- Albinism
- Partial or total lack of the pigment melanin in the skin, hair and iris. The word albino is Portuguese and comes from the Latin albus for white.
* * *A group of inherited (usually autosomal recessive) disorders with deficiency or absence of pigment in the skin, hair, and eyes, or eyes only, due to an abnormality in production of melanin. See ocular a., piebaldism. [albino + ism]- cutaneous a. [MIM*126070] SYN: piebaldism.- Forsius-Eriksson a. SYN: ocular a. 2.- Nettleshop-Falls a. SYN: ocular a. 1.- ocular a. [MIM*300650 & *300700] absence of pigment chiefly in the iris, choroid, and retinal epithelium.- ocular a. 1 [MIM*300500] type of ocular a. characterized by depigmentation of the fundus and prominent choroidal vessels, nystagmus, and titubation; vision is usually impaired; caused by mutation in the OA1 gene on chromosome Xp; X-linked inheritance. SYN: Nettleshop-Falls a..- ocular a. 2 [MIM*300600] type of ocular a. characterized by hypoplasia of the fovea, marked impairment of vision, nystagmus, myopia, astigmatism, and protanomalous color blindness, in addition to a. of the fundus. SYN: Åland Island a., Forsius-Eriksson a..- ocular a. 3 [MIM*203310] type of ocular a. characterized by impaired vision, translucent irides, congenital nystagmus, photophobia, albinotic fundi with hyperplasia of the fovea, and strabismus; caused by mutation in the pinkeye gene (P) on 6q; autosomal recessive inheritance.- ocular a. with sensorineural deafness [MIM*103470] Waardenburg syndrome, type II.. See Waardenburg syndrome.- oculocutaneous a. a disorder characterized by deficiency of pigment in skin, hair, and eyes, photophobia, nystagmus, and decreased visual acuity; there are two groups: tyrosinase-negative [MIM*203100] in which there is absence of tyrosinase, and tyrosinase-positive [MIM*203200] in which normal tyrosinase cannot enter pigment cells; the compound heterozygote is normal so the two forms are not allelic. There are several forms of autosomal recessive inheritance : type IA is characterized by absence of tyrosinase with life-long complete absence of melanin, marked photophobia, and nystagmus, caused by mutation in the tyrosinase gene (TYR) on chromosome 11q. Type II has normal tyrosinase activity and is the most common; hair darkens and nevi and freckles develop; caused by mutation in the oculocutaneous abinism gene (OCA2) on 15q. Type III is characterized by absent tyrosinase but pigmentation of the iris in the first decade; caused by mutation in the tyrosine-related protein-1gene (TYRP1) on 9p. Type IV is found in Africans with normal tyrosinase and type V is associated with red hair. Type VI is synonymous to Hermansky-Pudlak syndrome [MIM*203300], with low to absent tyrosinase and hemorrhage due to platelet deficiency, caused by mutation in the Hermansky-Pudlak gene (HPS) on 10q.
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al·bi·nism 'al-bə-.niz-əm, al-'bī- n the condition of an albinoal·bi·nis·tic .al-bə-'nis-tik adj* * *
n.the inherited absence of pigmentation in the skin, hair, and eyes, resulting in white hair and pink skin and eyes. The pink colour is produced by blood in underlying blood vessels, which are normally masked by pigment. Ocular signs are reduced visual acuity, sensitivity to light (see photophobia), and involuntary side-to-side eye movements.* * *
al·bi·nism (alґbĭ-niz-əm) [Port. albino, from L. albus white + -ism] a group of genetic abnormalities of melanin synthesis causing hypomelanosis or amelanosis of the eyes and skin. It may affect the eyes only (ocular albinism) or eyes, hair, and skin (oculocutaneous albinism). albinotic adj
Albinism; the fingers are those of a normally pigmented adult.
Medical dictionary. 2011.
