Alternative Names:achromia, achromasia, or achromatosis
Albinism is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of an enzyme involved in the production of melanin. Albinism results from inheritance of recessive gene alleles and is known to affect all vertebrates, including humans. The most common term used for an organism affected by albinism is “albino”. Additional clinical adjectives sometimes used to refer to animals are “albinoid” and “albinic”.
Albinism is associated with a number of vision defects, such as photophobia, nystagmus and astigmatism. Lack of skin pigmentation makes the organism more susceptible to sunburn and skin cancers.
Several different genes are involved in albinism, depending on the specific type of the condition.
Classification in humans:
There are two main categories of albinism in humans:
*In oculocutaneous albinism Types 1-4 with different levels with pigmentation (despite its Latin-derived name meaning “eye-and-skin” albinism), pigment is lacking in the eyes, skin and hair. (The equivalent mutation in non-humans also results in lack of melanin in the fur, scales or feathers.) People with oculocutaneous albinism can have anything from no pigment at all to almost normal levels.
*In ocular albinism, only the eyes lack pigment. People who have ocular albinism have generally normal skin and hair color, although it is typically lighter than either parent. Many even have a normal eye appearance. Also, ocular albinism is generally sex-linked, therefore males are more likely to be affected. Males are without another X chromosome to mask recessive alleles on the X they inherit.
Other conditions include albinism as part of their presentation. These include Hermansky-Pudlak syndrome, Chediak-Higashi syndrome, Griscelli syndrome, Waardenburg syndrome, and Tietz syndrome. These conditions are sometimes classified with albinism. Several have sub-types. Some are easily distinguished by appearance, but in most cases genetic testing is the only way to be certain.
Albinism was formerly categorized as tyrosinase-positive or -negative. In cases of tyrosinase-positive albinism, the enzyme tyrosinase is present. The melanocytes (pigment cells) are unable to produce melanin for any one of a variety of reasons that do not directly involve the tyrosinase enzyme. In tyrosinase-negative cases, either the tyrosinase enzyme is not produced or a nonfunctional version is produced. This classification has been rendered obsolete by recent research.
About one in 17,000 children in the UK is born with some type of albinism.It affects people from all races and its frequency across the human population is estimated to be approximately 1 in 20,000.
People with albinism are born with little or no pigmentation in their eyes, skin and hair (oculocutaneous albinism) or sometimes in the eyes alone (ocular albinism). But the degree of pigmentation varies (especially in oculocutaneous albinism) and some people gain a little pigmentation in their hair or eyes with age, or develop pigmented freckles on their skin.
Apart from their physical appearance, people with the condition can experience a number of associated problems, depending on which genetic type they have.
Although the most recognizable form of albinism results in milky white skin, skin pigmentation can range from white to nearly the same as parents or siblings without albinism.
For some people with albinism, skin pigmentation never changes. For others, melanin production may begin or increase during childhood and adolescence, resulting in slight changes in pigmentation. With exposure to the sun, some people may develop:
Hair color can range from very white to brown. People of African or Asian descent who have albinism may have hair color that is yellow, reddish or brown. Hair color may also change by early adulthood.
Eye color can range from very light blue to brown and may change with age.
The lack of pigment in the colored part of your eyes (irises) makes them somewhat translucent. This means that the irises can’t completely block light from entering the eye. Because of this translucence, very light-colored eyes may appear red in some lighting. This occurs because you’re seeing light reflected off the back of the eye and passing back out through the iris again — similar to red eye that occurs in a flash photograph.
Signs and symptoms of albinism related to eye function include:
*Rapid, involuntary back-and-forth movement of the eyes (nystagmus)
*Inability of both eyes to stay directed at the same point or to move in unison (strabismus)
*Extreme nearsightedness or farsightedness
*Sensitivity to light (photophobia)
The cause of albinism is a mutation in one of several genes. Each of these genes provides the chemically coded 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 production at all or a significant decline in the amount of melanin.
In most types of albinism, a person must inherit two copies of a mutated gene — one from each parent — in order to have albinism. If a person has only one copy, then he or she won’t have the disorder.
Impact of mutations on eye development
Regardless of which gene mutation is present, vision impairment is a common characteristic with all types of albinism. These impairments are caused by irregular development of the nerve pathways from the eye to the brain and from abnormal development of the retina.
Types of albinism
The system for classifying types of albinism is based primarily on which mutated gene caused the disorder rather than how it’s manifested. Nonetheless, most types of albinism have some features that distinguish them from each other. Types of albinism include:
*Oculocutaneous albinism. Oculocutaneous albinism is caused by a mutation in one of four genes. These mutations result in signs and symptoms related to vision (ocular) and those related to skin (cutaneous), hair and iris color.
Oculocutaneous albinism 1 is caused by a mutation in a gene on chromosome 11. Most people with this type of albinism have milky white skin, white hair and blue eyes at birth. Some people with this disorder never experience changes in pigmentation, but others begin to produce melanin during childhood and adolescence. Their hair may become a golden blond or brown. Their skin usually doesn’t change color, but it may tan somewhat. The irises may also change color and lose some of their translucence.
