?" Br J Ophthalmol. 1987 Jul;71(7):549-52. PMID 2820463.
19. ^ Hammond BR Jr, Fuld K, Snodderly DM. "Iris color and macular pigment optical density." Exp Eye Res. 1996 Mar;62(3):293-7. PMID 8690039.
20. ^ Prieto JG. "Eye color in skin cancer." Int J Dermatol. 1977 Jun;16(5):406-7. PMID 873674.
21. ^ Eiberg H, Mohr J. "Assignment of genes coding for brown eye colour (BEY2) and brown hair colour (HCL3) on chromosome 15q." Eur J Hum Genet. 1996;4(4):237-41. PMID 8875191.
22. ^ [3]
23. ^ Frudakis T, Thomas M, Gaskin Z, Venkateswarlu K, Chandra KS, Ginjupalli S, Gunturi S, Natrajan S, Ponnuswamy VK, Ponnuswamy KN. Sequences associated with human iris pigmentation." Genetics. 2003 Dec;165(4):2071-83. PMID 14704187.
24. ^ Lefohn, A., Budge, B., Shirley, P., Caruso, R., and Reinhard, E. 2003. An Ocularist's Approach to Human Iris Synthesis. IEEE Comput. Graph. Appl. 23, 6 (Nov. 2003), 70-75. DOI= [4]
25. ^ Zhu G, Evans DM, Duffy DL, Montgomery GW, Medland SE, Gillespie NA, Ewen KR, Jewell M, Liew YW, Hayward NK, Sturm RA, Trent JM, Martin NG. "A genome scan for eye color in 502 twin families: most variation is due to a QTL on chromosome 15q." 1: Twin Res. 2004 Apr;7(2):197-210. PMID 15169604.
26. ^ Albert DM, Green WR, Zimbric ML, Lo C, Gangnon RE, Hope KL, Gleiser J. Hazel eyes often appear to shift in color from light brown to a medium or dark olive green. "Iris melanocyte numbers in Asian, African American, and Caucasian irides." Trans Am Ophthalmol Soc. 2003;101:217-21; discussion 221-2. PMID 14971580.
27. ^ Mitchell R, Rochtchina E, Lee A, Wang JJ, Mitchell P; Blue Mountains Eye Study. "Iris color and intraocular pressure: the Blue Mountains Eye Study." Am J Ophthalmol. 2003 Mar;135(3):384-6. PMID 12614760.
28. ^ Lindsey JD, Jones HL, Hewitt EG, Angert M, Weinreb RN. "Induction of tyrosinase gene transcription in human iris organ cultures exposed to latanoprost." Arch Ophthalmol. 2001 Jun;119(6):853-60. PMID 11405836.
29. ^ Frank RN, Puklin JE, Stock C, Canter LA. "Race, iris color, and age-related macular degeneration." Trans Am Ophthalmol Soc. 2000;98:109-15; discussion 115-7. PMID 11190014.
30. ^ Regan S, Judge HE, Gragoudas ES, Egan KM. "Iris color as a prognostic factor in ocular melanoma." Arch Ophthalmol. 1999 Jun;117(6):811-4. PMID 10369595.
31. ^ Hawkins TA, Stewart WC, McMillan TA, Gwynn DR. "Analysis of diode, argon, and Nd: YAG peripheral iridectomy in cadaver eyes." Doc Ophthalmol. 1994;87(4):367-76. PMID 7851220.
32. ^ [5]
33. ^ Naldi L, Altieri A, Imberti GL, Giordano L, Gallus S, La Vecchia C; Oncology Study Group of the Italian Group for Epidemiologic Research in Dermatology (GISED). "Cutaneous malignant melanoma in women. Phenotypic characteristics, sun exposure, and hormonal factors: a case-control study from Italy." Ann Epidemiol. 2005 Aug;15(7):545-50. PMID 16029848.
34. ^ April Holladay. "Funny — you can't hide those lightening eyes." USATODAY.com. October 8, 2004. Retrieved September 17, 2006.
35. ^ English JS, Swerdlow AJ, MacKie RM, O'Doherty CJ, Hunter JA, Clark J, Hole DJ. "Relation between phenotype and banal melanocytic naevi." Br Med J (Clin Res Ed). 1987 Jan 17;294(6565):152-4. PMID 3109545.
36. ^ Hara T. "[Increased iris pigmentation after use of latanoprost in Japanese brown eyes.]" Nippon Ganka Gakkai Zasshi. 2001 May;105(5):314-21. PMID 11406947.
37. ^ [6]
38. ^ [7]
39. ^ Oliphant LW. "Observations on the pigmentation of the pigeon iris." Pigment Cell Res. 1987;1(3):202-8. PMID 3508278.
