Albinism

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Albinism

Definition

Albinism is an inherited condition that causes a lack of pigment in the hair, skin or eyes.

Description

People with albinism typically have white or pale yellow hair, pale skin and light blue or gray eyes. Since their irises have little pigment, their eyes may appear pink or violet in different types of light. This is because light is being reflected from the reddish part of the retina

in the back of the eye. Their skin usually does not tan and their eyes are often sensitive to light. Many have trouble with vision. Some children may be born with albinism, but develop some pigmentation as they grow older.

In albinism, the body does not produce enough of a pigment called melanin, which creates hair, skin and eye color. Melanin protects the body by absorbing the sun's ultraviolet light. There are several types of albinism: some affect only the eyes, while others affect the skin and hair or other parts of the body.

Types of albinism

Ocular: A form of albinism that mainly affects the eyes. People with ocular albinism have some pigmentation, but may have lighter skin, hair and eye color than other family members. Scientists have identified five different types of ocular albinism.

X-linked ocular: This type of albinism occurs mostly in males, who inherit the gene from their mothers. It causes visual disabilities.

Oculocutaneous: A type of albinism that affects the hair, skin and eyes. Researchers have classified 10 different types of oculocutaneous albinism.

Tyrosinase-negative oculocutaneous: Also known as Type 1A, this is the most severe form of albinism, marked by a total absence of pigment in hair, skin and eyes. People with this type of albinism have vision problems and sensitivity to sunlight. They also are extremely susceptible to sunburn.

Tyrosinase-positive oculocutaneous: People with this type of albinism have light hair, skin and eye coloration and fewer visual impairments.

Hermansky-Pudlak syndrome (HPS): This rare type of albinism is common in the Puerto Rican community. Approximately one person in every 1,800 people in Puerto Rico will be affected by it. The lack of pigmentation can vary widely. People with HPS may have white, pale yellow or brown hair, but it always is lighter than the rest of the population. Their eyes range from blue to brown, and their skin can be creamy white, yellow or brown. HPS also often causes visual changes, along with other physical symptoms.

Chediak-Higashi syndrome : A rare type of albinism that interferes with white blood cells and the body's ability to fight infection.

Black Locks Albinism Deafness syndrome (BADS): Another rare form of albinism identified by a black lock of hair on the forehead. BADS causes deafness from birth.

Piebaldism: Also known as partial albinism, this condition is marked by patches of white hair or lighter skin blotches on the body.

Genetic profile

Children inherit the genes for albinism from their parents. The parents may have normal pigmentation, but if both the mother and father carry a recessive gene, there is a one in four chance their child will have albinism.

A specific genetic abnormality causes tyrosinasenegative oculocutaneous albinism (Type 1A). In this type, also called "ty-neg albinism," the body is unable to convert the amino acid tyrosine into pigment. The genes for producing the enzymes related to ty-neg albinism are located on chromosome 11 and chromosome 9.

Similarly, scientists believe the gene that causes Hermansky-Pudlak syndrome is on chromosome 10. They are studying two other genes that appear to be involved in melanin pigment formation: the P gene on chromosome 15 and the ocular albinism gene on the X chromosome.

Women who carry the gene for X-linked ocular albinism may have normal vision, but they have a one in two chance of passing it on to their sons. This type of albinism occurs mainly in males because the gene that causes it is located on the X chromosome. Since males only have one X chromosome, genetic abnormalities on this chromosome will almost always be expressed.

Demographics

Albinism affects one in every 17,000 people. All racial groups, including African-Americans and Latinos are affected by albinism. Asians have the lowest incidence of this condition.

Signs and symptoms

Eye problems

The lack of pigment in albinism causes abnormal development in the eye. For example, the iris (the colored ring around the center of the eye), which normally acts as a filter, may let too much light into the eye. Communication between the retina (the surface inside the eye that absorbs light) and the brain may also be altered in people with albinism, causing a lack of depth perception. These changes can lead to visual impairments, such as sensitivity to sunlight, near-sightedness, far-sightedness, or astigmatism (a curvature in the lens that makes it difficult to focus on objects). Other common affects of albinism on the eyes include nystagmus, a constant, involuntary shifting of the eyes from side to side; and strabismus, a disorder of the muscles in the eyes that causes a wandering eye or crossed eyes. Strabismus can interfere with depth perception.

Skin conditions

People with albinism burn easily in the sun. Since they have no pigmentation, or very little, they typically do not tan. Without adequate protection, they are more likely to develop skin cancer . Some people with albinism will have freckles, or large blotches of pigmentation, but they still will not develop a suntan.

