DefinitionThis section has been translated automatically.
Group of genetically different, almost exclusively autosomal-recessive inherited metabolic diseases characterized by diffuse hypopigmentation in skin, hair and eyes; caused by partial or complete absence of melanin in the melanocytes The number of epidermal and follicular melanocytes is normal.
ClassificationThis section has been translated automatically.
7 types are differentiated based on molecular differences:
- OCA 1 (Tyrosinase-negative OCA): Based on reduced or no tyrosinase activity; about 80 mutations in the tyrosinase gene (TYR) have been described. OCA 1 is also known as yellow albinism.
- OCA 2 (tyrosinase-positive OCA): Based on mutations in the P gene; the role of the P protein is still unclear; regulation of the pH in the melanosomes? OCA 2 is also known as brown albinism or brown African albinism.
- OCA 3 (OMIM 203290)- Red albinism: Caused by mutations in the tyrosinase-related protein gene (TYRP1 gene; Tyrp1 protein is a melanocyte-specific gene product involved in eumelanin synthesis).
- OCA 4 (OMIM 606574): Caused by mutations of a membrane-associated transporter protein (MATP) gene encoding a transport protein for melanin precursors. Common in Korea and Japan.
- OCA 5: OCA 5 has been described in a Pakistani family (white skin, golden hair and eye symptoms). The gene is still unknown; it has been assigned to chromosome 4q24, a gene locus that probably codes for lysosomal proteins.
- OCA 6-7: Like OCA 4, OCA 6 is a mutation of a transporter protein (chromosome 15q21.1). In OCA 7 a mutation was found in the gene " C10orf11" located on chromosome 10q 22.2-22.3 which codes for a protein that is important for melanocyte differentiation. Further entities are expected in the future.
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Occurrence/EpidemiologyThis section has been translated automatically.
Most common inherited disease with diffuse hypomelanosis of the skin. The prevalence is estimated at 1:17,000 - 1:20,000 inhabitants; for some African strains it is 1:1,500 inhabitants.
For the tyrosine negative subtype OCA1 (affects 40% of all forms of albnism) the estimated prevalence in the European population is 1:40,000.
The tyrosine-positive subtype OCA2 (affects 50% of all forms of albnism worldwide) occurs predominantly in the African population. In South Africa and Tanzania, the prevalence is 1:1,400 to 1:10,000 inhabitants (cited in Kubash A 2017)
EtiopathogenesisThis section has been translated automatically.
All types of oculocutaneous albinism (OCA) are based on an autosomal recessive inheritance mechanism, except for a few families with autosomal dominant OCA. The disease is caused by mutations that directly affect the tyrosine singing TYR, or genes of proteins that regulate the processing of the copper-containing enzyme tyrosinase and the biosynthesis of melanin in melanosomes and the secretion of mature melanosomes into the epidermis (cited in Kubasch A et al. 2017).
TherapyThis section has been translated automatically.
Despite various preclinical approaches (e.g. tyrosinase gene transfer, etc.), the only therapeutic options remaining are strict physical and chemical sun protection. Regular dermatological check-ups are necessary (incidences of basal cell carcinoma and squamous cell carcinoma are significantly increased, but not of malignant melanoma).
Note(s)This section has been translated automatically.
LiteratureThis section has been translated automatically.
- Baxter LL, Pavan WJ (2002) The oculocutaneous albinism type IV gene Matp is a new marker of pigment cell precursors during mouse embryonic development. Mech Dev 116: 209-212
- Kamaraj B et al(2014) Mutational analysis of oculocutaneous albinism: a compact review. Biomed Res Int doi: 10.1155/2014/905472.
- King RA et al (2003) Tyrosinase gene mutations in oculocutaneous albinism 1 (OCA1): definition of the phenotype. Hum Genet 113: 502-513
- Kubasch A et al (2017) Oculocutaneous and ocular albinism. Dermatologist 68: 867-875
- King RA et al (2003) MC1R mutations modify the classic phenotype of oculocutaneous albinism type 2 (OCA2). At J Hum Genet 73: 638-645
- Nakamura E et al (2002) A novel mutation of the tyrosinase gene causing oculocutaneous albinism type 1 (OCA1). J Dermatol Sci 28: 102-105
- Oetting WS et al (2003) Oculocutaneous albinism type 1: the last 100 years. Pigment Cell Res 16: 307-311
- Okulicz JF et al (2003) Oculocutaneous albinism. J Eur Acad Dermatol Venereol 17: 251-256
- Rundshagen U et al (2003) Mutations in the MATP gene in five German patients affected by oculocutaneous albinism type 4 Hum mutation 23: 106-110
- Terenziani M et al (2003) Amelanotic melanoma in a child with oculocutaneous albinism. Med Pediatr Oncol 41: 179-180
Incoming links (5)Basal cell carcinomatosis; Chromosome 9; Griscelli syndrome; Oca; Oculocutaneous albinism;
Outgoing links (8)Albinism, oculocutaneous, brown; Albinism oculocutaneous tyrosinase-negative; Albinism oculocutaneous tyrosinase-positive; Albinism, oculocutaneous, yellow mutant; Chediak higashi syndrome; Griscelli syndrome; Hermansky-pudlak syndrome; Waardenburg syndrome (overview);
Please ask your physician for a reliable diagnosis. This website is only meant as a reference.