About the genetic disorder, Albinism. Very well written Excellent job!
The word 'albinism' refers to a group of inherited conditions. People with albinism
have little or no pigment in their eyes, skin, or hair. They have inherited genes that do not
make the usual amounts of a pigment called melanin. One person in 17,000 has some type
of albinism. Albinism affects people from all races. Most children with albinism are born to
parents who have normal hair and eye color for their ethnic backgrounds. Albinism is
found on the eleventh chromosome, section q, loci 14-21.
Oculocutaneous albinism involves the eyes, hair, and skin. Ocular albinism involves
primarily the eye. People with ocular albinism may have slight lightening of hair and skin
colors as well, compared to other family members. At present researchers have found 10
different types of oculocutaneous albinism, and five types of ocular albinism. Newer
laboratory research studying DNA has shown that there are numerous types of changes in
the genes of those with albinism, including within families.
The most common types of oculocutaneous albinism are called 'ty-negative' and
'ty-positive'. Persons with ty-negative albinism have no melanin pigmentation, and more
difficulty with vision. Those with ty-positive albinism have very slight pigmentation, and
generally less severe visual difficulties. Tests were done on the hair roots of individuals
with albinism, to tell these types of albinism apart. However, these hair tests cannot
identify types of albinism, particularly in young children, whose pigment
systems are immature. Therefore hair tests are not helpful in predicting the extent of visual
disability of a child.
'Ty-Neg' (also called Type 1A) albinism results from a genetic defect in an
enzyme called tyrosinase. Tyrosinase helps the body to change the amino acid tyrosine into
pigment. The genetic defect that causes albinism in other types...