Oculocutaneous albinism is a form of albinism involving the eyes (oculo-), the skin (-cutaneous), and the hair.[1] Overall, an estimated 1 in 20,000 people worldwide are born with oculocutaneous albinism.[1] OCA is caused by mutations in several genes that control the synthesis of melanin within the melanocytes.[2] Seven types of oculocutaneous albinism have been described, all caused by a disruption of melanin synthesis and all autosomal recessive disorders.[3][4][5]: 864 Oculocutaneous albinism is also found in non-human animals.
OCA1 is caused by mutations of the tyrosinase gene, and can occur in two variations. The first is OCA1a, and means that the organism cannot synthesize melanin whatsoever.[6] The hair is usually white (often translucent) and the skin is very pale. Vision usually ranges from 20/200 to 20/400. The second is OCA1b, which has several subtypes itself.[7][8] Some individuals with OCA1b can tan and also develop pigment in the hair.[9] 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 points pattern in Siamese cats.[10]) Another variant of OCA1b, called Albinism, yellow mutant type, is more common among the Amish than in other populations. It results in blonde hair and the eventual development of skin pigmentation during infancy, though at birth is difficult to distinguish from other types.[7][11] About 1 in 40,000 people have some form of OCA1.[12]
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.[9] People with OCA2 usually have fair skin, but are often not as pale as OCA1. They have pale blonde to golden, strawberry blonde, or even brown 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.[13][12] The gene MC1R does not cause OCA2, but does affect its presentation.[1]
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). The incidence rate of OCA3 is unknown.[14][12]
Is very rare outside 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 this membrane-associated transporter protein (MATP) gene.[15][12] Several German patients were identified in 2004.[16]
OCA5
615312
OCA5 was identified in a Pakistani family with "golden-colored hair, white skin, nystagmus, photophobia, fovealhypoplasia, and impaired visual acuity, regardless of their sex and age". Genetic analysis localized the defect to human chromosome region 4q24, but failed to identify a candidate gene.[17][18]
One of the rarest forms of OCA, OCA6 was detected in Chinese individuals but is not thought to be limited to this ethnicity. It is heterogeneous in its effect of hair color, and results from mutations in the SLC24A5 gene, a membrane transporter that plays a role in pigmentation in a range of vertebrate species.[18][19]
OCA7
615179
C10orf11
OCA7 was originally characterized in a family from the Faroe Islands, but was subsequently identified in a Lithuanian patient. It is characterized by lighter pigmentation and significant effects on the eye, including decreased visual acuity and misrouting of neuronal tracks through the optic chiasm. It is due to mutation of a gene of unknown function, C10orf11 (11th uncharacterized open reading frame on chromosome 10, OMIM: 614537).[18][20]
^Mendez, Rodrigo; Iqbal, Sumaiya; Vishnopolska, Sebastián; Martinez, Cinthia; Dibner, Glenda; Aliano, Rocio; Zaiat, Jonathan; Biagioli, Germán; Fernandez, Cecilia; Turjanski, Adrian; Campbell, Arthur J.; Mercado, Graciela; Marti, Marcelo A. (18 February 2021). "Oculocutaneous albinism type 1B associated with a functionally significant tyrosinase gene polymorphism detected with Whole Exome Sequencing". Ophthalmic Genetics. 42 (3): 291–295. doi:10.1080/13816810.2021.1888129. ISSN 1381-6810. PMID 33599182. S2CID 231953047.
^ abKing RA, Summers G, Haefemeyer JW, LeRoy B (2009). . Archived from the original on 15 February 2009.
^Giebel LB, Tripathi RK, King RA, Spritz RA (March 1991). "A tyrosinase gene missense mutation in temperature-sensitive type I oculocutaneous albinism. A human homologue to the Siamese cat and the Himalayan mouse". The Journal of Clinical Investigation. 87 (3): 1119–1122. doi:10.1172/JCI115075. PMC329910. PMID 1900309.
^Peracha MO, Eliott D, Garcia-Valenzuela E (13 September 2005). Gordon K 3rd, Talavera F, Rowsey JJ, Brown LL, Roy H Sr (eds.). . eMedicine. WebMD. Archived from the original on 9 June 2007. Retrieved 31 March 2007.
^ abcdBoissy RE, Nordlund JJ (22 August 2005). Ortonne JP, Vinson RP, Perry V, Gelfand JM, James WD (eds.). . eMedicine. WebMD. Archived from the original on 8 June 2007. Retrieved 31 March 2007.
