Type 2 oculocutaneous albinism (tyrosinase positive)

Oculocutaneous albinism type 2 is an autosomal recessive disease characterized by a variable reduction of pigmentation in the skin, hair and eyes. It is caused by variants in the OCA2 gene that produces a melanin precursor.

Oculocutaneous albinism type 2 (OCA2) is the most common form of OCA in the world population and is characterized by variable hypopigmentation of the skin and hair and numerous characteristic ocular changes.

OCA2 is caused by a mutation in the OCA2 gene, which encodes the OCA2 protein involved in melanin production. Melanocytes produce small amounts of melanin, but it is mainly yellow pheomelanin.

The worldwide prevalence of OCA2 is estimated to be 1 in 38,000, with the exception of the African population, which has a prevalence of 1:3,900.

Symptoms

Newborns with OCA2 almost always have some yellow or tan in the hair, eyebrows and eyelashes unlike newborns with oculocutaneous albinism type 1 (OCA1) who have no or minimal melanin. African and African-American individuals with OCA2 usually have yellow hair and blue-gray or hazel irises.

OCA2 causes visual disturbances that are usually milder than in patients with OCA1 such as: reduced pigmentation of the retina and iris, reduced visual acuity and rapid involuntary eye movements (nystagmus).

Another difference with OCA1 is that in people with OCA2 freckling (lentigines and ephelides) is common.

Disease management

Use of glasses or contact lenses for the correction of farsightedness or nearsightedness and astigmatism, which are usually present in most albino people. As bright light is often bothersome, it is advisable to wear dark glasses and a hat with brims.

It is important to take care of the skin with creams and clothes with sun protection following the recommendations of a dermatologist.

Genes analyzed

OCA2

Bibliography

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