Talk:Albinism in humans/Humans draft

Albinism (from Latin albus; extended etymology), more technically hypomelanism or hypomelanosis, is a form of hypopigmentary congenital disorder, characterized by a lack of melanin pigment in the eyes, skin and hair (or more rarely the eyes alone). Albinism results from inheritance of recessive genes. The word "albino" (noun and adjective), is sometimes used in a derogatory way towards people; more neutral terms are "albinistic" (adjective) and "person with albinism" (noun).

Causes
Albinism is a genetic disorder; it is not an infectious disease and cannot be transmitted through contact, blood transfusions, etc. The principal gene which results in albinism prevents the body from making the usual amounts of the pigment melanin. Most forms of albinism are the result of the biological inheritance of genetically recessive alleles (genes) passed from both parents of an individual, though some rare forms are inherited from only one parent. There are other genetic mutations which are proven to be associated with albinism. All alterations, however, lead to changes in melanin production in the body.

Albinism used to be 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.

The chance of children with albinism resulting from the pairing of one parent with albinism and one without albinism is low, as discussed in more detail below. However, because people can be carriers of genes for albinism without exhibiting any traits, albinistic children can be produced by two non-albinistic parents. Albinism usually occurs with equal frequency in both genders. The only exception from this is ocular albinism, because it is passed on to children through X-linked inheritance. Thus, males more frequently have ocular albinism.

Because people with albinism have skin that lacks (sufficiently or entirely) the dark pigment melanin, which helps protect the skin from ultraviolet radiation coming from the sun, they can sunburn easily from overexposure. (See human skin color for more information). Lack of melanin in the eye also results in problems with vision, related and unrelated to photosensitivity, which are discussed further below.

The albinistic are generally (but see related disorders below) as healthy as other humans. , with growth and development occurring as normal, and albinism by itself does not cause mortality (though the lack of pigment is an elevated risk for skin cancer, etc.) Humans with albinism commonly have vision problems and need sun protection, but also face a social challenge, as the condition is often a source of discrimination against them. About 1 in 17,000 human beings have some type of albinism, although up to 1 in 70 are carriers of albinism genes. While some of the very rare albinism disorders that are coupled with deafness and immunodeficiency appear to be linked with inbreeding, the vast majority of sufferers of common albinism are not the product of such unions; the more usual albinism genes are widespread enough that they can easily produce albinistic offspring from parents that are not related. Genetic testing can confirm albinism and what variety it is, but offers no medical benefits except in the cases of non-OCA disorders (see below) that cause albinism along with other medical problems (which may be treatable). Albinism itself cannot be treated.

Symptoms and conditions associated with albinism
Eye conditions common in albinism may or may not include:


 * Nystagmus, irregular rapid movement of the eyes back and forth, or in circular motion.
 * Strabismus, eye misalignment ("crossed eyes" or "lazy eye").
 * Refractive errors such as myopia or hyperopia and especially astigmatism are more likely
 * Photophobia, hypersensitivity to bright light and glare.
 * Foveal hypoplasia, underdevelopment of the fovea, the center of the retina
 * Optic nerve hypoplasia, underdevelopment of the optic nerve
 * Abnormal decussation (crossing) of the optic nerve fibers in the optic chiasm
 * Amblyopia, decrease in acuity of one or both eyes due to poor transmission to the brain, often due to other conditions such as strabismus

People with albinism usually have impaired vision due to one or more of the listed conditions. While a person with albinism may suffer from common refractive errors like nearsightedness or farsightedness, the visual problems particularly associated with albinism arise from a poorly-developed retinal pigment epithelium (RPE) due to the lack of melanin. This degenerate RPE causes foveal hypoplasia (a failure in the development of normal foveae), which results in eccentric fixation and lower visual acuity, and often a minor level of strabismus. Nystagmus is usually seen, as is photophobia or light sensitivity (see below).

The iris is a sphincter with pigmented tissue (which also makes up the color of the eyes) that contracts to limit the amount of light that can enter through the pupil and relaxes again to allow for better vision in darkness. This mechanism can be observed in humans and mammals (like in cat's eyes) and is needed because too much light is uncomfortable or even painful and decreases vision. In people with albinism, the iris does not have enough pigment to block the light, thus the decrease of pupil diameter is only partially successful in reducing the amount of light that enters the eye. . Additionally, the improper development of the RPE, which in normal eyes absorbs most of the reflected sunlight, further increases glare due to light scattering within the eye. The resulting sensitivity (photophobia) generally leads to a dislike of and discomfort in bright light, but does not prevent people with albinism enjoying the outdoors, especially when using sunglasses and/or brimmed hats.

The lack of pigment makes the skin very sensitive to sunlight and thus susceptible to sunburn, so people with albinism should either avoid prolonged exposure to bright sunlight or protect their skin.