40. ^ Oliphant LW. "Crystalline pteridines in the stromal pigment cells of the iris of the great horned owl." Cell Tissue Res. 1981;217(2):387-95. PMID 7237534.
41. ^ Rafnsson V, Hrafnkelsson J, Tulinius H, Sigurgeirsson B, Olafsson JH. "Risk factors for malignant melanoma in an Icelandic population sample." Prev Med. 2004 Aug;39(2):247-52. PMID 15226032
42. ^ [8]
43. ^ [9]
44. ^ [10]
45. ^ [11]
46. ^ [12]
47. ^ [13]
48. ^ Imesch PD, Wallow IH, Albert DM. "The color of the human eye: a review of morphologic correlates and of some conditions that affect iridial pigmentation." Surv Ophthalmol. 1997 Feb;41 Suppl 2:S117-23. PMID 9154287.
49. ^ Hejkal TW, Camras CB (1999). "Prostaglandin analogs in the treatment of glaucoma". Seminars in ophthalmology 14 (3): 114-23. DOI:10.153/SOPH01400114. PMID 10790575.
50. ^ Nicolas CM, Robman LD, Tikellis G, Dimitrov PN, Dowrick A, Guymer RH, McCarty CA. "Iris colour, ethnic origin and progression of age-related macular degeneration." Clin Experiment Ophthalmol. 2003 Dec;31(6):465-9. PMID 14641151.
51. ^ Stang A, Ahrens W, Anastassiou G, Jockel KH. "Phenotypical characteristics, lifestyle, social class and uveal melanoma." Ophthalmic Epidemiol. 2003 Dec;10(5):293-302. PMID 14566630.
See also
External links
- Genetics of eye color
- Eye Color and Human Diseases
- Eye colour: portals into pigmentation genes and ancestry
- Various links on human eye color
Brown Eyes (브라운 아이즈) was a Korean musical duo, specializing in ballads. Although both members have powerful voices, they were initially disregarded because of their physical looks.
..... Click the link for more information.
..... Click the link for more information.
Polygenic inheritance, also known as quantitative or multifactorial inheritance refers to inheritance of a phenotypic characteristic (trait) that is attributable to two or more genes and their interaction with the environment.
..... Click the link for more information.
..... Click the link for more information.
pigment is a material that changes the color of light it reflects as the result of selective color absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which the material itself emits light.
..... Click the link for more information.
..... Click the link for more information.
Eyes are organs of vision that detect light. Different kinds of light-sensitive organs are found in a variety of organisms. The simplest eyes do nothing but detect whether the surroundings are light or dark, while more complex eyes can distinguish shapes and colors.
..... Click the link for more information.
..... Click the link for more information.
In anatomy, the iris (plural irises or irides) is the most visible part of the eye of vertebrates, including humans. The following describes the iris of vertebrates, not the independently evolved iris found in some cephalopods.
..... Click the link for more information.
..... Click the link for more information.
phenotype describes the total physical appearance of an organism, as opposed to its genotype. This genotype-phenotype distinction was proposed by Wilhelm Johannsen in 1911 to make clear the difference between an organism's heredity and what that heredity produces.
..... Click the link for more information.
..... Click the link for more information.
Broadly, melanin is any of the polyacetylene, polyaniline, and polypyrrole "blacks" and "browns" or their mixed copolymers. The most common form of biological melanin is a polymer of either or both of two monomer molecules: indolequinone, and dihydroxyindole carboxylic acid.
..... Click the link for more information.
..... Click the link for more information.
Melanocytes are cells located in the bottom layer (the stratum basale) of the skin's epidermis and in the middle layer of the eye (the uvea).
..... Click the link for more information.
Melanogenesis
Through a process called melanogenesis..... Click the link for more information.
Pteridine is a chemical compound composed of fused pyrimidine and pyrazine rings. A pteridine is also a group of heterocyclic compounds containing a wide variety of substitutions on this structure.
..... Click the link for more information.
..... Click the link for more information.
Purine (1) is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines make up one of the two groups of nitrogenous bases. Pyrimidines make up the other group.
..... Click the link for more information.
..... Click the link for more information.
Carotenoids are organic pigments that are naturally occurring in plants and some other photosynthetic organisms like algae, some types of fungus and some bacteria. There are over 600 known carotenoids; they are split into two classes, xanthophylls and carotenes.
..... Click the link for more information.
..... Click the link for more information.
epithelium is a tissue composed of a layer of cells. Epithelium lines both the outside (skin) and the inside cavities and lumen of bodies. The outermost layer of our skin is composed of dead stratified squamous, keratinized epithelial cells.
..... Click the link for more information.
..... Click the link for more information.
The stroma of the iris consists of fibers and cells.
The former are made up of delicate bundles of fibrous tissue; a few fibers at the circumference of the iris have a circular direction; but the majority radiate toward the pupil, forming by their interlacement, delicate
..... Click the link for more information.