^Rundshagen U, Zühlke C, Opitz S, Schwinger E, Käsmann-Kellner B (February 2004). "Mutations in the MATP gene in five German patients affected by oculocutaneous albinism type 4". Human Mutation. 23 (2): 106–110. doi:10.1002/humu.10311. PMID 14722913. S2CID 40612241.
^ abcMontoliu L, Grønskov K, Wei A, Martínez-García M, Fernández A, Arveiler B, Morice-Picard F, Riazuddin S, Suzuki T, Ahmed Z, Rosenberg T, Li W (January 2014). "Increasing the complexity: new genes and new types of albinism". Pigment Cell & Melanoma Research. 27 (1): 11–18. doi:10.1111/pcmr.12167. PMID 24066960.
Oculocutaneous albinism information at RareDiseases.org
NCBI Genetic Testing Registry
April 14, 2024
oculocutaneous, albinism, form, albinism, involving, eyes, oculo, skin, cutaneous, hair, overall, estimated, people, worldwide, born, with, oculocutaneous, albinism, caused, mutations, several, genes, that, control, synthesis, melanin, within, melanocytes, sev. Oculocutaneous albinism is a form of albinism involving the eyes oculo the skin cutaneous and the hair 1 Overall an estimated 1 in 20 000 people worldwide are born with oculocutaneous albinism 1 OCA is caused by mutations in several genes that control the synthesis of melanin within the melanocytes 2 Seven types of oculocutaneous albinism have been described all caused by a disruption of melanin synthesis and all autosomal recessive disorders 3 4 5 864 Oculocutaneous albinism is also found in non human animals Oculocutaneous albinismOther namesOCASpecialtyOphthalmology dermatology Contents 1 Types 2 See also 3 References 4 External linksTypes editThe following types of oculocutaneous albinism have been identified in humans Name OMIM Gene DescriptionOCA1 203100 606952 TYR OCA1 is caused by mutations of the tyrosinase gene and can occur in two variations The first is OCA1a and means that the organism cannot synthesize melanin whatsoever 6 The hair is usually white often translucent and the skin is very pale Vision usually ranges from 20 200 to 20 400 The second is OCA1b which has several subtypes itself 7 8 Some individuals with OCA1b can tan and also develop pigment in the hair 9 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 points pattern in Siamese cats 10 Another variant of OCA1b called Albinism yellow mutant type is more common among the Amish than in other populations It results in blonde hair and the eventual development of skin pigmentation during infancy though at birth is difficult to distinguish from other types 7 11 About 1 in 40 000 people have some form of OCA1 12 OCA2 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 9 People with OCA2 usually have fair skin but are often not as pale as OCA1 They have pale blonde to golden strawberry blonde or even brown 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 13 12 The gene MC1R does not cause OCA2 but does affect its presentation 1 OCA3 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 The incidence rate of OCA3 is unknown 14 12 OCA4 606574 SLC45A2 Is very rare outside 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 this membrane associated transporter protein MATP gene 15 12 Several German patients were identified in 2004 16 OCA5 615312 OCA5 was identified in a Pakistani family with golden colored hair white skin nystagmus photophobia foveal hypoplasia and impaired visual acuity regardless of their sex and age Genetic analysis localized the defect to human chromosome region 4q24 but failed to identify a candidate gene 17 18 OCA6 113750 SLC24A5 One of the rarest forms of OCA OCA6 was detected in Chinese individuals but is not thought to be limited to this ethnicity It is heterogeneous in its effect of hair color and results from mutations in the SLC24A5 gene a membrane transporter that plays a role in pigmentation in a range of vertebrate species 18 19 OCA7 615179 C10orf11 OCA7 was originally characterized in a family from the Faroe Islands but was subsequently identified in a Lithuanian patient It is characterized by lighter pigmentation and significant effects on the eye including decreased visual acuity and