Albino disease. Albinism - causes and symptoms, diagnosis and treatment of albinism. Biochemical and genetic factors influencing the development of albinism

It happens that a baby is born with a very unusual appearance. His blond hair, skin and eyes attract the attention of others, raise many questions. Although in the modern world almost everyone has heard about such a phenomenon as albinism, there are many myths and unfounded prejudices around the disease. Parents of "special" babies need to know what manifestations, in addition to external ones, this disease leads to, and how to prevent the development of dangerous complications of the disease.

Pediatrician, neonatologist

The concept of albinism combines a group of hereditary pathologies in which there is a lack or absence of melanin pigment in the skin, hair, and iris.

According to statistics, among Europeans, the disease is found in one baby out of 37,000 newborns; among representatives of the Negroid race, this figure reaches 1: 3,000. In general, worldwide data on the incidence of the disease vary from 1:10,000 to 1:200,000. But the highest incidence of albinism is found among American Indians.

Kuna Indians are the indigenous inhabitants of the coast of Panama, their number does not exceed 50,000 people. The tribe still retained the old traditions and culture, and lives almost isolated from the rest of the world. Every 150th representative of the nationality is sick with albinism, which confirms the hereditary mechanism for the transmission of the disease.

The concept of "albino" comes from the Latin word albus, which means "white". The term was first introduced by the Filipino poet Francisco Baltazar, thus calling the "white" Africans. The writer mistakenly believed that the unusual skin color of these people was due to marriage with Europeans.

Mentions of mysterious people can be found in the history of almost every country, but the attitude towards them was very different. Misunderstanding of the problem led to various reactions of the population to albinos, ranging from worship and attribution of magical properties to complete rejection, demonstrating pathology in traveling circuses.

In African countries, the life of people with a hereditary syndrome remains difficult to this day. Some tribes consider the birth of an albino to be a curse, others attribute the magical, healing properties of its flesh, therefore innocent people are often killed.

In the modern world, more loyalty is shown to albinos. With the development of television, the problems of people with unusual appearances have become well known. There are many famous and talented people among albinos: actors, singers, models (Dennis Hurley, Sean Ross, Connie Chiu, Diandra Forrest).

Why does the disease occur?

The disease is hereditary with an autosomal recessive mechanism of transmission. Although the disease is rare, the albinism gene is found in every 70th inhabitant of the planet, but does not cause any external manifestations. In situations where both parents have this feature, the combination of their genetic information can lead to the birth of a baby with albinism. The development of the disease is not related to the sex of the child, the disease is equally common in boys and girls.

The name "melanin" itself comes from the Greek word melanos, which means black. This substance is capable of imparting a dark color to the tissues of a living organism, but its properties do not end there. Due to the presence of pigment, a protective function is carried out, melanin is a kind of protector, protects tissues from the harmful effects of ultraviolet rays, carcinogenic and mutagenic factors.

The hereditary defect leads to a violation of the metabolism of the amino acid tyrosine, which is involved in the formation and deposition of the melanin pigment. Pathological changes can be located on different chromosomes and be of different severity, so the manifestations of albinism are somewhat different. This feature is the basis for the classification of the disease.

Classification and features of manifestations of albinism

Oculocutaneous albinism (OCA) type 1

This disorder is associated with a mutation of the tyrosinase gene on chromosome 11 and leads either to a decrease in the formation or to the complete absence of tyrosine (an amino acid necessary for the synthesis of melanin pigment). Depending on the severity of the HCA defect divided into:

This is the most severe form of GCA, and is caused by the absolute inactivity of the tyrosinase enzyme, which leads to the complete absence of the melanin pigment. Signs of this form can be detected immediately after the birth of the baby, the crumbs are born with white hair and skin, a light blue iris. The characteristic appearance makes it possible to immediately suspect a hereditary disease in an infant.

As the baby grows older, the characteristic signs of the disease do not change. The child is not able to sunbathe, delicate skin is very prone to burns due to the complete absence of melanin. The risks of developing skin cancer are very high, so children should avoid being in the sun and use special protective equipment.

On the skin of people with this form of the disease, there are no moles, areas of pigmentation, but pigmentless nevi may appear, looking like an asymmetric light spot with clear edges.

