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Genetics, sun exposure, and some drugs are the three main factors that contribute to skin pigmentation. [4] The most frequent cause of low melanin concentration (hypopigmentation) is prior skin trauma, which includes skin lesions including blisters, burns, infections, exposure to chemicals, and other wounds. The skin will appear paler than the ...
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 ...
Melanism is the congenital excess of melanin in an organism resulting in dark pigment. Pseudomelanism, also called abundism, is another variant of pigmentation, identifiable by dark spots or enlarged stripes, which cover a large part of the body of the animal, making it appear melanistic. [2]
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 ]
Piebaldism refers to the absence of mature melanin-forming cells (melanocytes) in certain areas of the skin and hair. It is a rare autosomal dominant disorder of melanocyte development. [ 2 ] : 867 Common characteristics include a congenital white forelock , scattered normal pigmented and hypopigmented macules and a triangular shaped ...
Pigmentation including tanning is under hormonal control, including the MSH and ACTH peptides that are produced from the precursor proopiomelanocortin. Vitiligo is a skin disease where people lack melanin in certain areas in the skin. People with oculocutaneous albinism typically have a very low level of melanin production.
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 tyrosine. Depending on the mutation involved, this conversion is reduced or ...
The discolored skin is caused by excessive deposits of melanin (normal skin pigment). Most newborns with IP will develop discolored skin within the first two weeks. The pigmentation involves the trunk and extremities, is slate-grey, blue or brown, and is distributed in irregular marbled or wavy lines. The discoloration sometimes fades with age.