The former are made up of delicate bundles of fibrous tissue; a few fibers at the circumference of the iris have a circular direction; but the majority radiate toward the pupil, forming by their interlacement, delicate
..... Click the link for more information.
locus (plural loci) is a fixed position on a chromosome, such as the position of a gene or a biomarker (genetic marker). A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map.
..... Click the link for more information.
..... Click the link for more information.
phenotype describes the total physical appearance of an organism, as opposed to its genotype. This genotype-phenotype distinction was proposed by Wilhelm Johannsen in 1911 to make clear the difference between an organism's heredity and what that heredity produces.
..... Click the link for more information.
..... Click the link for more information.
single nucleotide polymorphism, or SNP (pronounced snip), is a DNA sequence variation occurring when a single nucleotide - A, T, C, or G - in the genome (or other shared sequence) differs between members of a species (or between paired chromosomes in an individual).
..... Click the link for more information.
..... Click the link for more information.
Albinism
Classification & external resources
Albinistic boy
ICD-10 E 70.3
ICD-9 270.2
OMIM 203100 103470 , 203200 , 203280 ,
..... Click the link for more information.
Classification & external resources
Albinistic boy
ICD-10 E 70.3
ICD-9 270.2
OMIM 203100 103470 , 203200 , 203280 ,
..... Click the link for more information.
MeSH D008548 Freckles are small colored spots of melanin on the exposed skin or membrane of people with complexions fair enough for them to be visible.
Having freckles is genetic and is related to the presence of the melanocortin-1 receptor MC1R gene variant, which is
..... Click the link for more information.
Having freckles is genetic and is related to the presence of the melanocortin-1 receptor MC1R gene variant, which is
..... Click the link for more information.
MeSH D009508 A mole, technically known as a melanocytic naevus, is a small, dark spot on human skin. According to the American Academy of Dermatology, the majority of moles appear during the first two decades of a person’s life while about one in every 100 babies are
..... Click the link for more information.
..... Click the link for more information.
This article or section needs copy editing for grammar, style, cohesion, tone and/or spelling.
You can assist by [ editing it] now. A how-to guide is available, as is general .
This article has been tagged since June 2007.
..... Click the link for more information.
You can assist by [ editing it] now. A how-to guide is available, as is general .
This article has been tagged since June 2007.
..... Click the link for more information.
Human skin color can range from very dark brown to nearly colorless (appearing pinkish white due to the blood in the skin) in different people. Skin color is determined by the amount and type of the pigment melanin in the skin. On average, women have slightly lighter skin than men.
..... Click the link for more information.
..... Click the link for more information.
A regulatory sequence (also called regulatory region or ~ element) is a promoter, enhancer or other segment of DNA where regulatory proteins such as transcription factors bind preferentially. They control gene expression and thus protein expression.
..... Click the link for more information.
..... Click the link for more information.
Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect or emit. The nervous system derives color by comparing the responses to light from the several types of cone photoreceptors in the eye.
..... Click the link for more information.
..... Click the link for more information.
Baltic Sea is located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and the Little Belt.
..... Click the link for more information.
..... Click the link for more information.
Africa is the world's second-largest and second most-populous continent, after Asia. At about 30,221,532 km² (11,668,545 sq mi) including adjacent islands, it covers 6% of the Earth's total surface area, and 20.4% of the total land area.
..... Click the link for more information.
..... Click the link for more information.
Asia is the world's largest and most populous continent. It covers 8.6% of the Earth's total surface area (or 29.4% of its land area) and, with almost 4 billion people, it contains more than 60% of the world's current human population.
..... Click the link for more information.
..... Click the link for more information.
Americas are the lands of the Western hemisphere or New World consisting of the continents of North America[1] and South America with their associated islands and regions. The Americas cover 8.3% of the Earth's total surface area (28.
..... Click the link for more information.
..... Click the link for more information.
Europe is one of the seven traditional continents of the Earth. Physically and geologically, Europe is the westernmost peninsula of Eurasia, west of Asia. Europe is bounded to the north by the Arctic Ocean, to the west by the Atlantic Ocean, to the south by the Mediterranean Sea,
..... Click the link for more information.
..... Click the link for more information.
Oceania (sometimes Oceanica) is a geographical, often geopolitical, region consisting of numerous lands—mostly islands in the Pacific Ocean and vicinity. The exact scope of Oceania is defined variously, with interpretations often including Australia, New Zealand, New
..... Click the link for more information.
..... Click the link for more information.
Americas are the lands of the Western hemisphere or New World consisting of the continents of North America[1] and South America with their associated islands and regions. The Americas cover 8.3% of the Earth's total surface area (28.
..... Click the link for more information.
..... Click the link for more information.
This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.
Herod_Archelaus
