Albinism

Inheritance	autosomal recessive
Occurrence	1 in 17,000 in the United States
Description	disorder characterized by absence of pigment in hair, skin, and eyes
Testing	testing cannot be accurately done unless a couple already has a child with albinism-- in these circumstances albinism can be detected through amniocentesis
Cause	a genetic defect in an enzyme called tyrosinase (the gene is found on chromosome 11)

Melanin

Melanin is a pigment found in our skin that absorbs UV light and prevents damage to our skin. Most students will be familiar with melanin as the pigment in human skin responsible for tanning. When we are exposed to the sun, our bodies increase the amount of melanin in our skin; this is known as a tan. We make melanin by converting the amino acid tyrosine into melanin by the enzyme tyrosinase. Individuals with albinism have no melanin in their skin because they cannot convert tyrosine to melanin. They have fair skin and hair and do not tan. The other place in our body where we use melanin is in our eyes. In the absence of melanin the fovea (found on the retina) does not develop properly. It is partly due to this that most individuals with albinism have reduced visual acuity.

Give the class an assignment (in groups or individually) to research skin cancer. Once they have discovered many of the basics (which should include a simple understanding of how we tan and the role melanin plays), initiate a discussion on the role of melanin in our bodies. Ask if anyone knows how melanin is formed. Allow students time to think and hypothesize. After some time (if no one knows) explain how tyrosine (an amino acid) is converted to melanin.

Next, you might assign students to determine what would happen if the enzyme tyrosinase did not function properly and no melanin was formed. Then discuss what they think will happen. Here are some possible conclusions.

(2) Since melanin protects skin from sun (UV) damage, skin without melanin would be more susceptible to skin cancer.

(3) Hopefully some students will realize that individuals with no melanin would lack all pigment and have albinism.

It may then be appropriate to discuss the increased risk of skin cancer and sunburn in individuals with albinism. This can lead into a discussion on skin cancer and what ethnic/racial groups are at higher/lower risk for developing skin cancer. Many students should have found risk factors such as fair skin, light colored hair, blue eyes, Scandinavian heritage and many others. Have students share information on the different kinds of skin cancer and the risk of both sunburns and tanning.

Albinism (Oculocutaneous)

Melanin