What is Bombay Syndrome. Inheritance of blood groups. Bombay Phenomenon…. Significance of a high level in the definition of other diseases. Bombay phenomenon: why the child's blood type is not the same as that of the parents What is Bombay syndrome rare blood type

How it works (in terms of cell biochemistry)…

On the surface of our red blood cells there are carbohydrates - “H antigens”, they are also “0 antigens”.(On the surface of red blood cells there are glycoproteins that have antigenic properties. They are called agglutinogens.)

The A gene codes for an enzyme that converts some of the H antigens into A antigens.(Gene A encodes a specific glycosyltransferase that adds a residueN-acetyl-D-galactosamineto an agglutinogen, resulting in agglutinogen A).

The B gene codes for an enzyme that converts some of the H antigens into B antigens.. (Gene B encodes a specific glycosyltransferase that adds a residue D-galactose to agglutinogen to form agglutinogen B).

Gene 0 does not code for any enzyme.

Inheritance of blood groups. Bombay Phenomenon...

For example, we cross parents with groups 1 and 4 and see why they havethere can't be a child with 1

(Because a child with type 1 (00) should receive a 0 from each parent, but a parent with type 4 (AB) does not have a 0.)

Inheritance of blood groups. Bombay Phenomenon...

Bombay Phenomenon

Occurs when a person does not form the “initial” H antigen on erythrocytes. In this case, the person will not have either A antigens or B antigens, even if the necessary enzymes are present.

Example: a person with the AA genotype must have 2 blood groups. But if he is AAhh, then his blood type will be the first, because there is nothing to make antigen A from.

This mutation was first discovered in Bombay, hence the name. In India, it occurs in one person in 10,000, in Taiwan - in one in 8,000. In Europe, hh is very rare - in one person in two hundred thousand (0.0005%).

Inheritance of blood groups. Bombay Phenomenon...

An example of the Bombay phenomenon at work:if one parent has the first blood type, and the other has the second, then the child can't have the fourth group, because none of the

parents do not have the gene B necessary for group 4.

Polymerism…

Polymeria - the interaction of non-allelic multiple genes that unidirectionally affect the development of the same trait; the degree of manifestation of a trait depends on the number of genes. Polymeric genes are denoted by the same letters, and alleles of the same locus have the same subscript.

Polymer interaction of non-allelic genes can be

cumulative and non-cumulative.

With cumulative (accumulative) polymerization, the degree of manifestation of a trait depends on the total action of several genes. The more dominant alleles of genes, the more pronounced this or that trait. Splitting in F2 by phenotype during dihybrid crossing occurs in the ratio 1:4:6:4:1, and in general corresponds to the third, fifth (during dihybrid crossing), seventh (during trihybrid crossing), etc. lines in Pascal's triangle.

Polymerism…

With non-cumulative polymer, the signmanifests itself in the presence of at least one of the dominant alleles of polymeric genes. The number of dominant alleles does not affect the severity of the trait. Splitting in F2 by phenotype in dihybrid crossing - 15:1.

Polymer example- inheritance of skin color in humans, which depends (in the first approximation) on four genes with a cumulative effect.

If the child's blood type does not match one of the parents, this can be a real family tragedy, as the baby's father will suspect that the baby is not his own. In fact, such a phenomenon may be due to a rare genetic mutation that occurs in the European race in one person in 10 million! In science, this phenomenon is called the Bombay Phenomenon. In biology class, we were taught that a child inherits the blood type of one of the parents, but it turns out that this is not always the case. It happens that, for example, parents with the first and second blood groups, a baby is born with the third or fourth. How is this possible?

For the first time, genetics encountered a situation when a baby had a blood type that could not be inherited from its parents in 1952. The male father had I blood type, the female mother had II, and their child was born with III blood group. According to this combination is not possible. The doctor who observed the couple suggested that the father of the child did not have the first blood type, but its imitation, which arose due to some kind of genetic changes. That is, the gene structure has changed, and therefore the signs of blood.

This also applies to proteins responsible for the formation of blood groups. There are 2 of them in total - these are agglutinogens A and B located on the erythrocyte membrane. Inherited from parents, these antigens create a combination that determines one of the four blood groups.

At the heart of the Bombay phenomenon is recessive epistasis. In simple terms, under the influence of a mutation, the blood type has signs of I (0), since it does not contain agglutinogens, but in fact it is not.