Other rare symptoms

People with HPS may experience a variety of health problems related to their unique form of albinism. For example, HPS can cause scarring of the lungs, or fibrosis, which leads to restrictive lung disease and causes fatigue and problems with breathing. Some people with HPS have trouble healing when they cut their skin because the disorder interferes with normal platelet function. Platelets are a component of blood needed for clotting. This complication may cause people with HPS to bruise easily, have frequent nosebleeds or trouble with bleeding gums when brushing their teeth. It also could cause heavy menstrual bleeding and excessive bleeding when a pregnant woman with HPS delivers a child. Intestinal difficulties also are associated with HPS. It can cause a condition called granulomatous colitis, which causes abdominal cramps, intestinal bleeding and diarrhea. People with HPS may also have kidney disease.

Other rare forms of albinism may cause deafness or decrease the body's ability to fight infection.

Diagnosis

Physicians are able to diagnose albinism by carefully examining a person's hair, skin, eyes, and family history. Diagnostic testing usually is not necessary, but a genetic test is now available for parents who want to find out if they are carriers of ty-neg albinism. The test also can be performed on an infant by amniocentesis at 16 to 18 weeks gestation.

In the past, doctors used to examine a sample of the root of a person's hair, in a procedure known as a hairbulb pigmentation test. They also tested hair for the presence of tyrosine, a substance in the body that produces melanin, to determine the type of albinism a person had. Today, however, most physicians believe these tests are not reliable and they are not often used.

To find out if a person has HPS, physicians can take a sample of their blood and examine the platelets under a microscope to look for a lack of clotting ability.

Eye doctors may be able to identify subtle eye changes in women who carry the gene for X-linked ocular albinism. While their eye color may appear normal, female carriers of this type of albinism often have a slight lack of pigment in their retinas.

Treatment and management

People with albinism must shield their sensitive eyes from the sun with UV protected sunglasses. Some find bifocals and other corrective lenses to be helpful. For those with severe forms of albinism, however, corrective lenses may not be able to overcome problems caused by developmental changes in the retina. Children with albinism may require special accommodations, such as large-print textbooks, for reading in school. If visual impairment is severe, it may affect the individual's ability to drive.

For those with strabismus, surgery can alter their appearance, although the procedure may not significantly improve their vision. Before trying surgery, some doctors have children wear an eye patch in an attempt to strengthen the weaker eye. Eye surgery may also help reduce the involuntary eye movements associated with nystagmus, but vision will not always improve.

To prevent sun-related health problems, people with albinism must cover up with a sunscreen of SPF 20 or higher. Protective clothing, hats or visors are essential. Physicians also recommend keeping a careful watch for any changes in birth marks or moles that could become cancerous.

People with HPS should be careful to avoid aspirin, which can reduce clotting, and notify their dentist before having any dental work done. Women with HPS should alert their gynecologist or obstetrician. Some physicians recommend wearing a medical alert bracelet for the bleeding disorder. To avoid exacerbating the lung disease, people with HPS should not smoke.

Children with albinism may need extra support from family or a counselor if they are exposed to teasing or hurtful comments at school. Many families also find support groups to be helpful.

Prognosis

People with albinism can easily adapt to this condition and live healthy, productive lives. Albinism does not affect a person's lifespan, although it may lead to an increased risk of skin cancer if protective measures are not taken.

Resources

BOOKS

Larry. National Association for the Visually Handicapped, New York.

Wiley, Jean. To Ride the White Rainbow. National Organization for Albinism and Hypopigmentation (NOAH), 1998.

PERIODICALS

"NOAH News." Newsletter of the National Organization for Albinism and Hypopigmentation, Philadelphia.

Wilson, Tracy. "The paler side of beauty." Heart and Soul. Vol. 6, Issue 1 (February, 1999): 30-33.

ORGANIZATIONS

American Academy of Dermatology. PO Box 4014, 930 N. Meacham Rd., Schaumburg, IL 60168-4014. (847) 330-0230. Fax: (847) 330-0050. <http://www.aad.org>.

American Council of the Blind. 1155 15th St. NW, Suite 1004, Washington, DC 20005. (202) 467-5081 or (800) 424-8666. <http://www.acb.org>.

American Nystagmus Network. PO Box 45, Jenison, MI 49429-0045. <http://www.nystagmus.org>.

Hermansky-Pudlak Syndrome Network. 39 Riveria Court, Malverne, NY 11565-1602. (800) 789-9477 or (516) 599-2077. <http://www.medhelp.org/web/hpsn.htm>.

International Albinism Center. University of Minnesota, PO Box 420, Delaware St. SE, Minneapolis, MN 55455. <http://www.cbc.umn.edu/iac>.

National Association for Parents of Children with Visual Impairment (NAPVI). PO Box 317, Watertown, MA 02472. (617) 972-7441 or (800) 562-6265. <http://www.spedex.com/napvi>.

National Organization for Albinism and Hypopigmentation. 1530 Locust St. #29, Philadelphia, PA 19102-4415. (215) 545-2322 or (800) 473-2310. <http://www.albinism.org>.