The iris of an infant's eye is usually a very light, blue color, but in bright light it can appear red. This is due to the translucence of the blood vessels of the fundus through the transparent media of the eye.

Often the baby has such vision problems, astigmatism, strabismus, nystagmus, which appear immediately after birth or during life. And the phenomena of photophobia are very characteristic of this particular form of the disease.

The lack of melanin is manifested by a violation of visual function, and there is a relationship between pigment concentration and visual acuity. In the complete absence of melanin, the severity of visual pathologies is maximum.

The tyrosinase enzyme functions in the body of a sick child, but its activity is reduced, so a small amount of melanin is formed in the baby. Depending on the severity of the gene defect, the concentration of the produced pigment also changes. The manifestations of the disease vary, and the skin can have a different color, ranging from an almost normal skin color to inconspicuous pigmentation.

Babies are born without signs of the presence of melanin in the tissues, but over time there is some darkening of the skin, the appearance of pigmented and non-pigmented nevi. Changes in the skin often occur under the influence of sunlight, signs of sunburn appear, but the risk of developing skin cancer remains high.

Babies' hair becomes yellowish over time, and areas of brown pigmentation appear on the iris. Visual impairment is also present in children with this form of the disease.

temperature sensitive type

This form of the disease belongs to the type 1B type, in which the activity of tyrosinase is changed. The enzyme acquires temperature sensitivity and begins to work actively in areas of the body with a lower temperature. Patients with this form of the disease are born with white skin, lack of pigmentation in the iris and hair.

Over time, there are signs of darkening of the hairline on the arms and legs, but in the armpits and on the head they remain light. Due to the higher temperature of the eyeballs, compared with the skin, in children with this type of disease, pathologies of the organs of vision are significantly pronounced.

Oculocutaneous albinism type 2

This type of disease is the most common worldwide. Unlike type 1 GCA, the mutation is located on the 15th chromosome, and the resulting defect does not impair tyrosinase activity. The development of albinism in GCA type 2 is due to the pathology of the P-protein, a violation of tyrosine transport.

In the case of the development of GCA type 2, babies of the European race are born with external signs typical of albinos - white skin, hair, light blue iris. Therefore, it is sometimes difficult to distinguish which type of disease the pathology in a child belongs to. With age, there is some darkening of the hair, the color of the eyes changes. The skin usually remains white and is not capable of tanning, but under the influence of sunlight, age spots and freckles appear on it.

The manifestations of GCA type 2 in representatives of the Negroid race are different. These babies are born with yellowish hair, pale skin, and blue irises. Over time, there is an accumulation of melanin, the formation of nevi, age spots.

It happens that albinism is combined with other hereditary diseases, for example, with Prader-Willi syndromes, Angelman, Kallman and others. In such cases, signs of diseases of various organs come to the fore, and the lack of melanin is a concomitant pathology.

Oculocutaneous albinism type 3

In this case, the mutation develops in the TRP-1 gene, which occurs only in African patients. The body of a sick baby is able to produce a brown pigment, not a black one, melanin, which is why the disease is also called "red" or "red" HCA. At the same time, the color of the skin and hair of the albino remains brown for life, and the damage to the visual function is moderately expressed.

Ocular albinism associated with a mutation in the X chromosome

Sometimes manifestations of a lack of pigment are found mainly in the organ of vision, this happens with ocular types of albinism. Mutation of the GPR143 gene, located on the X chromosome, leads to impaired visual function, refractive errors, nystagmus, and iris transparency.

At the same time, the patient's skin is practically not changed, some blanching is possible in comparison with the color of the skin of peers.

Since the mutation is associated with the X chromosome, the disease manifests itself only in boys. Girls are asymptomatic carriers of this mutation, and have only minor abnormalities in the form of increased transparency of the iris and spots on the fundus.

Autosomal recessive ocular albinism (ARGA)

Manifestations of this disease are equally common in boys and girls, and eye manifestations prevail in the clinical picture. However, at present, ARGA has not been linked to any particular mutation, and different patients have different chromosome defects. There is a theory that this disease is an ocular form of GCA types 1 and 2.

