Albinism is caused by a mutation in one of several genes. Each of these genes provides instructions for making one of several proteins involved in the production of melanin. Melanin is produced by cells called melanocytes, which are found in your skin and eyes. A mutation may result in no melanin at all or a significant decline in the amount of melanin.
In some types of albinism, a person must inherit two copies of a mutated gene — one from each parent — in order to have albinism (recessive inheritance).
Impact on eye development
Regardless of which gene mutation is present, vision impairment is a key feature of all types of albinism. These impairments are caused by irregular development of the optic nerve pathways from the eye to the brain and from abnormal development of the retina.
Types of albinism
Types of albinism, based mainly on which mutated gene caused the disorder, include:
Apr. 19, 2014
Oculocutaneous albinism. Oculocutaneous (ok-u-low-ku-TAY-nee-us) albinism is caused by a mutation in one of four genes. People with oculocutaneous albinism (OCA) type 1 have milky white skin, white hair and blue eyes at birth. Some people with OCA type 1 never experience an increase in pigmentation, but others begin to produce melanin during early childhood. Their hair may become a golden blond, brown or red, and their irises may change color and lose some translucence.
OCA type 2 is most common in sub-Saharan Africans, African-Americans and Native Americans. The hair may be yellow, auburn, ginger or red, the eyes can be blue-gray or tan, and the skin is white at birth. With sun exposure, the skin may, over time, develop freckles, moles or lentigines.
People with OCA type 3, mainly found in black South Africans, usually have reddish-brown skin, ginger or reddish hair, and hazel or brown eyes. OCA type 4 looks similar to type 2 and is most often found in people of East Asian descent.
- X-linked ocular albinism. The cause of X-linked ocular albinism, which occurs almost exclusively in males, is a gene mutation on the X chromosome. People who have ocular albinism have vision problems, but their skin, hair and eye color are generally in the normal range or slightly lighter than that of others in the family.
- Hermansky-Pudlak syndrome. Hermansky-Pudlak syndrome is a rare albinism disorder caused by a mutation in one of at least eight different genes. The disorder is much more common in Puerto Rico. People with this disorder have signs and symptoms similar to people with oculocutaneous albinism, but they may also develop lung and bowel diseases, or a bleeding disorder.
- Chediak-Higashi syndrome. Chediak-Higashi syndrome is a rare form of albinism associated with a mutation in the LYST gene. With signs and symptoms similar to oculocutaneous albinism, the hair is usually brown or blond with a silvery sheen, and the skin is usually creamy white to grayish. People with this syndrome have a defect in white blood cells that increases their risk of infections.
- Wolff K, et al. Fitzpatrick's Dermatology in General Medicine. 8th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. www.accessmedicine.com/resourceTOC.aspx?resourceID=740. Accessed Nov. 21, 2013.
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- Levin AV, et al. Albinism for the busy clinician. Journal of AAPOS. 2011;1:59.
- What is albinism? National Organization for Albinism and Hypopigmentation (NOAH). http://www.albinism.org/publications/2010/What_is_Albinism.pdf. Accessed Nov. 21, 2013.
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- Brodsky MC (expert opinion). Mayo Clinic, Rochester, Minn. Dec. 15, 2013.
- Hand JL (expert opinion). Mayo Clinic, Rochester, Minn. Dec. 13, 2013.