What makes people albinos

Over the years, researchers have used various systems for classifying oculocutaneous albinism. In general, these systems contrasted types of albinism having almost no pigmentation with types having slight pigmentation. In types with slight pigmentation, hair appears more yellow or has a reddish tinge and vision may be better. DNA tests can determine the precise type of albinism. Research on albinism genes is ongoing.

Some are further divided into subtypes. This enzyme helps the body to change the amino acid, tyrosine, into pigment. There are two subtypes of OCA1. In OCA1A, the enzyme is inactive and no melanin is produced, leading to white hair and very light skin.

People with OCA2 make a minimal amount of melanin pigment and can have hair color ranging from very light blond to brown. People with OCA3 can have substantial pigment. They have reported mutations on three additional causative genes. As gene testing becomes available, and more people with these types of albinism are identified, the complete range of physical manifestations will be recognized, and may overlap with other known types of OCA.

Currently, these types of albinism are considered to be uncommon. Researchers have also identified several other genes that result in albinism with other features.

In addition to albinism, HPS is associated with bleeding problems and bruising. Some forms are also associated with lung and bowel disease. HPS is a less common form of albinism but should be suspected if a person with albinism shows unusual bruising or bleeding or if a genetic test for a type of OCA produces inconclusive results. Autosomes 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 and the many genes on them — one inherited from our father, the other inherited from our mother. That means that most types of albinism result from inheriting an albinism trait from both the mother and the father who often have typical pigmentation.

In this case, the mother and father are considered to be carriers of the albinism trait because they each carry a recessive gene for the condition but do not manifest the condition themselves. 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.

Ocular albinism OA1 is caused by a change in the GPR gene that plays a signaling role that is especially important to pigmentation in the eye. OA1 follows a simpler pattern of inheritance because the gene for OA1 is on the X chromosome. Females have two copies of the X chromosome while males have only one copy and a Y chromosome that makes them male. To have ocular albinism, a male only needs to inherit one changed copy of the gene for ocular albinism from his carrier mother.

Their health is rarely affected, but they have one mutated gene recessive gene and one normal gene dominant gene for the condition. Several genes provide 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, hair and eyes. Albinism is caused by a mutation in one of these genes. Different types of albinism can occur, based mainly on which gene mutation caused the disorder. The mutation may result in no melanin at all or a significantly reduced amount of melanin. Types of albinism are classified based on how they're inherited and on the gene that is affected. People with albinism have skin that is very sensitive to light and sun exposure.

Sunburn is one of the most serious complications associated with albinism because it can increase the risk of developing skin cancer and sun damage-related thickening of the skin.

Some people with albinism may experience discrimination. The reactions of other people to those with albinism can often have a negative impact on people with the condition. People with albinism may experience bullying, teasing or probing questions about their appearance, eyewear or visual aid devices. They usually look very different from members of their own families or ethnic groups, so they may feel like outsiders or be treated like outsiders. These experiences may contribute to social isolation, poor self-esteem and stress.

If a family member has albinism, a genetic counselor can help you understand the type of albinism and the chances of having a future child with albinism. He or she can also explain the available tests.

Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. This content does not have an English version. This content does not have an Arabic version. Overview The term albinism typically refers to oculocutaneous ok-u-low-ku-TAY-nee-us albinism OCA — a group of inherited disorders where there is little or no production of the pigment melanin.

Request an Appointment at Mayo Clinic. Autosomal recessive inheritance pattern Open pop-up dialog box Close. Autosomal recessive inheritance pattern To have an autosomal recessive disorder, you inherit two mutated genes, one from each parent. These subdivisions include :. X-linked ocular albinism: This is caused by a gene mutation of the X chromosome. X-linked ocular albinism mainly affects males. Vision problems are present, but eye, hair, and skin color is generally in the normal range.

Hermansky-Pudlak syndrome: This rare variant is most common in Puerto Rico. The symptoms are similar to oculocutaneous albinism but bowel, heart, kidney, and lung diseases or bleeding disorders, such as hemophilia and more likely, too. Symptoms are similar to oculocutaneous albinism but hair can appear silvery, and the skin can look slightly gray. There may be defects in the white blood cells, making infections more common.

As research continues, more specific mutations may be discovered, helping us understand the underlying causes of albinism in more detail. Most types of albinism are inherited in an autosomal recessive inheritance pattern. The exception is X-linked ocular albinism. This is passed on in an X-linked inheritance pattern. With autosomal recessive inheritance, an individual must receive faulty copies of a gene from the mother and father to develop albinism.

The parent who carries the gene often does not show symptoms. If both parents carry the gene but have no symptoms, there is a 1 in 4 chance that their offspring will have albinism. An estimated 1 in 70 people carry the genes associated with albinism but are not affected by the mutations.

Because females carry two X chromosomes, if one gene damaged, the other can often make up the shortfall. Females can still carry and pass on the gene. Men, however, have one X and one Y chromosome. This means that any albino mutations in their singular X chromosome will generate the condition. If the mother has an X-linked mutation, each daughter will have a 1 in 2 chance of becoming a carrier and each son will have a 1 in 2 chance of developing albinism.

Other diseases can also cause changes in pigmentation, but they will not cause changes in vision. If pigment changes and vision changes are both present, albinism is very likely to be the cause. The most reliable way to diagnose albinism is with genetic testing. However, in families with a history of albinism, this is not always necessary. Procedures to minimize strabismus can make it less noticeable, but surgery will not improve vision. The level of success in reducing symptoms varies between individuals.

Albinism does not worsen with age. A child with albinism can flourish and achieve the same education and employment as a person without the condition.