Pigmentation disorders are not always distributed evenly throughout the body. Sometimes children have partial albinism ("piebaldism"). This kind of pathology manifests itself already at birth, the baby has depigmented areas on the skin of the trunk and limbs, white strands of hair. The disease is inherited in an autosomal dominant manner from parents and usually does not bring health problems, damage to internal organs.

The first signs of the disease can be detected after the birth of the baby, since the appearance of such children has characteristic features. To clarify the diagnosis, the doctor conducts a survey of the parents of a small patient in order to detect hereditary risk factors for the development of albinism.

Consultations with an ophthalmologist, dermatologist and geneticist provide grounds for making a preliminary diagnosis, determining the type of albinism. You can accurately establish the pathology using genetic diagnostic tests, DNA testing.

Determination of tyrosine activity in tissues is an effective method for identifying the type of albinism and predicting the disease, but its use is limited due to the high cost of the study.

Treatment and prognosis of albinism

There is no specific treatment for the disease, parents of special children should accept this feature of the child and help him prevent complications of the disease. An insufficient amount of melanin in the tissues makes the child too susceptible to sunlight, increases the risk of skin cancer and retinal detachment.

Photophobia is very characteristic of this disease, so babies need special high-quality sunglasses. Before going outside, the child must use sunscreen for the skin, wear hats.

The baby must be registered with an ophthalmologist, dermatologist, regularly undergo examinations and follow all medical recommendations. Often children need vision correction with the help of special glasses and contact lenses. Subject to these rules, a patient with a hereditary disease lives a long and fulfilling life.

African countries are considered the most unsuitable place for albinos to live. The scorching sun and the lack of qualified medical care leads to loss of vision and the development of skin cancer in 70% of sick people.

Myths about albinism

The unusual disease has a long history. Although people's awareness of this disease is growing, misconceptions persist. stereotypes about this disease.

1. All albinos have red eyes.

Some parents believe that in order to make a diagnosis of albinism, a red tint of the baby's eyes must be present. But this is a delusion, the color of the iris can be different: from light blue to gray and even purple. This symptom depends on the form of the disease. The eyes acquire a red tint under certain lighting, when the vessels of the fundus become visible through transparent media.

2. Albinos don't have melanin, they can't sunbathe.

In some cases, there is a small amount of melanin in the tissues of special children, and tanning can occur when exposed to ultraviolet rays. But such experiments are dangerous for the health of the crumbs, because the risk of developing skin cancer remains high in any case. A sick child has to constantly use special sunscreen.

3. White hair is a constant sign of albinism.

The hair color of children with hereditary pathology can be different: white, straw yellow, light brown. Often, with the growth of the baby, external manifestations change, moderate pigmentation of the tissues occurs.

But still, children with albinism differ markedly in appearance from their peers.

4. All albinos will eventually become blind.

Although the pathology of the organs of vision is very characteristic of this genetic disease, ophthalmic problems rarely lead to blindness. Indeed, children with albinism almost always need vision correction with glasses and contact lenses, but if the necessary measures are taken, visual function will not be lost.

5. Babies with a hereditary disease lag behind in development.

The lack or absence of melanin does not affect the mental development of the baby. Sometimes there is a combination of albinism with other genetic syndromes, which are accompanied by damage to internal organs, a decrease in intellectual and mental development.

But the pathology of melanin synthesis in such cases is secondary.

6. Albinos can't see in the dark.

Due to the lack of a protective pigment in the iris, it is difficult for albino to be outdoors, they develop photophobia. In darkened rooms or in cloudy weather, it is easier for children to see the world around them. But do not forget that special children almost always suffer from visual impairment, the manifestations of which do not depend on the illumination of the room.

Albino people are outlandish and unusual personalities for our society, meeting with whom always leaves a feeling of some mystery, the presence of something otherworldly and incredible.

External signs of albinos

According to external signs, these people are distinguished by a transparent-pale skin color, too sensitive to sunlight, colorless eyelashes and snow-white hair.

The reason for this anomaly lies in the absence of melanin in the body - a special protective enzyme. For this reason, the skin of albinos is exposed to the merciless effects of sunlight, which can cause many dangerous diseases. This deviation, laid down at the genetic level, can be either partial (with selective spotting of the skin) or complete, which is most often found among the Indians of Mexico, Arizona, North American blacks and residents of Sicily. Manifested at birth, albinism remains in a person's life forever.