Oculocutaneous albinism 2 is caused by a mutation in a gene on chromosome 15. It’s more common in Sub-Saharan Africans and African-Americans than in other population groups. The hair may be yellow, auburn, ginger or red, the eyes can be blue-gray or tan, and the skin is white at birth. In people of African descent, the skin may be light brown, and in those of Asian or Northern European descent, the skin is usually white. In either case, the skin color is generally close to the family’s coloring, but little bit lighter. With sun exposure, the skin may over time develop freckles, moles or lentigines.
Oculocutaneous albinism 3 (rare cases) is caused by a gene mutation on chromosome 9 and has been primarily identified in black South Africans. People with this disorder usually have reddish-brown skin, ginger or reddish hair, and hazel or brown eyes.
Oculocutaneous albinism 4, caused by a gene mutation on chromosome 5, is a rarer form of the disorder generally presenting signs and symptoms similar to those of type 2. This type of albinism may be one of the most common forms among people of Japanese 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 the developmental and functional vision problems of albinism. But 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 one of at least seven mutated genes. People with this disorder have signs and symptoms like those of oculocutaneous albinism, but they also develop lung and bowel diseases and a bleeding disorder.
*Chediak-Higashi syndrome. Chediak-Higashi syndrome is a rare form of albinism caused by a mutation in a gene on chromosome 1. Signs and symptoms are also similar to those of 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 with white blood cells that results in a susceptibility to infections.
Complications of albinism include physical risks as well as social and emotional challenges.
*In physical terms, humans with albinism commonly have vision problems and need sun protection. But they also face social and cultural challenges (even threats) as the condition is often a source of ridicule, discrimination, or even fear and violence. Cultures around the world have developed many beliefs regarding people with albinism. This folklore ranges from harmless myth to dangerous superstitions that cost human lives. Cultural challenges can be expected to be vastly higher in areas where pale skin and light hair stand out more from the ethnic majority’s average phenotype.
*In African countries such as Tanzania and Burundi, there has been an unprecedented rise in witchcraft-related killings of albino people in recent years. This is because albino body parts are used in potions sold by witchdoctors. Numerous authenticated incidents have occurred in Africa during the 21st Century. For example, in Tanzania, in September 2009, three men were convicted of killing a 14-year-old albino boy and severing his legs in order to sell them for witchcraft purposes. Again in Tanzania and Burundi in 2010, the murder and dismemberment of a kidnapped albino child is reported from the courts, as part of a continuing problem.
*Other examples: In Zimbabwe, belief that sex with an albinistic woman will cure a man of HIV has led to rapes (and subsequent HIV infection).
*Certain ethnic groups and insular areas exhibit heightened susceptibility to albinism, presumably due to genetic factors (reinforced by cultural traditions). These include notably the Native American Kuna and Zuni nations (respectively of Panama and New Mexico); Japan, in which one particular form of albinism is unusually common; and Ukerewe Island, the population of which shows a very high incidence of albinism.
All of these factors may contribute to social isolation, poor self-esteem and stress.
There’s no cure for albinism, but treatments and aids can help the symptoms and reduce the risk of damage to the skin and eyes.
For the most part, treatment of the eye conditions consists of visual rehabilitation. Surgery is possible on the ocular muscles to decrease nystagmus, strabismus and common refractive errors like astigmatism. Strabismus surgery may improve the appearance of the eyes. Nystagmus-damping surgery can also be performed, to reduce the “shaking” of the eyes back and forth. The effectiveness of all these procedures varies greatly and depends on individual circumstances. More importantly, since surgery will not restore a normal RPE or foveae, surgery will not provide fine binocular vision. In the case of esotropia (the “crossed eyes” form of strabismus), surgery may help vision by expanding the visual field (the area that the eyes can see while looking at one point).
Glasses and other vision aids, large-print materials and CCTV, as well as bright but angled reading lights, can help individuals with albinism, even though their vision cannot be corrected completely. Some people with Albinism do well using bifocals (with a strong reading lens), prescription reading glasses, and/or hand-held devices such as magnifiers or monoculars (a very simple telescope). Contact lenses may be colored to block light transmission through the iris. But in case of nystagmus this is not possible, due to the irritation that is caused by the movement of the eyes. Some use bioptics, glasses which have small telescopes mounted on, in, or behind their regular lenses, so that they can look through either the regular lens or the telescope. Newer designs of bioptics use smaller light-weight lenses. Some US states allow the use of bioptic telescopes for driving motor vehicles.
Although still disputed among the experts, many ophthalmologists recommend the use of spectacles from early childhood onward to allow the eyes the best development possible.
People with Hermansky-Pudlak and Chediak-Higashi syndromes usually require regular specialized care to prevent complications.
Home Remedies & Lifestyle
You can help your child learn self-care practices that should continue into adulthood:
*Use low-vision aids, such as a hand-held magnifying glass, a monocular or a magnifier that attaches to glasses.
*Apply sunscreens with a sun protection factor (SPF) of at least 30 that protects against both UVA and UVB light.
*Avoid high-risk sun exposure, such as being outside in the middle of the day, at high altitudes and on sunny days with thin cloud cover.
*Wear protective clothing, including long-sleeved shirts, long pants and broad-rimmed hats.
*Protect your eyes by wearing dark, UV-blocking sunglasses.
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.
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- A Creepy Monster of the Forest: The Albino, Vampiric Redwood Tree | Discoblog (blogs.discovermagazine.com)
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