Oculocutaneous albinism , type

Nakamura, E. et al., A novel mutation of the tyrosinase gene causing oculocutaneous albinism type 1 (OCAl), J. Dermatol. Sci., 28,102,2002. 

Albinism is a disorder of the synthesis or processing of the skin pigment melanin (Fig. 47.2). Oculocutaneous albinism type 1 (OCA type 1) is an autosomal recessive disorder of tyrosinase resulting in the complete absence of pigment from the hair, eyes and skin. The lack of melanin in the skin makes patients with OCA type 1 vulnerable to skin cancer. 

Giebel, L. B., and Spritz, R.A. (1992). The molecular basis of type I (tyrosinase-deficient) human oculocutaneous albinism. Pigment Cell Res. Suppl. 2 101-106. 

King, R. A., Mentink, M. M., and Oetting, W. S. (1991). Non-random distribution of missense mutations within the human tyrosinase gene in type I (tyrosinase-related) oculocutaneous albinism. Mol. Biol. Med. 8 19-29. 

Albinism The most common type, oculocutaneous albinism, results in white hair, pink skin, and an extreme photophobia owing to lack of pigment in the eye Tyrosinase of the melanocyte is absent... 

The clinical symptoms of oculocutaneous albinism are of two types hypersensitivity of the skin to sunlight and photophobia. The skin is white and does not tan when exposed to ultraviolet radiation instead, the skin rapidly bums with erythema and desquamation. The incidence of skin cancer, normally high among blond individuals, is even higher among albinos. The iris has a blue-grey translucency. 

There are two forms of oculocutaneous albinism a tyrosinase negative due to a tyrosinase defect and a tyrosinase positive of unknown origin (probably caused by inavailability of tyrosine to the melanocyte). Both forms are inherited as autosomal recessive traits, but the genes for each type are found in different loci. Ocular albinism is inherited as an X-linked recessive trait. It is associated with vision defects, nystagmus, and head nodding. The metabolic defect is unknown. 

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