Oculocutaneous albinism 3572371 216540440 2008-06-02T02:46:34Z Arcadian 104523 ref {{Infobox_Disease | Name = {{PAGENAME}} | Image = | Caption = | DiseasesDB = | ICD10 = {{ICD10|E|70|3|e|70}} | ICD9 = {{ICD9|270.2}} | ICDO = | OMIM = | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | MeshID = D016115 | }} '''Oculocutaneous albinism''' is a form of [[albinism]] involving the [[eye]]s ("oculo-"), [[skin]] ("-cutaneous"), and according to some definitions, the [[hair]] as well.<ref name="urlOculocutaneous albinism - Genetics Home Reference">{{cite web |url=http://ghr.nlm.nih.gov/condition=oculocutaneousalbinism |title=Oculocutaneous albinism - Genetics Home Reference |format= |work= |accessdate=}}</ref> All four types are [[autosomal recessive]].<ref name="pmid17980020">{{cite journal |author=Grønskov K, Ek J, Brondum-Nielsen K |title=Oculocutaneous albinism |journal=Orphanet J Rare Dis |volume=2 |issue= |pages=43 |year=2007 |pmid=17980020 |doi=10.1186/1750-1172-2-43 |url=http://www.ojrd.com/content/2//43}}</ref> ==Types== {| class="wikitable" | '''Name''' || '''[[OMIM]]''' || '''Gene''' || '''Description''' |- | OCA1 || {{OMIM2|203100}} || [[tyrosinase|TYR]] || OCA1 is caused by an alteration of the [[tyrosinase]] gene, and can occur in two variations. The first is '''OCA1a''', and means that the organism cannot develop pigment at all. The hair is usually white (often translucent) and the skin very pale. Vision usually ranges from 20/200 to 20/400. The second is '''OCA1b''', which has several subtypes itself. Some individuals with OCA1b can tan and also develop pigment in the hair.<ref name="Facts_Albinism">[http://albinism.med.umn.edu/facts.htm "Facts about Albinism"], by Dr. Richard King et al.</ref>{{Verify source|date=July 2007}}<!--New facts were added without additional sources, implying that this reference sources both the older material and the new additions. This may or may not be the case.--> One subtype of OCA1b is called '''OCA1b TS''' (temperature sensitive), where the [[tyrosinase]] can only function below a certain temperature, which causes the body hair in cooler body regions to develop pigment (i.e. get darker). (An equivalent mutation produces the coat pattern in [[Siamese (cat)|Siamese cats]]{{Fact|date=February 2007}}.) Another variant of OCA1b, called '''Albinism, yellow mutant type''' ({{OMIM3|606952}}) is more common among the [[Amish]] than in other populations, and results in blonde hair and the eventual development of skin pigmentation during infancy, though at birth is difficult to distinguish from other types.<ref name="OMIM1">[http://www.ncbi.nlm.nih.gov.ezproxy.auckland.ac.nz/entrez/query.fcgi?CMD=search&DB=omim&term=albinism Online ''Mendelian Inheritance in Man'' Database], at [[Johns Hopkins University]] (see also [[Mendelian Inheritance in Man]] for more information about this source).</ref> <ref name="eMedicine2">[http://www.emedicine.com/oph/topic260.htm "Ocular Manifestations of Albinism"], by Dr. Mohammed O. Peracha, at [[eMedicine]], [[13 September]] [[2005]]; retrieved [[31 March]] [[2007]]</ref> About 1 in 40,000 people have some form of OCA1.<ref name="eMedicine1">[http://www.emedicine.com/derm/topic12.htm "Albinism"], by Dr. Raymond E. Boissy, Dr. James J. Nordlund, et al., at [[eMedicine]], [[22 August]] [[2005]]; retrieved [[31 March]] [[2007]]</ref><ref name="OMIM1" /> |- | OCA2 || {{OMIM2|203200}} || [[OCA2]] || The most common type of albinism, is caused by mutation of the P gene. People with OCA2 generally have more pigment and better vision than those with OCA1, but cannot tan like some with OCA1b. A little pigment can develop in freckles or moles.<ref name="Facts_Albinism"> [http://albinism.med.umn.edu/facts.htm "Facts about Albinism"], by Dr. Richard King et al. </ref> People with OCA2 usually have fair skin but not as pale as OCA1, and pale blonde to golden or reddish-blonde hair, and most commonly blue eyes. Affected people of African descent usually have a different [[phenotype]] (appearance): yellow hair, pale skin, and blue, gray or hazel eyes. About 1 in 15,000 people have OCA2.<ref name="eMedicine1" /><ref name="OMIM1" /> The gene [[MC1R]] doesn't cause OCA2, but does affect its presentation.<ref name="urlOculocutaneous albinism - Genetics Home Reference">{{cite web |url=http://ghr.nlm.nih.gov/condition=oculocutaneousalbinism |title=Oculocutaneous albinism - Genetics Home Reference |format= |work= |accessdate=}}</ref> |- | OCA3 || {{OMIM2|203290}} || [[TYRP1]] || Has only been partially researched and documented. It is caused by mutation of the tyrosinase-related protein-1 (Tyrp1) gene. Cases have been reported in Africa and New Guinea. Affected individuals typically have red hair, reddish-brown skin and blue or gray eyes. Variants may include '''rufous oculocutaneous albinism''' ('''ROCA''' or '''xanthism''') ({{OMIM3|278400}}). The incidence rate of OCA3 is unknown.<ref name="eMedicine1" /><ref name="OMIM1" /> |- | OCA4 || {{OMIM2|606574}} || [[SLC45A2]] || Is very rare outside of Japan, where OCA4 accounts for 24% of albinism cases. OCA4 can only be distinguished from OCA2 through genetic testing, and is caused by mutation of the membrane-associated transporter protein (MATP) gene.<ref name="eMedicine1" /><ref name="OMIM1" /> |- |} ==References== {{reflist|2}} {{Amino acid metabolic pathology}} [[Category:Albinism| ]]