In addition to having too light skin, the eyes of an albino human are numbing with their redness. From a scientific point of view, this oddity can be explained by rays of light refracted at a certain angle passing through the red eye vessels. In fact, most of these strange people have gray or light blue eyes, less often purple and green.

Causes of albinism

The causes of albinism are:

heredity;
complications after illness.

This anomaly is divided into 10 groups, the most common of which are I and II.

Albino people of group I are characterized by white hair and skin. In this regard, they have a high risk of getting skin cancer. Another hallmark of people in this category is poor eyesight. Their eyes are constantly twitching.

Albinos of group II have a skin color from yellowish to pink, with age it brightens.

Physical features of mysterious people

Albinos often have very weak immunity, and unusual appearance is not the only thing that distinguishes them from the rest. There are a number of properties inherent in these outlandish representatives of mankind.

They do not tolerate daylight, for which they are considered accomplices of dark forces. Albinos - people whose reasons for existence are laid down at the genetic level, have nothing to do with otherworldly forces. Lack or absence of pigment in the pupil leads to defective vision, so many of them are not even able to drive.

Along the way, insufficient vision entails complications such as:

photophobia - fear of light;
astigmatism - a violation of the shape of the lens, cornea and eye;
tremor - shaking of the head.

Consequences of albinism

If the anomaly manifests itself in a severe form, then strabismus, myopia (nearsightedness) and a significant decrease in vision (up to its loss) may occur. Albinos already by the age of 18 see only 20%. Quite often, people with red eyes (albinos) become victims of an erroneous diagnosis by doctors who reveal atrophy of the optic nerve in patients due to the similarity of symptoms: pale fundus and poor vision. In most cases, atrophy in patients is not confirmed.

In addition to the fact that albinos do not see well, they also have hearing problems. In such people, there is a violation of blood clotting and short stature. Studies conducted in Tanzania have shown that all albino children have skin defects in the first year of life; There is one cancer for every 9-year-old child. Less than 2% of albinos live up to 40 years in Tanzania.

Treatment of albinism

The treatment of albinism is unsuccessful, since it is impossible to compensate for the lack of melanin and prevent visual impairment. The patient is advised to avoid being in the sun, to use all kinds of protective equipment when going outside. Sometimes surgical intervention is applicable to restore the oculomotor muscles with existing strabismus. Forming pathological transformations of the retina and optic nerve usually cannot be eliminated.

Who are albinos?

So, who are these incomprehensible and mysterious people - albinos? What is the nature of their origin? Why are albinos born?

The concept of "albino" was introduced into our vocabulary by the Portuguese Francisco Baltazar, the founder of Philippine literature, mistakenly considering "white Africans" as the result of marriages between Europeans and the local population. Although the Europeans themselves learned about albinos from the stories of the Spanish knight Hernan Fernando Cortes, who lived in the 15th century, after his trip to North America. The latter claimed that the palace of Emperor Montezuma had a special room for "white creatures" who were sacrificed to the gods during solar eclipses. Nobody wanted to admit that albinos are people! Photos and other images of these unfortunates have been preserved for us by history.

One English pirate, whose name remained unknown, in his memoirs described the impressions of a long stay on the Isthmus of Panama, where he had the opportunity to meet people with an unusual milky-white skin color. This impressed the Englishman so much that he turned to the leader of the tribe with a question about the unusual appearance of these people. The answer received sounded mystical and spoke of the power of imagination of the expectant mother, who at the moment of conception looks at the moon.

Myths about albino people

The existence of these anomalous people in nature is surrounded by a sufficient number of myths, according to which albinos are:

the result of a curse;
infectious carriers of the disease. Since ancient times, albinos have been avoided, trying to keep a distance from them; children with signs of albinism were often not accepted into schools and were not allowed to play with their peers;
sterile (incapable of having children);
lagging behind in development.

Albinos - a gift from heaven

Albinos have always been such intriguing personalities that they were endowed with all sorts of magical properties. It was believed that these creatures can predict the future, fly through the air, sleep with their eyes open, while remembering and seeing everything that happens around, read the thoughts of strangers, turn water into blood, destroy at a distance. In the eyes of those around them, they were angels who descended to earth, able to heal with just one touch and able to read other people's thoughts.

