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The SLC24A5 gene's derived Ala111Thr allele (rs1426654 [78]) has been shown to be a major factor in light skin pigmentation and is common in Western Eurasia. [68] Recent studies have found that the variant represents as much as 25–40% of the average skin tone difference between Europeans and West Africans.
Light skin is a human skin color that has a low level of eumelanin pigmentation as an adaptation to environments of low UV radiation. [ 1 ] [ 2 ] Due to migrations of people in recent centuries, light-skinned populations today are found all over the world.
Global frequency distribution of the SLC24A5 gene's ancestral Ala111 allele (yellow) and its derived Ala111Thr allele (blue). SLC24A5 appears to have played a key role in the evolution of light skin in humans of European ancestry. The gene's function in pigmentation was discovered in zebrafish as a result of the positional cloning of the gene ...
Melanin is also important in mammalian pigmentation. [40] The coat pattern of mammals is determined by the agouti gene which regulates the distribution of melanin. [41] [42] The mechanisms of the gene have been extensively studied in mice to provide an insight into the diversity of mammalian coat patterns. [43]
There is evidence that as many as 16 different genes could be responsible for eye color in humans; however, the main two genes associated with eye color variation are OCA2 and HERC2, and both are localized in chromosome 15. [10] The gene OCA2 (OMIM: 203200), when in a variant form, causes the pink eye color and hypopigmentation common in human ...
Agouti-signaling protein is a protein that in humans is encoded by the ASIP gene. [5] [6] It is responsible for the distribution of melanin pigment in mammals.[7] [8] Agouti interacts with the melanocortin 1 receptor to determine whether the melanocyte (pigment cell) produces phaeomelanin (a red to yellow pigment), or eumelanin (a brown to black pigment). [9]
Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or one blue eye and one brown eye), a white forelock or patches of light skin.
Mutations in the gene have also been identified as the cause of human Type IV oculocutaneous albinism. [14] SLC45A2 is the so-called cream gene responsible in horses for buckskin, palomino and cremello coloration, while a mutation in this gene underlies the white tiger variant. [ 15 ]