Types of human albinism
There are two main categories of albinism in humans. Oculocutaneous albinism involves the skin, hair and eyes, whereas ocular albinism mainly affects the eyes with minimal to no skin involvement.

Oculocutaneous albinism

There are approximately ten different types of oculocutaneous albinism, which is mostly an autosomal recessive disorder. Certain ethnicities have higher incidences of different forms. For example, the most common type, the OCA2 (or tyrosinase positive) albinism, is especially frequent among people of indigenous African descent. It is an autosomal recessive disorder characterized by a congenital reduction or absence of melanin pigment in the skin, hair and eyes. The estimated frequency of OCA2 among African-Americans is 1 in 10,000, which contrasts with a frequency of 1 in 36,000 in white Americans. In some African nations, the frequency of the disorder is even higher, ranging from 1 in 2,000 to 1 in 5,000. Oculocutaneous albinism and deafness occur together in Waardenburg syndrome, predominantly observed among Hopi American Indians. The incidence of albinism in Hopi Indians has been estimated as approximately 1 in 200 individuals. The Hermansky-Pudlak Syndrome (HPS), an inherited disease which results in oculocutaneous albinism, is with approximately 1 in 2700 most prevalent among people of Puerto Rican origin, and is associated with mortality beyond melanoma-related deaths. "Mortality also is increased in patients with Hermansky-Pudlak syndrome and Chediak-Higashi syndrome. Patients with Hermansky-Pudlak syndrome have a bleeding diathesis secondary to platelet dysfunction and also experience restrictive lung disease, inflammatory bowel disease, cardiomyopathy, and renal disease. Patients with Chediak-Higashi syndrome are susceptible to infection and also can develop lymphofollicular malignancy."

Another form of oculocutaneous albinism, the "yellow oculocutaneous albinism", appears to be more prevalent among the Amish. People with this IB variant of the disorder commonly have white hair and skin at birth, but rapidly develop normal skin pigmentation in infancy.

Ocular albinism

Ocular albinism affects not only eye pigmentation, but visual acuity, as well. People with albinism typically test poorly, within the 20/60 to 20/400 range. While oculocutaneous albinism affects both sexes equally, ocular albinism is a disease primarily of males because of its sex-linked transmission.

Treatment of the symptoms
Albinism is a condition that cannot be "cured" or "treated" per se, but small things can be done to improve the quality of life for those affected. Most importantly to improve vision, protect the eyes from bright lights, and avoid skin damage from sunlight. The extent and success rate of these measures depend on the type of albinism and severity of the symptoms, as people with ocular albinism are likely to have normally pigmented skin, and thus do not need to take special precautions against skin damage.

Surgical treatment
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 foveas, 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).

Vision aids
Glasses and other vision aids, large-print materials and closed captioning, as well as bright but angled reading lights, can help individuals with albinism, even though their vision cannot be corrected completely. Some albinistic people do well using bifocals (with a strong reading lens), prescription reading glasses, and/or hand-held devices such as magnifiers or monoculars. Contact lenses may be colored to block light transmission through the iris. 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 states of the USA allow the use of bioptic telescopes for driving. (See also NOAH bulletin "Low Vision Aids".)

Although still disputed among the experts, many ophthalmologists recommend the use of glasses from early childhood onward to allow the eyes the best development possible.

Optometrists or ophthalmologists who are experienced in working with low vision patients can recommend various optical aids. Clinics should provide aids on trial loan, and provide instruction in their use. The American Foundation for the Blind maintains a directory of low vision clinics.

Sun protection
It is vital that people with albinism use sunscreen when exposed to sunlight to prevent premature skin aging or skin cancer. This poses a problem for those who cannot afford sunscreen, especially in regions with high exposure to sunlight, as in Africa. Special sun protective clothing and swimsuits are available and are a good alternative to excessive use of sunscreen.

Use of sunglasses and hats with wide brims can make the glare outside bearable. Other things that can help people with albinism are avoiding sudden changes of the lighting situation (switching the light on in complete darkness), using dimmable switches and adding tint to car windows or blinds to normal windows. Lights should be yellowish rather than blue and not point towards the usual position of a person with albinism (like their seat at a table). When possible, people with albinism generally prefer to have the light on their backs rather than face it.

Myths and superstitions
Albinistic individuals in Africa have sufferred discrimination and many are treated like outcasts. Due to albinism's effect on one's outward appearance, cultures around the world have developed many myths and superstitions regarding people with albinism:


 * A common misconception is that albinistic individuals are sterile; they are in fact fully capable of reproducing.
 * Folklore has developed in Zimbabwe that having sex with a woman with albinism will cure a man of HIV. This has led to many women with albinism in the area being raped (and thus infected) by HIV-positive men.
 * In Jamaica, people with albinism were historically degraded, and regarded as "cursed". In recent times, the albinistic musicians "King Yellowman" and "Prince Yellowman" (see below) have helped to curb this stereotype.
 * In some cultures, people with albinism are thought to have magical powers or to be able to tell the future, a common theme in fiction as well (see Albinism in popular culture for examples).
 * It is also thought by many that people with albinism live short life spans. This is not true in general, but may be a distorted view of a more reasonable fact that people with albinism have a higher risk of skin cancer if they do not use proper skin protection when in the sun. (Some very rare variants of albinism are lethal by adulthood or sooner, but they are so little-known by the general public that they are unlikely to have contributed to this myth.)

