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.
Oculocutaneous (pronounced Ock-you-low-kew-Tain-ee-us) 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 defined 10 different types of oculocutaneous albinism, and five types of ocular albinism, on the basis of their appearance by clinical examination. Newer laboratory research studying DNA has shown that there are numerous types of changes in the genes of those with albinism, including within families. Therefore, it is likely that the current system for naming types of albinism will change as research progresses.
The most common types of oculocutaneous albinism are called "ty-negative" and "ty-positive". Persons with ty-neg albinism have no melanin pigmentation, and more difficulty with vision. Those with ty-pos albinism have very slight pigmentation, and generally less severe visual difficulties. A table on page 2 summarizes the difference between these two main types of albinism.
Formerly, tests were done on the hair roots (or "hairbulbs") of individuals with albinism, to tell these types of albinism apart. However, these hairbulb tests cannot accurately identify types of albinism, particularly in young children, whose pigment systems are immature. Therefore haribulb 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. (An amino acid is a "building block" of protein, and comes from protein in the diet.) The genetic defect that causes albinism in other types of albinism is unknown, but it is speculated that it involves other enzymes used to make pigment.
Albinism is passed from parents to their children through genes. For nearly 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 parent has albinism), there is a one in four chance at each pregnancy that the baby will be born with albinism. This type of inheritance is called autosomal recessive inheritance.
If a parent has a child with albinism, it means the parent must carry the albinism gene. Until recently, unless a person has albinism or has a child with albinism, there was no way of knowing whether he or she carries the gene for albinism. Recently a test has been developed to identify carriers of the gene for ty-neg albinism and for other types in which the tyrosinase enzyme does not function. The test uses a sample of blood to identify the gene for the tryrosinase enzyme by its "code" in DNA. A similar test can identify ty-neg or similar albinism in utero, by aminiocentesis.
The above explanation of the inheritance of albinism does not apply to one type of ocular albinism, called X-linked ocular albinism. For X-linked inheritance, the gene for albinism is located on an X chromosome. Females have two X chromosomes, while males have one X chromosome and one Y chromosome. X-linked ocular albinism appears almost exclusively in males. The gene for it is passed from mothers who carry it to their sons. The mothers have subtle eye changes which an ophthalmologist could identify, but mothers generally have normal vision. For each son born to a mother who carries the gene, there is a one in two chance of having X-linked ocular albinism.
For specific information, seek the advice of a qualified genetic counselor. Genetic counselors are usually associated with universities and children's hospitals. NOAH can provide information about where genetic testing can be done. Those considering prenatal testing should be made aware that those with albinism can adapt well to their disabilities, and lead productive lives.
Eye conditions common in albinism include:
It is commonly thought that to have albinism, a person must have red eyes. In fact, most people with albinism have blue or grayish eyes. In some types of albinism, the irises appear to have a violet or reddish hue. The eyes appear this way because the iris has very little pigment, and allows light to reflect back from the reddish retina in the back of the eye.
For the most part, treatment of the eye conditions consists of visual rehabilitation. Surgery to correct strabismus may improve the appearance of the eyes. However, since surgery will not correct the misrouting of nerves from the eyes to the brain, surgery will not provide fine binocular vision. ( Binocular vision- using both eyes together- helps with depth perception at short distances. But binocular vision is only one of many ways the brain "sees" depth, and therefore it is not correct to say people with albinism have no depth perception.) In the case of esotropia or "crossed eyes," surgery may help vision by expanding the visual field, that is, the area that the eyes can see while looking a one point .
Tints and sunglasses can help with light sensitivity.
Various optical aids are helpful to people with albinism, and the choice of an optical aid depends on how a person uses his or her eyes in jobs, hobbies, or other usual activities. Some people do well with bifocals which have a strong reading lens. Others use hand-held magnifiers or special small telescopes. Others use contact lenses. Some use bioptics- glasses which have small telescopes mounted on, in, or behind their regular lenses, so that one can look either through the regular lens or through the telescope. Newer designs of bioptics use smaller light-weight lenses.
Optometrists or ophthalmologists who are experienced in working with people with low vision can recommend various optical aids. Clinics should provide aids on trial loan, and provide instruction in their use. The American Foundation for the Blind (see next page) maintains a directory of low vision clinics.
In the United States, people with albinism live normal life spans and have the same types of general medical problems as the rest of the population. (In tropical countries, those who do not use skin protection may develop life-threatening skin cancers.) If they use appropriate skin protection, such as sunscreen lotions rated 20 or higher, and opaque clothing, people with albinism can enjoy outdoor activities even in summer.
Persons with albinism area at risk of isolation, because the condition often is misunderstood. Social stigmatization can occur, especially among communities of color, where the race or paternity of a person with albinism may be questioned. Families and schools must make an effort not to exclude children with albinism from group activities.
Contact with others with albinism or having albinism in their families is most helpful. NOAH can provide the names of contacts in many regions of the country. The following page lists sources for more information.
NOAH (address and phone in logo above) publishes a large twice-yearly newsletter, NOAH News, as well as many Information Bulletins about albinism. The organization also sponsors national and regional conferences. Local chapters meet in many areas of the U.S. and Canada; NOAH can provide a list of chapters and contact persons. Founded in 1982 in Philadelphia, NOAH is an all-volunteer organization. NOAH's objectives are to provide information and support to individuals and families with albinism, to promote public and professional education about these conditions, and encourage research and research funding that will lead to improved diagnosis and treatment. Contact NOAH for more information, or to join.
American Foundation for the Blind hotline, phone 800-AFB-LIND, hours 8:30 a.m. to 4:30 p.m. Eastern time, provides information about programs and clinics for persons with impaired vision throughout the United States. Address: AFB, 15 West 16th Street, New York, NY 10011.
The Albino Fellowship is a Scotland-based international organization for people with albinism, their friends and families. The Fellowship publishes an informal newsletter. Write to Hon. Secretary, Henry McDermott, 16 Neward Crescent, Prestwick, Ayrshire, KA9TJB Scotland, phone 0292-70336.
NOAH can also provide information on organizations for people with albinism some other countries.