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Oculocutaneous albinism type 3
Type 3 oculocutaneous albinism (OCA3) is a form of oculocutaneous albinism (OCA; see this term) characterized by rufous or brown albinism and occurring mainly in the African population.
ORPHA:79433Classification level: Disorder
OCA3 has an estimated prevalence of 1/8,500 individuals in Africa. It is rarely seen in other populations.
Visual anomalies, such as nystagmus, are frequently undetectable and patients usually present with one of two phenotypes: rufous OCA (ROCA), characterized by red-bronze skin color, blue or brown irises and ginger-red hair, or brown OCA (BOCA), characterized by light to brown hair and a light to brown or tan skin color. The clinical features of OCA3 have been considered as rather mild, and in the rare cases of non-African patients, reddish hair color has been reported. A Japanese girl was reported with having OCA3 who presented with blond hair and light skin (with a small Mongolian spot), was able to tan and was negative for nystagmus.
OCA3 is caused by a mutation in the tyrosinase-related protein 1, TYRP1, gene located on chromosome 9p23. The majority of BOCA cases are seen in OCA2, but a few BOCA phenotypes have been reported with mutations in the TYRP1 gene, indicating OCA3.
OCA3 is inherited autosomal recessively and genetic counseling is possible.