Oculocutaneous albinism is a group of conditions that affect coloring (pigmentation) of the skin, hair, and eyes. Approximately 1 in 20,000 exhibit this disorder and affected individuals typically have very fair skin and white or light-colored hair. Long-term sun exposure greatly increases the risk of skin damage and skin cancers, including an aggressive form of skin cancer called melanoma. Albinism also reduces pigmentation of the colored part of the eye known as the iris and the light-sensitive tissue at the back of the eye called the retina. People with this condition usually have vision problems such as reduced sharpness, rapid, involuntary eye movements (nystagmus), and increased sensitivity to light (photophobia). Melanin is an extremely important molecule in humans for many reasons, one being its ability to protect the DNA in the cell’s nucleus from damage by UV light from the sun. This is one reason the skin darkens after being exposed to sunlight and people living closer to the equator have darker skin for this extended protection.
Albinism is not only seen in humans, as it is actually found across all major animal groups since nearly all produce melanin. It has been observed in countless species of mammals, birds, reptiles, amphibians, fish and even invertebrates. This is not surprising since the gene for melanin production, the protein responsible for producing pigment in skin, hair and eyes, is similar among these species. All it takes is one small change to result in a change in this protein’s shape to make it non-functional.
Albinism: From genotype to phenotype (pdf file)
Introductory Pedigree & Gene Map (pdf file)
Albinism Advanced: Across the Species (pdf file)
Albinism Lab Sequence Key (pdf file)
HHMI’s Biointerative – Human Skin Color: Evidence for Selection (HHMI Link)