Albinism in humans

Albinism is a hereditary disease associated with impaired pigment metabolism in the body. With this pathology, there is a shortage of melanin, a special substance that imparts color to the skin, pigment and iris, eyes, hair, nails. It would seem that such, if the matter is only in the color of the skin, eyes, hair? But not everything is so simple actually.

The absence or decrease of melanin content leads to the appearance of not only cosmetic defects, but also a number of health problems. In particular, it is intolerance to sunlight, impaired vision. Albinos have a higher risk of developing skin cancer. Albinism is not a disease that threatens the patient's life, but can significantly affect its quality. From this article you can learn more about what albinism is, why it arises, how it manifests in a person, and what is treated.

The causes of albinism

In humans, the color of the skin, hair, eyebrows, eyelashes, iris is determined by heredity. This means that each of us is born with the programmed color of the skin and its appendages, the color of the eyes. The true color of the skin is determined in areas that are not exposed to sunlight (buttock area). Albinism - is the result of gene disorders, and the most diverse. In the human body, there are several genes that determine the color of the above structures. Any mutation in at least one of them leads to a violation of the pigment content of melanin and, accordingly, to the occurrence of albinism. This means that albinism is a congenital disease, although not always immediately apparent. Albinism can be inherited by successive generations, both dominantly and recessively (that is, to manifest itself in all generations or only when two pathological genes coincide). The mutation itself can arise spontaneously, that is, in the absence of a similar problem in the genus.

Melanin (from the word "melanos", which means "black") is a substance that colors the skin in a certain color. The more melanin, the darker the color. The degree of melanin deficiency determines the severity of albinism. With total absence of pigment, albinism is complete. The formation of melanin depends on the enzyme tyrosinase (its content and activity are determined genetically). Under the influence of tyrosinase from tyrosine, melanin is formed in the cells of the skin and iris of the eye. Melanin protects a person from ultraviolet radiation by forming a tan. Melanin in the eye ensures the penetration of light only through the pupil, which allows us to look at the bright light painlessly, and also protects the eye from visible and long-wave part of radiant energy.

Albinism is a mysterious disease, enveloped in a myriad of myths. In countries where the level of education leaves much to be desired (for example, in Tanzania), local healers spread rumors about the danger to society of albino people. Because of this, albinos are persecuted, sometimes even their lives are in danger. In other countries, albinos are attributed supernatural abilities, in particular, medicinal. Objective medicine, of course, is far from these beliefs. In fact, albinos are ordinary people with little external features, and nothing more.

Symptoms

According to statistics, in the world, 1 person out of 17-1, 00 suffers from a kind of albinism. Why a species? Yes, because albinism is a heterogeneous disease. In medicine, it is common to distinguish two large clinical groups of this pathology:

• full albinism, or eye-dermal;
• partial albinism, or ophthalmic.

Full albinism develops in those cases when the genetic defect determines the content of melanin in the skin, and in the hair, and in the visual system. Partial albinism means a lack of melanin only in the visual system. In recent decades, it turned out that among the full and partial albinism there are several more varieties. Let us dwell on the main features of some of them.

Full, or eye-skin albinism

People with this type of albinism, from birth, have white skin (with a milky hue), white hair and blue irises. This is due to the complete absence of tyrosinase (or when its activity is zero).

Since the iris completely transmits light, the eye itself acquires a reddish or pink hue (due to translucent vessels), which forms the phenomenon of "red eyes". Due to the complete absence of pigment, the skin of such patients is not capable of fighting with ultraviolet radiation, sunburn is not formed. Under the influence of sunlight, people with eye-skin albinism immediately get burned. That is why they are forced to hide their skin with clothing with long sleeves, constantly wear trousers or long skirts, hats. These albinos have a significantly higher risk of developing skin cancer. The skin remains white throughout life, no pigmentation occurs. There is a tendency to the appearance of spider veins and keratosis. Usually the skin is dry, with low sweat production. The hair of albinos is thin and soft.

Eye manifestations are not only in the reddish tinge of the eyes. It is difficult for such people to bear bright light, therefore photophobia is characteristic of them. Visual acuity is usually reduced (and does not increase with age), often nystagmus is observed - vibrational involuntary movements of eyeballs.

