AlbinismThe word "albinism" refers to a group of hereditary conditions. People with albinism have little or no pigment in their eyes, skin, or hair. They have inherited genes that do not produce the usual amount of a pigment called melanin. One in 17,000 people suffer from some type of albinism. Albinism affects people of all races. Most children with albinism are born to parents who have normal hair and eye color for their ethnic origin. Albinism is found on the eleventh chromosome, section q, loci 14-21. Oculocutaneous albinism involves the eyes, hair, and skin. Ocular albinism primarily involves the eye. People with ocular albinism may also have slight lightening of hair and skin color, compared to other family members. Currently researchers have found 10 different types of oculocutaneous albinism and five types of ocular albinism. More recent laboratory research studying DNA has shown that there are numerous types of changes in the genes of people with albinism, even within families. The most common types of oculocutaneous albinism are called "ty-negative" and "ty-positive". People with ty-negative albinism have no melanin pigmentation and have greater visual difficulties. Those with ty-positive albinism have very mild pigmentation and generally less severe visual difficulties. Tests have been performed on the hair roots of individuals with albinism, to distinguish these types of albinism. However, these hair tests cannot identify types of albinism, particularly in young children, whose pigment systems are immature. Therefore hair tests are not useful in predicting the extent of a child's visual impairment. “Ty-Neg” (also called Type 1A) albinism results from a genetic defect in an enzyme called tyrosinase. Tyrosinase helps the body turn the amino acid tyrosine into pigment. The genetic defect that causes albinism in other types of albinism is unknown, but it is hypothesized to involve other enzymes used to produce the pigment. Albinism is passed from parents to children through genes. For almost all types of albinism, both parents must carry an albinism gene to have a child with albinism. Parents may have normal pigmentation but still carry the gene. When both parents carry the gene and neither has albinism, there is a one in four chance with each pregnancy that the child will be born with albinism. This type of inheritance is called autosomal recessive inheritance. If a parent has a child with albinism, it means that he or she must be a carrier of the albinism gene. Until recently, unless a person had albinism or had a child with albinism, there was no way to know whether that person carried the gene.