Albinism oculocutaneous (overview) E70.3

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 21.06.2022

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OCA; OCA3; OCA4; OCA5; OCA6; OCA7; Oculocutaneous albinism

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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.

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7 types are differentiated based on molecular differences:

  • OCA 1 (tyrosinase-negative OCA): Based on reduced or absent tyrosinase activity; approximately 80 mutations in the tyrosinase gene(TYR) have been described to date. OCA1A is the classic tyrosinase-negative oculocutaneous albinism; OCA 1B is also known as yellow albinism. OCA1Ts refers to temperature-sensitive oculocutaneous albinism (hair on cooler parts of the body darkens with age)
  • OCA 2 (tyrosinase-positive OCA): Caused by mutations in the P gene; the role of the P protein is still unclear; regulation of pH in melanosomes? OCA 2 is also called brown albinism or brown African albinism.
  • OCA 3 (OMIM 203290)- Red albinism: Caused by mutations in the "tyrosinase-related protein" gene(TYRP1 gene; the Tyrp1 protein is a melanocyte-specific gene product involved in eumelanin synthesis). OCA3 is associated with only mild ocular symptoms. Often remains clinically undetected. Frequently described in African American ethnic groups.
  • OCA 4 (OMIM 606574): Caused by mutations in a "membrane associated transporter protein" gene(SLC24A5 gene) that encodes a transport protein for melanin precursors. Variable clinical symptoms comparable to OCA type 2. 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 could be assigned to chromosomal locus 4q24, a gene locus likely coding for lysosomal proteins (Kausar T et al. 2013).
  • OCA 6: In OCA 6, as in OCA 4, a mutation of a transporter protein is present (chromosome 15q21.1).
  • In OCA7 (OMIM: 614537), a mutation was found in the"LRMDA gene" which is located on chromosome 10q 22.2-22.3. This gene encodes a protein that is significant for melanocyte differentiation. This rather mild variant was described in a consanguineous Faroese family (Gronskov K et al. (2013).

Further OCA genotypes are expected in the future.

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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)

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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).

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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).

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Oculocutaneous albinism can be associated with some rare syndromes:

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  1. 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
  2. Gronskov K et al (2013) Mutations in C10orf11, a melanocyte-differentiation gene, cause autosomal-recessive albinism. Am J Hum Genet 92: 415-421.
  3. Kamaraj B et al.(2014) Mutational analysis of oculocutaneous albinism: a compact review. Biomed Res Int doi: 10.1155/2014/905472.
  4. Kausar T et al. (2013) OCA5, a novel locus for non-syndromic oculocutaneous albinism, maps to chromosome 4q24. Clin Genet 84:91-93.
  5. King RA et al (2003) Tyrosinase gene mutations in oculocutaneous albinism 1 (OCA1): definition of the phenotype. Hum Genet 113: 502-513
  6. Kubasch A et al (2017) Oculocutaneous and ocular albinism. Dermatologist 68: 867-875
  7. King RA et al (2003) MC1R mutations modify the classic phenotype of oculocutaneous albinism type 2 (OCA2). Am J Hum Genet 73: 638-645.
  8. Nakamura E et al (2002) A novel mutation of the tyrosinase gene causing oculocutaneous albinism type 1 (OCA1). J Dermatol Sci 28: 102-105.
  9. Oetting WS et al (2003) Oculocutaneous albinism type 1: the last 100 years. Pigment Cell Res 16: 307-311.
  10. Okulicz JF et al (2003) Oculocutaneous albinism. J Eur Acad Dermatol Venereol 17: 251-256.
  11. Rundshagen U et al (2003) Mutations in the MATP gene in five German patients affected by oculocutaneous albinism type 4. Hum Mutat 23: 106-110.
  12. Terenziani M et al (2003) Amelanotic melanoma in a child with oculocutaneous albinism. Med Pediatr Oncol 41: 179-180


Please ask your physician for a reliable diagnosis. This website is only meant as a reference.


Last updated on: 21.06.2022