Albinism

This is lack of melanin pigmentation in the skin. Individuals affected (albino) lack melanin forming gene. Albino do not have normal skin pigmentation. They have a light coloured skin, white hair and pink eyes.

Melanin is a derivative of the amino acids phenylalanine and tyrosine, and is synthesized through a series of controlled by a specific gene.

In albinism, one of this gene (designated by letter A) is substituted by a recessive gene (designated by a). Gene a in a homozygous condition aa blocks in one or two places of the chain reactions involved in the synthesis of melanin. This is a result of one of the enzymes (tyrosinase) failing to be formed in the presence of the recessive gene. Consequently melanin is not formed and albinism results. The genotype of an albino is homozygous recessive aa. A carrier for albinism is heterozygous with the genotype Aa and has normal skin pigmentation. In a family an albino child can be born if both parents are carriers of the recessive gene.

Therefore the probability that any child born to carrier parents will be an albino is 1/4. The probability that any of their children is a carrier is  1/2.

The skin of an albino person is susceptible to sunburn and the eyes are sensitive to bright light. Use of sunglasses and sunscreen lotions enable them to lead a normal life.