Albinism :: essays research papers

Albinism     The word "albinism" refers to a group of inherited conditions. Peoplewith albinism pose little or no rouge in their oculuss, skin, or cop. They fork upinherited genes that do not make the usual amounts of a pigment c alled melanin.One person in 17,000 has some type of albinism. Albinism affects people from allraces. Most children with albinism are born to parents who have normal hair andeye color for their ethnic backgrounds. Albinism is found on the eleventhchromosome, section q, loci 14-21.Oculocutaneous albinism involves the eyes, hair, and skin. opthalmic albinisminvolves primarily the eye. People with ocular albinism may have slight cheer of hair and skin colors as well, compared to other family members. At feed researchers have found 10 different types of oculocutaneous albinism,and five types of ocular albinism. Newer science laboratory research studying DNA hasshown that thither are numerous types of changes in the genes of tho se withalbinism, including within families.The most common types of oculocutaneous albinism are called "ty-negative"and "ty-positive". Persons with ty-negative albinism have no melaninpigmentation, and to a greater extent difficulty with vision. Those with ty-positive albinismhave very slight pigmentation, and generally less distasteful ocular difficulties.Tests were d one and only(a) on the hair roots of individuals with albinism, to tell thesetypes of albinism apart. However, these hair tests cannot identify types ofalbinism, particularly in young children, whose pigment systems are immature. whence hair tests are not helpful in predicting the extent of visualdisability of a child.     "Ty-Neg" (also called Type 1A) albinism results from a genetic defect inan enzyme called tyrosinase. Tyrosinase helps the body to change the amino acidtyrosine into pigment. The genetic defect that causes albinism in other types ofalbinism is unknown, bu t it is speculated that it involves other enzymes used tomake pigment.     Albinism is passed from parents to their children through genes. For closely all types of albinism both parents must fly the coop an albinism gene to have achild with albinism. Parents may have normal pigmentation but still carry thegene. When both parents carry the gene, and neither parent has albinism, thereis a one in four chance at each pregnancy that the frustrate will be born withalbinism. This type of inheritance is called autosomal recessionary inheritance.     If a parent has a child with albinism, it means the parent must carrythe albinism gene. Until recently, unless a person has albinism or has a childwith albinism, there was no way of knowing whether he or she carries the gene