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Albinism
Tuesday, 24 August 2004
Tuesday, 24 August 2004
Oculocutaneous Albinism, Ocular Albinism

What

Albinism is a group of disorders in which melanocytes, or pigment cells, are dysfunctional, causing a lack of pigmentation of the skin, eyes, and hair. Individuals are born with white hair and skin and the iris of the eye is translucent. In many cases, the skin, hair, and eyes will darken with age or with sun exposure. Additionally, individuals may have reduced vision. There are generally two types of albinism: ocular, which affects only the eyes, and oculocutaneous, which affects the eyes, skin, and hair.

Who

There are several types of albinism, including Oculocutaneous Albinism (OCA) Types 1, 2, and 3, Ocular Albinism (OA), and several others that have been described but not categorized. In addition, some other genetic disorders, such as Chedíak-Higashi syndrome are also associated with decreased pigmentation, though that is not the main problem in the disorder. Except for Ocular Albinism, all types of albinism affect males and females equally. Ocular Albinism is found predominantly in the male population. The frequency and racial/ethnic profiles of the different types of Albinism are listed below. • OCA Type 1: 1 out of 40,000 • OCA Type 2: 1 out of 38,000-40,000 in the general population 1 out of 1,500-8,000 in the African population 1 out of 10,000 in the African American population • OCA Type 3: unknown, but found primarily in African and African American populations • OA: 1 male out of 60,000 live births

Signs and Symptoms

The following signs and symptoms may be found in children with Oculocutaneous Albinism or Ocular Albinism. Oculocutaneous Albinism

  • White skin that may darken with age or tan with sun exposure
  • White or light yellow hair that may darken with age or sun exposure. Children with OCA Type 2 typically have pigmented hair, ranging from light yellow to brown.
  • Translucent or reduced pigmentation of the iris of the eye that may turn to green/hazel or brown with age
  • Reduced vision usually in the range of 20/100 to 20/400 • Nystagmus (involuntary back and forth movements of the eye) • Strabismus (in which the eyes are not perfectly aligned) Ocular Albinism
  • Reduced vision.
  • Reduced pigmentation and translucency of the irises
  • Nystagmus In addition, because of the reduced pigmentation, people with albinism are at greater risk for certain skin cancers, and their skin may become sun damaged more easily.

Possible Causes

All types of Albinism are caused by genetic defects that affect the production of melanin, which provides pigmentation of the eyes, hair, and skin. OCA Types 1, 2, and 3 are inherited in an autosomal recessive manner, meaning that two copies of an altered gene must be present to cause Albinism. One copy of the mutated gene is received from each parent. Ocular Albinism is an X-linked recessive disorder, in which the altered gene involved in OA is found on the X chromosome. Because males have only one copy of the X chromosome (females have two), they are more likely to have Ocular Albinism. Male children inherited the altered X chromosome from their mothers. Although very rare, females can have OA if both parents have X chromosomes with the altered gene.

Diagnosis

The diagnosis of Albinism is based on clinical findings of physical symptoms. The types of OCA are categorized based on the severity of reduced pigmentation. OCA Type 1 has a near complete loss of pigmentation, whereas OCA Type 2 has minimal to moderate loss of pigmentation. OCA Type 3, which is found in African and African American populations, has minimal reduction of pigmentation and may only be diagnosed based on comparison to the pigmentation of family members. There are a variety of genes that cause OCA, depending on the type, and many of these can be distinguished by genetic testing. Ocular Albinism is diagnosed based on reduced pigmentation and translucency of the irises and other ocular abnormalities.

Treatment

There is currently no treatment for Albinism. If the child has reduced visual acuity, glasses or other corrective lenses are prescribed to improve vision. Because children with Albinism cannot produce enough melanin to protect their skin from sun exposure, protective clothing (brimmed hats, long sleeves, and pants) and sunscreen with an SPF of 45-50 should be used to reduce skin damage. Sunglasses should also be used if there is sensitivity to sunlight. Children with Albinism should have follow up care from dermatologists and ophthalmologists.

Prognosis

The prognosis for Albinism is excellent. Life expectancy is the same as the general population, but the need for appropriate ophthalmologic and skin care is life-long. Though vision is decreased, it does not worsen over time. Careful sun protection should minimize the risk of skin cancer.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

Natalie’s Way Foundation
This organization was founded by parents of a child with Albinism. It aims to raise funding for further research on Albinism and vision-related disorders.

The National Organization for Albinism and Hypopigmentation (NOAH)
This website has a great amount of information for people with Albinism, including health-related and social issues, an updated calendar with nationwide events, and an online support group. There is also a long list of links to other websites.

The Vision of Children
This organization’s mission is to raise awareness about vision-related disorders. There are several personal stories from families with children with vision-related disorders, an email-network for families, and updates about research developments.

Google Search for Albinism

References and Sources

Boissy RE and Nordlund JJ (2003). Albinism. www.emedicine.com/derm/topic12.htm King RA (2002). Oculocutaneous Albinism Type 1. www.geneclinics.org/profiles/oca1 King RA and Oetting WS (2003). Oculocutaneous Albinism Type 2. www.genetests.org/profiles/oca2 Rosenberg T and Schwartz M (2004). Ocular Albinism, X-Linked. www.genetests.org/profiles/x-oa