Albinism :: essays research papers

Albinism     The word "albinism" refers to a group of inherited conditions. Peoplewith albinism absorb little or no hue in their essences, skin, or copper. They peeinherited genes that do not make the usual amounts of a pigment c eached 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. visual albinisminvolves primarily the eye. People with ocular albinism may have slight lighten up of hair and skin colors as well, compared to other family members. At correspond researchers have found 10 different types of oculocutaneous albinism,and five types of ocular albinism. Newer laboratory research studying DNA hasshown that thither are numerous types of changes in the genes of t hose 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 stark(a) visual difficulties.Tests were d matchless 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.thusly 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, but it is s peculated that it involves other enzymes used tomake pigment.     Albinism is passed from parents to their children through genes. For close to all types of albinism both parents mustiness load down 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 botch up 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