Albinism

Albinism is an inherited condition in which a person lacks the usual amount of the pigment melanin, which is the substance that gives color to skin, hair, and eyes.

Albinism (AL-bi-niz-im) is a group of disorders that occur when a person inherits various genes * that are defective in their ability to make the pigment melanin (MEL-a-nin). Melanin is the main substance that determines a person's skin, hair, and eye color. In the United States, albinism affects approximately one in 17,000 people, although certain types of albinism are more prevalent among specific groups of people. In some parts of Africa, for instance, about one in 1,000 people experience the condition. The outward signs of albinism vary according to the amount of pigment a person has, and many people with albinism have skin much lighter than that of their family members. Caucasians with albinism may have white to light-blond hair, pinkish-white skin, and blue eyes, while people who are black may have yellowish hair, skin with a cream-colored tint, and hazel or green eyes. In some people with albinism, the eyes look pink because they contain no pigment to mask the red of the blood vessels in the retina * .

Albinism always affects vision to some degree. The genes responsible for albinism cause abnormal development of the nerve connections between the eyes and the brain. The retina and the iris (the colored portion of the eye) are also affected by albinism.

What Causes Albinism?

• OCA type 1: This form of albinism, which is characterized by almost no pigmentation, is caused by a defect in a gene for an enzyme *
  Albinism and the Eyes

  Vision is always affected by albinism. Vision problems that can affect people with albinism include:

  • Sensitivity to bright light
  • Misaligned eyes—crossed or lazy eyes
  • Back-and-forth movement of the eyes
  • Farsightedness
  • Nearsightedness
  • Blurry vision

  Most people with albinism are born to parents without the condition, but both parents must carry a copy of the defective gene, and both must pass on that copy to their child. Albinism is a recessive trait, meaning that if a person inherits even one good copy of the gene, that person will not have the condition. Parents who both carry the trait have a 25 percent chance that each of their newborn children—either boy or girl—will have albinism. Ocular albinism is the exception because most of these cases are caused by a sex-linked genetic defect, which means that the defective gene is carried by the X chromosome * , which is one of two chromosomes that determine a person's sex. Sex-linked diseases occur most often in males.

  Living with Albinism

  Vision and skin care are major considerations for people with albinism. The lack of pigment makes eyes and skin very sensitive to sunlight, and the skin prone to sunburn. The latter, a feature of people with oculocutaneous albinism, can lead to premature aging of the skin and skin cancer. The use of sunscreen, hats, and protective clothing can help prevent overexposure to the sun. Similarly, people with oculocutaneous and with ocular albinism should use sunglasses to shade their eyes, and should take care to avoid direct and bright indoor lights, as well as glare from shiny surfaces both indoors and outdoors. Some people with albinism find that their vision problems can be corrected with glasses, but others may require surgery. While many people with albinism can see well enough to drive a car, many others are legally blind. All people with albinism need consistent and continuing eye care.

  While people with most forms of albinism have a normal life expectancy, they may face social and emotional hurdles as they learn to live with being different. Support from family and friends is especially important to helping a child with albinism build self-esteem.

  See also Blindness • Eye Disorders: Overview • Genetic Diseases: Overview

* genes (JEENS) are chemical structures composed of deoxyribonucleic acid (DNA) that help determine a person's body structure and physical characteristics. Inherited from a person's parents, genes are contained in the chromosomes found in the body's cells.

* retina (REH-tuh-na) is the tissue that forms the inner surface of the back of the eyeballs; it receives the light that enters the eye and transmits it through the optic nerves to the brain to produce visual images.

* enzyme (EN-zime) is a protein that helps speed up a chemical reaction in cells or organisms.

* chromosome (KRO-mo-zom) is a unit or strand of DNA, the chemical substance that contains the genetic code to build and maintain a living being. Humans have 23 pairs of chromosomes, for a total of 46.