In society, albino people were so outlandish that they even served as exhibits in traveling circuses, causing various reactions from others: from absolute rejection to the deepest admiration. Albinos are beautiful people, it's hard not to notice them in the crowd. They easily captivate with some deep inner magnetism. But often they are afraid, disguising fear under ridicule. And this makes people suffering from albinism feel excluded from society, loneliness and rejection.

Hunting for albino people

Albinos are people! Photos demonstrate that they are radically different from others, but this is not a reason to mock or discriminate against them. Unfortunately, this was not always the case. In the Middle Ages, they were declared assistants of the devil and burned at the stake.

Representatives of the African population were confident in the miraculous properties of various parts of the body of albinos (including the most sought after - the genitals). With the help of them, they hoped to get good luck and wealth, to be cured of various diseases, and therefore hunted "white people" in every possible way. On the black market for one hand, which is deprived of a black albino, you can get more than 1 thousand dollars, which is slightly more than the annual salary of the inhabitants of this country.

The blond hair of an albino woven into fishing nets is considered an effective bait when catching fish. The earth, sprinkled with the ashes of albinos burned at the stake, according to some beliefs, will itself begin to bring gold to the surface and indicate the location of the gold-bearing vein. The African belief that the albino Negro dissolves in the air after death forces the curious to test this in practice and pushes them to commit a crime against a harmless person.

The bloody hunt for albinos was practically not punished; at best, they were considered "missing". But the atrocities in Tanzania have forced local authorities to at least start taking action to protect the country's unusual residents. The first trial took place in 2009. For the murder and molestation of a 14-year-old boy, his punishers were hanged. But the bloodhunters simply invented more sophisticated methods of hunting. Now they began to simply cut off the limbs of their victims, leaving them alive. The last 3 years have been sad for 90 albinos, who were deprived of arms and legs by the killers.

Protection of albino people

The modern world has changed little in the lives of these mysterious people: they are still outcasts for society; an albino black born into a black family is considered inferior from the very moment of birth. Even today, the poor are forced to hide in guarded boarding houses, specially created for their protection. This is especially true for Africa, in particular Tanzania, in which more than 20 people have become victims of superstition in recent years. Albinos are forced to create public organizations aimed at protecting against discrimination and prejudice against the unusual color of the skin and blond hair. The governments of a number of countries, trying to support albinos, provide them with humanitarian assistance and sponsor research work. In countries with a hot climate, there is an active promotion of measures to prevent skin cancer. Albinos are advised to use sunglasses, sunscreen, wear long sleeves; children under 3 years of age are generally advised to avoid exposure to sunlight as much as possible.

In Africa, it is planned to establish a network of clinics that will provide counseling services to parents who have had albino children in parallel with the provision of medical care. In Tanzania, such clinics have already been established.

In the United States, the Organization of Representatives of Albinism and Hypopigmentism (OPAG), otherwise the Union of the Colorless, is fighting for the rights of albinos. Annual conferences are held at which all the hardships and difficult moments of the life of people in this category are discussed.

Statistics

According to the average data, one albino is born for every 20 thousand people. If we consider this issue from a territorial point of view, we can observe that albinism is most common among the indigenous inhabitants of the Panama coast - the Kuna Indians, whose total number is about 50 thousand people. For every 150 people they have 1 albino. This is the highest rate in the world. It is interesting to note that in fact the albinism gene is quite common in society: every 70th is its hidden carrier.

Most often, albinos (the people whose photos are presented in the article are their brightest representatives) are born to Africans. In addition to genetic congestion, this can also be explained by marriages between relatives characteristic of Africa. If parents have different types of albinism, then there is a chance of having a normal healthy child.

Albinism includes a group of hereditary disorders that are characterized by minimal production of the pigment melanin.

The type and amount of melanin produced by the human body determines the color of the skin, hair and eyes. Most people with albinism are sensitive to sun exposure and are at increased risk of developing skin cancer.

Parents should surround the child with albinism with love and attention and protect from peer attacks. Albinos are prone to stress, depression and psychosis.

