Albinism oculocutaneous

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 refers to a group of conditions in which a defect in tyrosine metabolism results in a deficiency in the production of melanin. These defects result in the partial or full absence of pigment from the skin, hair, and eyes. Albinism appears in different forms, and it may be inherited by one of several modes autosomal recessive, autosomal dominant, or X-linked. Complete albinism (also called tyrosinase-negative oculocutaneous albinism) results from a defi ciency of tyrosinase activity, causing a total absence of pigment from the hair, eyes, and skin (Figure 20.20). It is the most severe form of the condition. Affected people may appear to have white hair, skin, and iris color, and they may have vision defects. They also have photophobia (sunlight is painful to their eyes), they sun burn easily, and do not tan. 

Patient with oculocutaneous albinism, showing blond hair and white eyebrows and lashes. 

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... 

Lung and kidney disease, oculocutaneous albinism, CNS involvement... 

This boy has no history of any major medical illness that might have influenced his neurological development. He has a hypomelanotic skin condition (oculocutaneous albinism), but no vision or hearing impairments and no motor abnormalities. His developmental deficits are apparently restricted to communication, cognition, and social interactions. 

Bakare M. O. Ikegwuonu, N. N. (2008). Childhood autism in a 13 year old boy with oculocutaneous albinism a case report. J. Med. Case Reports. 2 56. 

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. 

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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