Albinism

How common is albinism?

Approximately 1 in 17,000 people in Europe and the USA have one of the types of albinism, although in some parts of the world it is more common than this. In Tanzania 1 in 1,500 babies are born with albinism. Albinism can affect all races and also affects other species, such as mice.

Most children with albinism are born to parents who have normal hair and eye colour for their ethnic backgrounds.

What is a person with albinism like?

While most people with albinism have very light skin and hair, levels of pigmentation can vary depending on the type of albinism. Oculocutaneous albinism (OCA) involves the eyes, hair and skin. Ocular albinism (OA), which is much less common, involves only the eyes, while skin and hair may appear similar or slightly lighter than that of other family members.

People often suppose that people with albinism have white hair and white skin; however, this is not usually the case. A common myth is that they have red eyes; however, this is also not true. Most people with albinism have blue eyes and some have hazel or brown eyes. However, in certain light conditions there is a reddish tint reflected through the iris and pupil from the retina and the eyes appear red (similar to the 'red eye' in flash photography).

How is albinism inherited?

The genes for OCA are located on 'autosomal' chromosomes. These are the 22 pairs of chromosomes that contain genes for our general body characteristics, compared to the one pair of sex chromosomes.

We normally have two copies of these chromosomes - one inherited from our father, the other inherited from our mother. For a recessive condition (like most types of albinism) to occur, both of the person's chromosomes must carry that trait - that is, the one from the mother and the one from the father.

That means that most types of albinism result from inheriting an albinism gene from both the mother and the father (who often have normal pigmentation themselves, as their OTHER gene is normal). When both parents carry the albinism gene (and neither parent has albinism) there is a one in four chance at each pregnancy that the baby will be born with albinism.

If a parent has albinism then they will pass on one affected gene to their child. The child will still only develop albinism if they also inherit an albinism gene from the other parent.

What are the different types of albinism?

Over the years, researchers have used various systems for classifying oculocutaneous albinism (OCA). Some types of albinism have almost no pigmentation with other types having slight pigmentation. In less pigmented types of albinism, hair and skin are cream-coloured and vision is often in the range of 20/200 (severely visually impaired). In types with slight pigmentation, hair appears more yellow or has a reddish tinge and vision may be better.

Recent research has used analysis of DNA - the chemical that encodes inherited (genetic) information - to arrive at a more precise classification system for albinism. Albinism is divided into OCA (which is more common and has many forms) and ocular albinism (OA), which is rare.

Oculocutaneous albinism (OCA)
Seven forms of OCA are now recognised - OCA1, OCA2, OCA3, OCA4, OCA5, OCA6 and OCA7. Some are further divided into subtypes:

• OCA1 results from a genetic defect in an enzyme called tyrosinase. This enzyme helps the body to make melanin pigment. There are two subtypes of OCA1. In OCA1A, the enzyme is completely inactive and absolutely no melanin is produced, leading to white hair and very light skin. In OCA1B, the enzyme is minimally active and a small amount of melanin is produced. This leads to hair that may darken to blond, yellow/orange or even light brown, as well as slightly more pigment in the skin.

• OCA2, results from a genetic defect in a different protein that helps the tyrosinase enzyme to function. People with OCA2 make a tiny amount of melanin pigment and can have hair colour ranging from very light blond to brown.

• OCA3 is rare and results from a genetic defect in a related protein. People with OCA3 can have normal pigmentation.

• OCA4 results from a genetic defect in a protein that helps the tyrosinase enzyme to function. It is similar to OCA2.

• OCA5-7 were recognised in humans in 2012 and 2013. Currently, these types of albinism are considered to be uncommon.

Ocular albinism (OA)
OA, which is much less common, involves only the eyes, while skin and hair may appear similar or slightly lighter than that of other family members.

Researchers have also identified several other genes that result in albinism with other features. These include Hermansky-Pudlak syndrome (patients have albinism with bleeding problems and bruising). Other albinism-related syndromes include Chédiak-Higashi syndrome and Griscelli's syndrome.