Causes of albinism

Albinism occurs in humans due to the absence or blockade of the tyrosinase enzyme. It is extremely important for the production of melanin (the name comes from the Greek word "melanos", which means "black" in Russian). Skin color is determined by the amount of melanin in it. The more it is, the darker the skin color. In cases where problems with the production of tyrosinase are not observed, the cause of albinism is considered to be a mutation in the genes.

Albinism is inherited from parents. It appears in a child if both parents are carriers of the defective gene. When the defective gene is present in only one parent, children do not develop albinism, but the mutated gene still remains in the body, which can be passed on to the next generation. This whole process is called autosomal recessive inheritance.

Features of the disease

Albinism is represented by a congenital pathology. This disease occurs equally often in boys and girls.

Its occurrence is provoked by the lack of blockade of the tyrosinase enzyme. Tyrosinase regulates the synthesis of a special pigment - melanin on such parts of the body as the dermis, hair, iris. Pathology can be complete, partial.

Usually albinos are not much different from ordinary people (in the field of development), but cases are not excluded when such people have pathologies:

infertility;
mental retardation;
impaired visual acuity.

What is most interesting, this disease is considered to occur on all continents, in different ethnic groups. It is classified as a hereditary pathology.

The first signs of albinism, photo

From birth, albino people have little or no pigment in their skin, eyes, and hair (ocular albinism) or only in their eyes (ocular albinism). The degree of pigmentation in each case varies. Some people develop slight pigmentation in their hair or eyes as they age. Others develop colored freckles on their skin. Individuals with a complete lack of melanin are called albinos. Albinoids are people with very little melanin. But one cannot help but pay attention to the vision and skin problems common among albinos.

Skin problems. The dark pigment melanin helps protect the skin from the ultraviolet radiation of sunlight. Albinos do not have this pigment, so their skin is extremely sensitive to direct sunlight. Precautions must be taken to avoid skin burns, namely the use of sunscreen, be sure to wear hats and special clothing.
Vision problems. They arise due to the pathological development of the retina (hypoplasia of the fovea) and abnormal systems of nerve communication between the eye and the brain: a complete optic chiasm, while normal - partial. With albinism, nystagmus and transparency of the iris, as well as decreased visual acuity, strabismus, impaired binocular vision, increased sensitivity to light exposure - photophobia can be detected.

People with albinism are quite pale, with very fair hair and discolored eyes. Sometimes their eyes even turn red or purple, depending on the amount of pigment. This is due to the fact that there is practically no color in the iris, and the eyes appear pink or red due to the vessels inside the eye translucent through the iris. However, people with albinism are otherwise as healthy as the rest of the population.

How is the diagnosis carried out?

The process of diagnosing albinism includes the following activities:

External examination of the patient;
Study of changes in pigmentation;
Conducting a detailed eye examination;
Collection of family history.

An ophthalmologist must be consulted during the examination. This helps to identify changes such as strabismus, photophobia, nystagmus (involuntary movements of the eyeballs). In albinism, both eyes are always affected. If the examination reveals changes in only one eye, other diagnostic options should be considered.

There is a technique for determining the presence of a defective gene that causes albinism. Carrying out such an analysis allows you to identify some forms of the disease even before the birth of the child. The study of chorionic villi allows you to recognize signs of gene mutation in the fetus as early as the fifth week of pregnancy.

Treatment of albinism

When albinism is detected, there is no specific treatment today, only preventive measures have been developed to improve the patient's quality of life. To maintain the existing level of vision, it is necessary to protect the eyes from sunlight - this is achieved by wearing special sunglasses or contact lenses.

Exposure to bright sun should be avoided or the skin should be protected with special creams and lotions. If you follow these recommendations, then in general the prognosis of albinism is favorable - patients can live a long and fulfilling life. At the same time, regular consultations with a dermatologist and an ophthalmologist are necessary to prevent complications, such as skin cancer or retinal detachment.

Preventive measures

You can help a child or relative with albinism by teaching them the rules of self-help, namely:

be sure to use a sunscreen with a sun protection factor of at least 30, both from UVA and UVB rays;
avoid being in the sun during peak heat (from 11 a.m. to 4 p.m.);
it is necessary to use means that increase the sharpness of vision (glasses, special magnifiers, monoculars);
clothing should be closed - shirts with sleeves, long skirts or dresses, trousers, hats with a brim, sunglasses;
protect your eyes from ultraviolet radiation, for example, wear tinted glasses or transitional lenses that darken in bright light.

