Saturday, December 13, 2008


(Hypopigmentation, Oculocutaneous Albinism, Ocular Albinism)
Albinism refers to a group of rare inherited disorders that are present from birth. Albinism affects the amount of pigment found in the skin, hair, and eyes. People with albinism usually have little to no pigment in their eyes, skin, and hair, but the degree of pigment loss can be quite variable. Many persons with this disorder have complete absence of pigment. Their skin, hair, and eyes lack all pigment from birth, and they do not develop freckles or moles at any time during their lifetimes. This form of albinism is known as “Type 1” and is divided into several subtypes depending on associated characteristics.
Other persons have decreased pigment, but may still have freckles and moles. This form of albinism, known as Type 2, is more common among persons of African descent and may be associated with such minimal pigment loss that it is evident only by comparison with other non-affected family members. Both Type 1 and Type 2 albinism are usually associated with visual problems including nystagmus (abnormal “jumping” movements of the eyes) and decreased visual acuity, which is frequently not fully improved with glasses or contact lenses. A third form, “ocular albinism” has loss of eye pigment and poor vision without any changes in skin or hair.
Albinism occurs as a result of altered genes, which are in most cases inherited from parents. Albinism appears in different forms and may be inherited by one of several modes: autosomal recessive, autosomal dominant, or X-linked.
Autosomal recessive inheritance accounts for the vast majority of cases. This means that while both parents carry one copy of an abnormal gene, they have no symptoms or signs of albinism. Children become affected only if they inherit one affected gene from each parent. In this form of inheritance, each child has a one-in-four chance of inheriting the condition. The abnormal gene reduces (or completely eliminates) the body’s ability to make a pigment called melanin. There are several dozen different genetic subtypes of albinism which affect melanin production. Individuals can have full or partial absence of this pigment which will affect the color of eyes, hair, and skin.
Albinism is rare. In the United States, about 1 in 17,000 inidividuals overall has some form of albinism. All races are affected, though Type 1 occurs predominantly in whites and Type 2 in blacks. Most children with albinism are born to parents with normal hair and skin color for their ethnic background. While albinism is always apparent at birth, it may be so mild that affected persons are unaware of their diagnosis unless abnormal eye movements or vision develop.
Risk Factors
A risk factor is something that increases your chances of getting a disease or condition. Albinism is a hereditary disorder. Therefore, people at risk of inheriting albinism are:
• Children of parents who have albinism
• Children of parents who do not have albinism, but carry the altered genes that cause this disorder
• A positive family history for albinism in a sibling or other relative
• Puerto Rican anscestry (this significantly increases the risk of an otherwise rare form of albinism known as Hermansky-Pudlak syndrome)
The symptoms of albinism depend on the specific type of albinism one has. Some types affect the skin, hair, and eyes. Other types affect only the eyes or only the skin.
Symptoms may include:
• Eye problems, such as:
o Poor vision (which usually cannot be fully corrected with glasses or contacts)
o In some cases, functional blindness
o Nystagmus–irregular, rapid eye movement.
o Amblyopia, or “lazy” eye.
o Photophobia–sensitivity to bright lights or glare
o Strabismus, or crossed or wandering eye
• Skin problems, including:
o Little or no pigmentation (resulting in extremely light or white skin)
o Patches of low pigmentation (resulting in patches of extremely light or white skin)
o Extreme sensitivity to sunburn
o Very high susceptibility to skin cancer
• Hair problems, including:
o White hair
o Portions of the hair (often the forelock) being white
• Certain rare types of albinism, such as Hermansky-Pudlak syndrome, can cause other symptoms, including:
o Bleeding disorders
o Lung disease
o Bowel disease
o Infections
o Hearing loss
o Nervous system disorders
o The common forms, Type 1 and 2 albinism are not associated with these more serious symptoms.
In many types of albinism, the disorder can be diagnosed by observation of major or total absence of pigmentation of the hair, skin, and eyes. If needed, chemical testing of hair can provide an easy confirmation of the diagnosis. Because most types of albinism affect the eyes, certain eye tests (including an electroretinogram) are used to help confirm the diagnosis. For some types of albinism, DNA genetic testing can also be used to confirm the diagnosis.
There is no cure for albinism. Treatment is aimed at preventing or limiting symptoms. In some cases, specific treatment for certain symptoms is needed. The skin and eyes must be protected from the sun. Sunglasses (UV protected) may relieve photophobia. Sunburn and skin cancer risks can be reduced by avoiding the sun, the use of sunscreens, and complete coverage with clothing when exposed to sun. Sunscreens should have a high SPF (sun protection factor)—15 or higher.
Preventive Treatment
Preventive treatment may include:
• To protect the skin:
o Avoid exposure to the sun as much as possible.
o Wear sunscreen with high SPF (sun protection factor).
o Cover as much skin as possible with clothing when exposed to the sun.
• To protect the eyes:
o Wear sunglasses with UV protection whenever exposed to the sun.
Specific Treatment of Symptoms
Specific treatment of symptoms for albinism may include:
• For eyes:
o Glasses, contacts, and/or optical aids to help improve vision.
o Surgery to correct certain eye problems, including crossed eyes or “lazy” eye.
o Visual aids (in the classroom) to help children with albinism
• For skin:
o Surgery to treat and/or remove skin cancer, if necessary.
These treatments may be of special importance in Africa where the World Health Organization estimates that thousands of affected individuals live—many without access to important medical and preventive care.
Studies in mice with genetic forms of albinism suggest that gene transfer may prevent visual disturbances. Whether these results may someday be applied to people with ocular albinism remains to be seen.
• Patients with the most common forms of Type 1 and Type 2 albinism and ocular albinism have a normal lifespan.
• An increased risk of skin cancer exists; however, with careful ongoing surveillance this risk can be minimized. Since melanoma skin cancer may occur without characteristic pigmentation, a high level of dermatologic vigilance is required to ensure early diagnosis.
• Affected patients usually have unaffected children unless married to another individual with albinism.
• Albinism does not cause a delay in development or mental retardation.
There is no known way to prevent albinism. If you have albinism or have a family history of the disorder, you can talk to a genetic counselor when deciding to have children to understand the risks to your offspring.