How is albinism diagnosed?

Diagnosis is based on examination and observation. The only type of albinism with white hair at birth is OCA1.

Hair bulbs plucked from the scalp can be tested to check for the ability to make melanin. This can detect OCA type 1A but does not rule out other types of albinism.

The most accurate test is a genetic test. The test is useful only for families which contain people with albinism and even then, not all cases can be detected.

What problems do people with albinism have?

People with albinism typically experience vision problems, skin problems and social problems.

Vision problems

Eye specialists (ophthalmologists) and opticians (optometrists) can help people with albinism to compensate for their eye problems, although they cannot cure them.

Eye problems in albinism result from the abnormal development of the eye because of a lack of pigment. The most common ones include nystagmus (regular horizontal back and forth movement of the eyes), squint (muscle imbalance of the eyes), sensitivity to bright light and glare and problems with vision and focus..

People with albinism are sensitive to glare as extra light gets into their eyes through the thinner iris. However, they do not prefer to be in the dark, as they need light to see just like anyone else.

They may be either far-sighted or near-sighted and usually have astigmatism. Because the retina (the surface inside the eye that receives light) does not develop normally, the nerve pathways transmitting vision to the brain also don't develop normally.

Vision treatments

Treatment of albinism is mainly with support and help with vision:

Surgery can be used to correct squint, which may improve the appearance of the eyes. However, surgery cannot improve eyesight or depth (binocular) vision. Eye specialists usually start to treat squint in infants of about 6 months of age. They may recommend a patch over one eye, or the wearing of glasses.

Surgery can also help reduce nystagmus. People with albinism may find ways of reducing nystagmus while reading, such as placing a finger by the eye, or tilting the head at an angle where nystagmus is reduced.

Sunglasses or tinted contact lenses may help with light sensitivity. Indoors, it is important to place lights for close work over a shoulder rather than in front.

Some people with albinism use glasses which have small telescopes mounted on, in or behind their regular lenses (bioptics). This enables them to look through either the regular lens or the telescope. Some patients wear contact lenses with a special iris tint.

Various classroom aids help children with albinism
High-contrast written material with large text can help children to read: black on white high-contrast material is the easiest to read. Because children with albinism often have difficulty keeping track of their place on the page if copying text, it may help to allow them to write in the textbook. Audio tapes may be helpful. Computers with large text display will make reading easier.

Giving the child copies of the teacher's notes may be useful; sometimes magnifying devices can also be helpful.

Skin problems

People with albinism are very susceptible to burning and subsequent skin cancers. High-factor sun protection cream and avoidance of sunlight are essential. In tropical countries, people with albinism may not have access to adequate skin protection and may develop life-threatening skin cancers. They need to use sunscreens rated 20 SPF or higher, together with opaque clothing, in order to enjoy outdoor activities in summer.

Social difficulties

Children with albinism can experience difficulty with bullying and social relationships because their condition is so visible. They look different from their families, friends and other members of their ethnic group. In some ethnic groups the difference may be dramatic, especially within communities of colour, where the race or paternity may be questioned. Support of family and friends and contact with other affected people can be helpful.

In some countries such as China albinism is considered bad luck, leaving people with albinism ostracised and excluded from mainstream society.

What is the outlook (prognosis)?

Life expectancy is normal for a person with albinism. Although vision is usually severely impaired, intellect and development are normal.

People with albinism have an increased risk of sunburn and of skin cancers as their skin is not protected by pigment.

Can albinism be prevented?

Albinism cannot be prevented, as it is an inherited (genetic) condition rather than an illness.

Gene testing can be used to determine if a fetus has albinism. Amniocentesis is performed at 16 to 18 weeks of gestation in pregnancy. Those considering testing of this sort should be made aware that, whilst children with albinism are usually severely visually impaired, they function well and have a normal lifespan.

Dr Mary Lowth is an author or the original author of this leaflet.