misrouting of neuronal tracks through the optic chiasm It is due to mutation of a gene of unknown function C10orf11 11th uncharacterized open reading frame on chromosome 10 OMIM 614537 18 20 See also editPiebaldism List of skin conditions List of cutaneous conditions associated with increased risk of nonmelanoma skin cancerReferences edit a b c Oculocutaneous albinism Genetics Home Reference U S National Library of Medicine Retrieved 5 August 2020 Orphanet Oculocutaneous albinism Orphanet OMIM Entry 615179 ALBINISM OCULOCUTANEOUS TYPE VII OCA7 Online Mendelian Inheritance in Man Johns Hopkins University Retrieved 16 June 2020 Gronskov K Ek J Brondum Nielsen K 2007 Oculocutaneous albinism Orphanet Journal of Rare Diseases 2 Article 43 doi 10 1186 1750 1172 2 43 PMC 2211462 PMID 17980020 James WD Berger T Elston DM 2005 Andrews Diseases of the Skin Clinical Dermatology 10 ed Saunders ISBN 0 7216 2921 0 OMIM Entry 203100 ALBINISM OCULOCUTANEOUS TYPE IA OCA1A Mendelian Inheritance in Man Johns Hopkins University Retrieved 5 August 2020 a b OMIM Entry 606952 ALBINISM OCULOCUTANEOUS TYPE IB OCA1B Mendelian Inheritance in Man Johns Hopkins University Retrieved 5 August 2020 Mendez Rodrigo Iqbal Sumaiya Vishnopolska Sebastian Martinez Cinthia Dibner Glenda Aliano Rocio Zaiat Jonathan Biagioli German Fernandez Cecilia Turjanski Adrian Campbell Arthur J Mercado Graciela Marti Marcelo A 18 February 2021 Oculocutaneous albinism type 1B associated with a functionally significant tyrosinase gene polymorphism detected with Whole Exome Sequencing Ophthalmic Genetics 42 3 291 295 doi 10 1080 13816810 2021 1888129 ISSN 1381 6810 PMID 33599182 S2CID 231953047 a b King RA Summers G Haefemeyer JW LeRoy B 2009 Facts about Albinism Archived from the original on 15 February 2009 Giebel LB Tripathi RK King RA Spritz RA March 1991 A tyrosinase gene missense mutation in temperature sensitive type I oculocutaneous albinism A human homologue to the Siamese cat and the Himalayan mouse The Journal of Clinical Investigation 87 3 1119 1122 doi 10 1172 JCI115075 PMC 329910 PMID 1900309 Peracha MO Eliott D Garcia Valenzuela E 13 September 2005 Gordon K 3rd Talavera F Rowsey JJ Brown LL Roy H Sr eds Ocular Manifestations of Albinism eMedicine WebMD Archived from the original on 9 June 2007 Retrieved 31 March 2007 a b c d Boissy RE Nordlund JJ 22 August 2005 Ortonne JP Vinson RP Perry V Gelfand JM James WD eds Albinism eMedicine WebMD Archived from the original on 8 June 2007 Retrieved 31 March 2007 OMIM Entry 203200 ALBINISM OCULOCUTANEOUS TYPE II OCA2 Mendelian Inheritance in Man Johns Hopkins University Retrieved 5 August 2020 OMIM Entry 203290 ALBINISM OCULOCUTANEOUS TYPE III OCA3 Mendelian Inheritance in Man Johns Hopkins University Retrieved 5 August 2020 OMIM Entry 606574 ALBINISM OCULOCUTANEOUS TYPE IV OCA4 Mendelian Inheritance in Man Johns Hopkins University Retrieved 5 August 2020 Rundshagen U Zuhlke C Opitz S Schwinger E Kasmann Kellner B February 2004 Mutations in the MATP gene in five German patients affected by oculocutaneous albinism type 4 Human Mutation 23 2 106 110 doi 10 1002 humu 10311 PMID 14722913 S2CID 40612241 OMIM Entry 615312 ALBINISM OCULOCUTANEOUS TYPE V OCA5 Mendelian Inheritance in Man Johns Hopkins University Retrieved 5 August 2020 a b c Montoliu L Gronskov K Wei A Martinez Garcia M Fernandez A Arveiler B Morice Picard F Riazuddin S Suzuki T Ahmed Z Rosenberg T Li W January 2014 Increasing the complexity new genes and new types of albinism Pigment Cell amp Melanoma Research 27 1 11 18 doi 10 1111 pcmr 12167 PMID 24066960 OMIM Entry 113750 ALBINISM OCULOCUTANEOUS TYPE VI OCA6 Mendelian Inheritance in Man Johns Hopkins University Retrieved 5 August 2020 OMIM Entry 615179 ALBINISM OCULOCUTANEOUS TYPE VII OCA7 Mendelian Inheritance in Man Johns Hopkins University Retrieved 5 August 2020 External links editOculocutaneous albinism information at RareDiseases org NCBI Genetic Testing Registry Retrieved from https en wikipedia org w index php title Oculocutaneous albinism amp oldid 1202815642, wikipedia, wiki, book, books, library,