In popular culture
Portrayals of people with albinism in literature and films are rarely positive. This fact is sometimes referred to as the evil albino stereotype, or albino bias. The main article provides a list of negative, neutral and positive portrayals, a general discussion of the trend and its exceptions, and detail on fictional characters.

Famous people with albinism

 * Pierre Bourgault, Québécois politician (This is disputed: there are pictures taken circa 1960 that show him with dark hair and dark eyebrows, but possibly the result of dye.)
 * Brother Ali, a hip hop emcee from Minneapolis, Minnesota
 * Connie Chiu, photo model for Jean-Paul Gaultier
 * Cano Estremera, Puerto Rican salsa musician
 * Edward the Confessor, King of England (1042 - 1066)
 * Tony Evans, American newspaper columnist
 * Winston Foster (also known as "King Yellowman"), Jamaican dancehall musician
 * Brooke Fox, American singer-songwriter
 * Helder Gomes, civil rights advocate
 * G. Harishankar, Carnatic khanjira drummer (Multiple sources say he had albinism, though photos show him with dark hair, presumably dyed. Video footage shows him with pale skin and white eyebrows.)
 * Rebeca Soto Healy, socialite heiress of the Mexican newspaper El Imparcial
 * Pedro Julio-Hughes, Puerto Rican artist and falconer
 * Stanley Kaoni (also known as "Sataan"), former Solomon Islander militant leader (Kaoni has light blonde hair and pale facial skin with some evidence of vitiligo, and appears to have developed some pigmentation especially on the arms; his particular type of albinism is likely to be OCA1b.) [[Image:Stanley_Sataan_Kaoni.jpg|thumb|right|Stanley "Sataan" Kaoni, 2002]]
 * Salif Keita, Malian popular musician
 * Krondon, underground rapper from south-central Los Angeles, California.
 * Li Yipeng, Lee Hsien Loong's son
 * Malford Milligan, blues musician from Texas
 * Corrie Moodie (also known as "Al Beeno" and "Prince Yellowman"), Jamaican dancehall musician
 * Mem Nahadr, (a.k.a. "M") American performance artist, composer and jazz vocalist
 * Hermeto Pascoal, Brazilian jazz musician
 * T.K. Radhakrishnan, Carnatic flutist
 * Piano Red, American blues musician
 * Nestor Sánchez, Cuban singer
 * Seinei, 22nd Emperor of Japan (5th century)
 * Ali Şengöz, Turkish radio DJ
 * William Archibald Spooner, Anglican priest
 * Victor Vernado, African American stand-up comedian and actor.
 * Levan Wee, lead singer of Ronin, a Singaporean band.
 * Redford White, Filipino actor and comedian
 * Edgar Winter and Johnny Winter, American blues-rock musician brothers
 * David Wrench, Welsh-born electronic musician

People commonly mistaken to have albinism

 * Roy Orbison
 * Anthony Rapp is not albinistic; he just happens to be somewhat pallid, and plays in a band called Albinokid.
 * German singer Heino does not have albinism, but Graves disease.

Albinism support organizations

 * Positive Exposure &mdash; Non-profit organization founded by photographer Rick Guidotti, "dedicated to celebrating the spirit of difference". Focuses on genetic conditions, especially albinism.
 * Hermansky-Pudlak Syndrome Network (US-based)
 * NOAH &mdash; National Organization for Albinism and Hypopigmentation (USA); also has an online support group
 * International Albinism Center (research project based at the University of Minnesota, USA)
 * Albinism Fellowship (UK and Ireland)
 * AFA &mdash; Albinism Fellowship of Australia
 * TAF &mdash; The Albino Foundation (Nigeria & USA)
 * ALBA &mdash; Asociación de Ayuda a Personas con Albinismo &#91;Aid Association to Persons with Albinism&#93; (Spain)
 * OLA &mdash; Organización Latinoamericana de Albinismo &#91;Latin-American Albinism Organization&#93; (Mexico)

Other

 * "Albinism" - Geneva Foundation for Medical Education and Research
 * Albinism in Popular Culture website
 * "Pale Riders Who Wear Black Hats" - Wired News article on albinism in cinema
 * "The Golden Child: People of African Ancestry with Albinism"
 * Biblical references - William Blake's "Ancient of Days" was based upon the "Revelation of John", 1:14: "His head and hair were white like wool, as white as snow, and His eyes like a flame of fire"
 * Portraits of people with albinism by Pieter Hugo
 * People with albinism from Zimbabwe