How can you tell if you have the Bombay Phenomenon? Unlike the first blood group, when there are no agglutinogens A and B on erythrocytes, but there are agglutinins A and B in the blood serum, agglutinins determined by the inherited blood group are determined in individuals with the Bombay phenomenon. Although there will be no agglutinogen B on the child's erythrocytes (reminiscent of I (0) blood group), only agglutinin A will circulate in the serum. This will distinguish the blood with the Bombay phenomenon from the usual one, because normally people with group I have both agglutinins - A and B.

When a blood transfusion becomes necessary, patients with the Bombay Phenomenon should only be transfused with exactly the same blood. Finding it, for obvious reasons, is unrealistic, so people with this phenomenon, as a rule, save their own material at blood transfusion stations in order to use it if necessary.

If you are the owner of such a rare blood, be sure to tell your spouse about it when you get married, and when you decide to have offspring, consult a geneticist. In most cases, people with the Bombay phenomenon give birth to children with the usual blood type, but not in accordance with the rules of inheritance recognized by science.

Photos from open sources

A person with a blood type known as the Bombay phenomenon is a universal donor: his blood can be transfused to people with any blood type. However, people with this rarest blood type cannot accept any other type of blood. Why?

There are four blood types (first, second, third and fourth): the classification of blood groups is based on the presence or absence of an antigenic substance that appears on the surface of blood cells. Both parents influence and determine the child's blood type.

Knowing the blood type, a couple can predict the blood type of their unborn child using the Pannet lattice. For example, if the mother has a third blood type and the father has a first blood type, then most likely their child will have a first blood type.

However, there are rare cases when a couple has a child with the first blood group, even if they do not have the genes of the first blood type. If so, the child most likely has the Bombay Phenomenon, which was first discovered in three people in Bombay (now Mumbai) in India in 1952 by Dr. Bhende and his colleagues. The main characteristic of erythrocytes in the Bombay phenomenon is the absence of the h-antigen in them.

Rare blood group

h-antigen is located on the surface of erythrocytes and is a precursor of antigens A and B. The A-allele is necessary for the production of transferase enzymes that convert h-antigen into A-antigen. In the same way, the B allele is required for the production of transferase enzymes for the conversion of the h antigen to the B antigen. In the first blood type, the h-antigen cannot be converted because transferase enzymes are not produced. It is worth noting that the transformation of the antigen occurs by adding complex carbohydrates produced by transferase enzymes to the h-antigen.

Bombay Phenomenon

A person with Bombay phenomenon inherits a recessive allele for the h antigen from each parent. It carries a homozygous recessive (hh) genotype instead of the homozygous dominant (HH) and heterozygous (Hh) genotypes found in all four blood groups. As a result, the h-antigen does not appear on the surface of blood cells, so A and B antigens are not formed. The h-allele is the result of a mutation in the H-gene (FUT1), which affects the expression of the h-antigen in red blood cells. The scientists found that people with the Bombay Phenomenon are homozygous (hh) for the T725G mutation (leucine 242 changes to arginine) in the FUT1 coding region. As a result of this mutation, an inactivated enzyme is produced that is unable to form the h-antigen.

Antibody production

People with the Bombay phenomenon develop protective antibodies against the H, A, and B antigens. Because their blood produces antibodies against the H, A, and B antigens, they can only receive blood from donors with the same phenomenon. Blood transfusion of the other four groups can be fatal. In the past, there have been cases where patients with supposedly type I blood died in transfusions because doctors did not test for the Bombay Phenomenon.

Since the Bombay phenomenon is, it is very difficult for patients with this blood type to find donors. The chance of a donor with the Bombay phenomenon is 1 in 250,000 people. India has the most people with the Bombay phenomenon: 1 in 7600 people. Geneticists are convinced that a large number of people with the Bombay phenomenon in India are due to consanguineous marriages between members of the same caste. A one-blood marriage in a higher caste allows you to maintain your position in society and protect wealth.

August 15th, 2017

Who does not know that people have four main blood types. The first, second and third are quite common, the fourth is not so widespread. This classification is based on the content in the blood of the so-called agglutinogens - antigens responsible for the formation of antibodies.

The blood type is most often determined by heredity, for example, if the parents have the second and third groups, the child can have any of the four, in the case when the father and mother have the first group, their children will also have the first, and if, say, the parents have the fourth and the first, the child will have either a second or a third.

However, in some cases, children are born with a blood type that, according to the rules of inheritance, they cannot have - this phenomenon is called the Bombay phenomenon, or Bombay blood.

Within the ABO/Rhesus blood group systems that are used to classify most blood types, there are several rare blood types. The rarest is AB-, this type of blood is observed in less than one percent of the world's population. Types B- and O- are also very rare, each accounting for less than 5% of the world's population. However, in addition to these two main ones, there are more than 30 generally accepted blood typing systems, including many rare types, some of which are observed in a very small group of people.

