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This is an accepted version of this page This is the latest accepted revision, reviewed on 28 January 2025. "Skin pigmentation" redirects here. For animal skin pigmentation, see Biological pigment. Extended Coloured family from South Africa showing some spectrum of human skin coloration Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among ...
Pigmentation disorders are disturbances of human skin color. [1] There may be a loss or reduction, which may be related to loss of melanocytes or the inability of melanocytes to produce melanin or transport melanosomes correctly. [1] Most pigmentation disorders involve the underproduction or overproduction of melanin. [2] [3]
[42] [43] Populations with light skin pigmentation evolved in climates of little sunlight. Light skin pigmentation protects against vitamin D deficiency. It is known that dark-skinned people who have moved to climates of limited sunlight can develop vitamin D-related conditions such as rickets, and different forms of cancer. [3] [44]
It is an autosomal recessive disorder characterized by a congenital reduction or absence of melanin pigment in the skin, hair, and eyes. The estimated frequency of OCA2 among African-Americans is 1 in 10,000, which contrasts with a frequency of 1 in 36,000 in white Americans. [ 55 ]
The pigment-producing cells that contribute to the yellow spots of some sub-species are called xanthophores. [30] It appears that the fully-black phenotypes do not ever develop these xanthophores. [31] Alpine salamanders produce a toxin from their skin, and both fully melanistic, black salamanders and spotted individuals produce the compound. [32]
A common example of pleiotropy is the human disease phenylketonuria (PKU). This disease causes mental retardation and reduced hair and skin pigmentation, and can be caused by any of a large number of mutations in the single gene on chromosome 12 that codes for the enzyme phenylalanine hydroxylase, which converts the amino acid phenylalanine to ...
The answer rests in something called melanocytes -- or the cells inside a zebra that produce the black pigment of their skin. Case solved! READ MORE: Goat on the loose quickly captured, but steals ...
It is widely supposed that light skin pigmentation developed due to the importance of maintaining vitamin D3 production in the skin. [24] Strong selective pressure would be expected for the evolution of light skin in areas of low UV radiation. [15] Evolutionary model of human pigmentation in three continental populations.