There is a kind of eye-skin albinism, in which tyrosinase is not completely, but only partially (or its activity is reduced). In this case, incomplete albinism (albinoidism) develops. Clinically, this is manifested by a change in skin color from white (with a significant decrease in tyrosinase activity) to almost normal (with almost normal activity of the enzyme). At birth, these people have white skin, eyes with a reddish hue, hair without a pigment. However, as people grow older with this type of albinism, the skin darkens (and can light up a little), hair accumulates a yellow pigment. Iris is also pigmented: there is light or dark brown pigmentation, sometimes by patches, and not totally. In an adult with such a variety of albinism, the color of the eyes can be any, even dark-brown. So, not all albinos have red eyes, as is commonly believed. There may be freckles and pigmentation spots. With this kind of albinism, eyebrows and eyelashes have a darker color than the hair on the head. Visual acuity is reduced, but may increase with age (as the iris diminishes).

Another fairly common type of albinism among the African population is red-headed eye-skin albinism. In this case, the genetic defect determines the production of melanin is not black, but brown. In such patients, the skin is rusty or light brown, and the iris is brownish-blue.

Also known is another interesting variant of albinism - temperature-sensitive (heat-dependent). With this variety, tyrosinase is not active at body temperature above 37 ° C. This leads to the fact that in the "cold" parts of the body melanin is synthesized (hair on the head, arms and legs), and in the "warm" - no (armpits). Such people at birth have white skin, colorless hair (as the body temperature of infants is above 37 ° C). After the first year of life, the skin and hair gradually darken. Eyes have a body temperature above 37 ° С, therefore in them the pigmentation does not appear even in due course.

Partial, or ocular albinism

This form of albinism has clinical manifestations only from the side of the organ of vision. Skin pigmented normally, able to sunbathe. Hair is normal, both in color and in texture.

The main eye symptoms with this form of albinism are:

• decreased visual acuity;
• astigmatism;
• strabismus;
• photophobia;
• nystagmus;
• transparent iris (with a gray-blue or light-brown hue);
• violation of binocular vision (the ability to see one image with two eyes), amblyopia.

Separately, I would like to note that albinism can be a component of other diseases (for example, Chediak-Higashi syndrome, Germanic-Pudlac syndrome, and so on). In these cases, there are more gross genetic disorders that affect not only the genes responsible for the synthesis of tyrosinase, which leads to the emergence of a number of other symptoms (impaired immunity, problems with the kidneys and cardiac activity, etc.).

Diagnosis of albinism

Eye-skin albinism with a complete absence of tyrosinase can be suspected already at birth. Incomplete forms or ocular albinism are detected only in a complex examination: an ophthalmologist, a study of hair bulbs on tyrosinase, and DNA analysis will be required. The detected genetic defect in DNA diagnostics will put an end to the diagnostic process.

Treatment

Albinism, as a genetic disease, is classified as incurable. Existing methods of treatment are, in fact, symptomatic. They include:

• correction of visual acuity with the help of glasses or contact lenses;
• use of sunglasses when going out;
• Wearing clothes made of natural fabrics, covering the skin as much as possible, as well as using headdresses with wide margins;
• use of sunscreens and lotions regardless of the season;
• with incomplete albinism, beta-carotene can be used to give the skin a yellow hue (90-180 mg per day).

Currently, molecular genetics is developing methods of treatment to combat genetic mutations. Perhaps, when scientists can "repair" genes, eliminating mutations, albinism will pass into the category of radically curable diseases. But so far this is the prerogative of the future.

Thus, albinism is a genetic disease that can not be classified as severe or dangerous. Its main manifestations are disorders of pigmentation of the skin, hair and eyes. Albinism in no way affects life expectancy, does not lead to the development of complications from internal organs. This disease causes a person to change their lifestyle, avoid sunlight, constantly wear glasses, sometimes leads to depression (inadequate attitude of others). Albinism is not at all dangerous to others, but can be inherited. And a lot of myths associated with this mysterious disease are completely groundless.