There is only one way to prevent the development of mountaineering. It consists in conducting a genetic study of a couple planning a pregnancy. Modern methods make it easy to detect the presence of defective genes and assess the risk of having a child with such a pathology.

In humans, albinism is inherited as an autosomal recessive trait.

In humans, albinism is inherited as an autosomal recessive trait, and color blindness is inherited as an X-linked trait. Determine the genotypes of the parents, as well as the possible genotypes and phenotypes of the offspring and their percentage from the marriage of a heterozygous for the first sign of a healthy woman who does not carry the gene for color blindness, and men who are color blind and albino. What laws of inheritance will appear in this case?

A - normal pigmentation
a - albino
X (B) - normal vision
X (c) - color blindness

According to the condition, the mother is heterozygous for the albinism gene and has normal vision - AaX (B) X (B)

a color-blind and albino man aaX(v)Y
♂aaX (c) Y x ♀AaX (B) X (B) \u003d AaX (B) Y - boy with normal pigmentation, normal vision, aaX (B) Y - albino boy, normal vision, AaX (B) X (c) - a girl with normal pigmentation, normal vision, aaX (B) X (c) - an albino girl, normal vision.

The laws of inheritance of the sex-linked and splitting are manifested.

Full or partial albinism in humans is not a disease. However, such a person cannot be called absolutely healthy either, because albinism is the absence or a very small amount of melanin, which leads to the risk of various diseases.

Melanin in the body of an ordinary person tints his skin, hair, cornea. People deprived of this substance look accordingly - white colorless eyes, skin and hair. What causes this condition and is there a way to deal with it? After all, even if the health of such a person is normal, the social component of his life leaves much to be desired.

Full or partial albinism, this is a mutation of one of the genes responsible for the production of melanin. Moreover, one gene is responsible for eye color, others for hair and skin color. And the mutation of one of them leads to partial or complete albinism.

If the albinism is not complete, the person has a chance to pass on the full version of the mutation to their children. The fact is that albinism is transmitted from generation to generation not only as a dominant gene, but also as a recessive one, that is, it can manifest itself in any case. Further, partial albinism may arise as an independent mutation and in no way be associated with previous generations.

In addition, partial albinism is determined by the amount of melanin in the body. If it is not present at all, then this is a manifestation of complete albinism. If some part of it is still present in the skin or eyes, or hair, then such albinism is called incomplete.

Symptoms of albinism

This phenomenon was perceived differently in different countries. Somewhere, they were afraid of albinos and burned them at the stake, but somewhere they bowed before them and were still afraid. For a long time, people guessed that it was a disease or a syndrome; albinism has been a mysterious phenomenon for centuries.

But to date, numerous studies have made it possible to classify this syndrome and even define it into groups.

So, the complete absence of melanin in the body is called complete or oculocutaneous albinism. There is also a group of people related to partial albinism or otherwise - eye. To understand how one type of syndrome differs from another, it makes sense to consider both in more detail.

Complete or oculocutaneous albinism

A symptom of such a disease is snow-white skin, light iris and milky hair. Such people have red eyes, which is characterized by the absence of an iris and the ability of light to shine through the eye, making visible the blood vessels around the eyeball.

People with this form of albinism are extremely sensitive to sunlight, it causes them a painful burn of the skin. They are forced to hide in the shade all their lives and wear tight clothes covering their limbs and, most importantly, their heads. Vision in complete albinos, as a rule, is weakened, plus they have nystagmus, this is an involuntary twitching of the eyeball.

This type of albinism does not always manifest itself throughout a person's life. It happens that over the years, as you grow older, the body begins to produce more and more tyrosinase, and therefore melanin. In this regard, the skin acquires its characteristic shade, freckles may appear, the iris darkens and becomes brown, the hair becomes yellowish. That is, albinism is still present, but not as pronounced as in childhood.

Oculocutaneous albinism in black people can manifest itself in a rather strange way. The fact is that in this case, melanin is produced in humans, but not black, but brown. In this regard, the Negro is born with red hair and blue eyes.

