Overview
Gene (OMIM no.) |
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Function of gene/protein |
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Clinical phenotype (with OMIM phenotype no.) | |
Inheritance |
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Ocular features | The ocular phenotype and visual function are highly variable among individuals affected by OCA2. They may have some/all of the following features:
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Signs for CSNB |
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Systemic features |
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Key investigations |
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Molecular diagnosis | Next generation sequencing
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Management | |
Therapies under research | |
Further information |
Additional information
Type 2 oculocutaneous albinism (OCA2) accounts for 30% of albinism cases worldwide.[9] It is very common among Africans or those of African origin, with an estimated prevalence ranging from around 1 in 10,000 cases among African Americans in the United States to around 1 in 3,900 cases in certain populations in sub-Saharan Africa. This is mainly due to the high frequency of an intragenic 2.7 kilobase deletion which results in the removal of exon 7 in the OCA2 gene in Africa. [10,11]
References
- Lee ST, Nicholls RD, Jong MT, Fukai K, Spritz RA. Organization and sequence of the human P gene and identification of a new family of transport proteins. Genomics 1995;26(2):354-363.
- Lee ST, Nicholls RD, Bundey S, Laxova R, Musarella M, Spritz RA. Mutations of the P gene in oculocutaneous albinism, ocular albinism, and Prader-Willi syndrome plus albinism. N Engl J Med. 1994;330(8):529-534.
- Rosemblat S, Durham-Pierre D, Gardner JM, Nakatsu Y, Brilliant MH, Orlow SJ. Identification of a melanosomal membrane protein encoded by the pink-eyed dilution (type II oculocutaneous albinism) gene. Proc Natl Acad Sci U S A. 1994;91(25):12071-12075.
- Wiriyasermkul P, Moriyama S, Nagamori S. Membrane transport proteins in melanosomes: Regulation of ions for pigmentation. Biochim Biophys Acta Biomembr. 2020;1862(12):183318.
- Rinchik EM, Bultman SJ, Horsthemke B, et al. A gene for the mouse pink-eyed dilution locus and for human type II oculocutaneous albinism. Nature. 1993;361(6407):72-76.
- Federico JR, Krishnamurthy K. Albinism. In: StatPearls. Treasure Island (FL): StatPearls Publishing; August 27, 2021.
- King RA, Willaert RK, Schmidt RM, et al. MC1R mutations modify the classic phenotype of oculocutaneous albinism type 2 (OCA2). Am J Hum Genet. 2003;73(3):638-645.
- Chan HW, Schiff ER, Tailor VK, et al. Prospective Study of the Phenotypic and Mutational Spectrum of Ocular Albinism and Oculocutaneous Albinism. Genes (Basel). 2021;12(4):508.
- Simeonov DR, Wang X, Wang C, et al. DNA variations in oculocutaneous albinism: an updated mutation list and current outstanding issues in molecular diagnostics. Hum Mutat. 2013;34(6):827-835.
- Durham-Pierre D, Gardner JM, Nakatsu Y, et al. African origin of an intragenic deletion of the human P gene in tyrosinase positive oculocutaneous albinism. Nat Genet. 1994;7(2):176-179.
- Stevens G, Ramsay M, Jenkins T. Oculocutaneous albinism (OCA2) in sub-Saharan Africa: distribution of the common 2.7-kb P gene deletion mutation. Hum Genet. 1997;99(4):523-527.