[Oculo-cutaneous albinism in man. Biochemical, genetic, clinical, and population aspects]

Abstract

Oculocutaneous albinism comprises hereditary disorders in which there is a congenital absence or reduction of melanin in the skin, hair and eyes, coupled with nystagmus, photophobia and reduced visual acuity. The body is unable to make melanin (a compound derived from the metabolism of tyrosine) due to the functional absence of the enzyme tyrosinase. The disease is transmitted as an autosomal recessive character. In man, there are six conditions distinguishable in relation to their frequency, and their clinical, biochemical, ultrastructural, and genetic characteristics. The attempt to identify the heterozygote has led to contradictory results. Abnormal transparency of the iris has only been observed in some heterozygotes, and this feature cannot be used to recognise carriers. As far as treatment is concerned, the two main problems are sensitivity to sunlight, with concomitant susceptibility to skin tumors, and collateral vision disturbances. Subjects should avoid direct sunlight. Photophobia can be reduced by wearing sunglasses.