This type of albinism is diagnosed by a simple external examination of the newborn. After all, from the first days he has vivid signs of this syndrome.

Partial, ocular albinism

This type of pathology is reflected only in the eyes. The skin has a normal color and easily tolerates the sun, and the hair can be of a wide variety of shades characteristic of the ethnic group of a person. The eyes also have a number of characteristic manifestations of albinism.

An albino of this type may have poor eyesight, strabismus, photophobia, involuntary twitching of the eyeball. The iris is much more transparent than normal, has a gray tint. In addition, such people are not able to see the same object with both eyes, that is, binocular vision is impaired.

This type of albinism is diagnosed by an external examination of the eyes, as well as an analysis of the content of tyrosinase in the body, usually the hair follicle is studied for this. Sometimes DNA analysis allows you to determine albinism. In this case, it is appropriate to find out if there was a relative with a similar syndrome in the person's family.

In addition, it can be noted that sometimes albinism is part of other syndromes. For example, Klein-Waardenburg, Chedak-Higashi, Mende, Cross-McKusick-Brin, Tietze, Hermansky-Pudlak. The manifestations of albinism in these syndromes may be the following; a lock of blond hair in a hairstyle, a spot of dark color on the face or other part of the body.

Treatment of albinism

Today, albinism is considered incurable. All types of therapy in this case are aimed at correcting the manifestations of pathology, that is, symptomatic. In this regard, the need for treatment is more of an aesthetic nature, since albino attracts a lot of attention and in some societies, with a high level of xenophobia, causes antipathy.

For the treatment of myopia caused by albinism, laser vision correction is used. The same procedure is used to correct strabismus.

To protect the eyes from the bright sun, an albino is recommended to wear sunglasses at all times. The clothes of such people should be a set that completely hides the skin. The face should also be protected from the sun. If albinism is not pronounced, then taking beta-carotene can give the skin a yellowish tint.

Otherwise, an albino must rely on his mental stability, especially in a society that is biased against people with such defects. In this regard, an albino may need the help of a professional psychologist, especially in adolescence, when the psyche is most vulnerable.

Complications of albinism

Complications from albinism can be both physical and emotional. Physical complications include various skin diseases caused by exposure to direct sunlight. It can be a common burn or an oncological disease. A complication with vision, it can eventually deteriorate so badly that complete blindness occurs. Although very few such cases are known.

Emotional complications include chronic stress and depression caused by the negative attitude towards the albino by the people around him. In severe cases, this condition can result in a suicide attempt, especially from adolescence, when mental instability and maximalism prevail in the child. Therefore, people with a weak psyche are constantly monitored by a doctor, correcting their well-being according to indications, sometimes even with the help of medications.

Preventive actions

Since this state of the human body is transmitted at the gene level, it is currently impossible to prevent it. And if the parents are albinos, they are waiting for offspring, then most likely their children will be the same, you need to be emotionally prepared for this. Genetic engineering cannot yet change the configuration of DNA and RNA protein chains. If only one of the parents is a carrier of a mating gene, then the probability of having an albino child is 50 to 50, which also does not interfere with preparing for this psychologically.

Incredible Facts

Although people with albinism are often teased or ridiculed, people don't know much about the condition.

16. In some cultures, albino animals are highly revered. So, Native Americans revere white bison as a symbol of strength and good luck, protecting them from attacks.

Albinism gene

17. Approximately 1 in 70 people is a carrier of the albinism gene. If both parents have the albinism gene, there is a 25 percent chance of having a child with albinism.

18. For an albino child to be born, he must have faulty genes from both parents. If a child inherits one normal gene and one albinism gene, the normal genes will produce enough melanin.

19. One of the most serious types of albinism is known as Germansky-Pudlak syndrome. People with this disorder are prone to bleeding, bruising, and lung disease.

20. Vitiligo- another skin disorder associated with albinism, in which only certain areas of the skin lose pigment. Famous people with vitiligo: Michael Jackson and model Winnie Harlow.

21. Albinism is most common among various peoples in central and western Africa. Some evolutionary biologists believe that when we switched from primates to hominids and lost most of our hair, the skin underneath the hair was pale. People who produced more melanin (with dark skin) were thought to have an evolutionary advantage.