There are three types of genes responsible for the blood group - A, B, and 0 (three alleles).

Every person has two blood type genes - one from the mother (A, B, or 0) and one from the father (A, B, or 0).

6 combinations are possible:

On the surface of our red blood cells there are carbohydrates - “H antigens”, they are also “0 antigens”. (On the surface of red blood cells there are glycoproteins that have antigenic properties. They are called agglutinogens.)

Bombay Phenomenon

H - gene encoding antigen H

h - recessive gene, antigen H is not formed

This mutation was first discovered in Bombay, hence the name. In India, it occurs in one person in 10,000, in Taiwan - in one in 8,000. In Europe, hh is very rare - in one person in two hundred thousand (0.0005%).

An example of how the Bombay phenomenon works #1: if one parent has the first blood type and the other has the second, then the child cannot have the fourth group, because neither parent has the B gene necessary for the 4th group.

And now the Bombay phenomenon:

And now the Bombay Phenomenon

Cis position A and B

In a person with the 4th blood group, an error (chromosomal mutation) can occur during crossing over, when both genes A and B are on one chromosome, and nothing is on the other chromosome. Accordingly, the gametes of such an AB will turn out strange: in one there will be AB, and in the other - nothing.

And now the mutation:

The probability of having children shaded in gray is, of course, less - 0.001%, as agreed, and the remaining 99.999% fall on groups 2 and 3. But still, these fractions of a percent "should be taken into account in genetic counseling and forensic examination."

The everyday life of a person with unique blood does not differ from its other classifications, with the exception of several factors:
· transfusion is a serious problem, only the same blood can be used for these purposes, while it is a universal donor and suitable for everyone;
Impossibility to establish paternity, if it happened that it is necessary to make DNA, it will not give results, since the child does not have the antigens that his parents have.

Interesting fact! In the USA, Massachusetts, there lives a family where two children have the Bombay phenomenon, only at the same time they also have the A-H type, such blood was diagnosed once in the Czech Republic in 1961. They cannot be donors for each other, since they have a different Rh- factor, and the transfusion of any other group, of course, is impossible. The eldest child has reached the age of majority and became a donor for himself in case of emergency, such a fate awaits his younger sister when she turns 18

And something else interesting on medical topics: here I told in detail and here. Or maybe someone is interested or, for example, well-known

As you know, there are four main blood types in humans. The first, second and third are quite common, the fourth is not so widespread. This classification is based on the content in the blood of the so-called agglutinogens - antigens responsible for the formation of antibodies. The second blood type contains antigen A, the third contains antigen B, the fourth contains both of these antigens, and the first has no antigens A and B, but there is a “primary” antigen H, which, among other things, serves as a “building material” for the production of antigens contained in the second, third and fourth blood groups.

The blood type is most often determined by heredity, for example, if the parents have the second and third groups, the child can have any of the four, in the case when the father and mother have the first group, their children will also have the first, and if, say, the parents have the fourth and the first, the child will have either a second or a third. However, in some cases, children are born with a blood type that, according to the rules of inheritance, they cannot have - this phenomenon is called the Bombay phenomenon, or Bombay blood.

By the way, the Japanese often at the first meeting with a person ask what his blood type is. This is somewhat surprising to foreigners, but the Japanese ask such a question for a reason, but because they want to determine the main character traits of this person.

Let's deal with blood types and check the character by this parameter

In truth, there are no special statistics or scientific grounds to consider such a definition of character as reliable. However, since it is often talked about on TV and many books are sold, in Japan, Korea and Vietnam, the number of people interested in it is increasing.

In the Japanese "horoscope" for the owner of each blood group - A, B, O and AB, there is a character description.
Now this phenomenon has gained extraordinary popularity, releasing books and websites on this topic can make a good business.

A (II) Honest, able to work in a group, very diligent, hide their thoughts and feelings; worry about what others think of them, think clearly, don't like to lose, worry about little things, rely on facts, not emotions; patient, prone to pessimism;

B (III) Active, self-centered, completely immersed in work, hobby, favorite thing; not interested in glory and power, have a heightened sense of justice, are emotional, have a good sense of humor, their mood often changes, they do not pay attention to the rules, they do not pay attention to other people;

O (I) Cheerful, loved by people, romantics, often complain, they are easily touched, stubborn, often help people, if something unpleasant happens, the mood quickly deteriorates; do not hide their feelings, love people with a character different from theirs; optimistic;

AB (IV) Serious, delicate, inquisitive, difficult to express one's feelings, pure, manic, have a heightened sense of justice, mysterious, often doubt people, take promises seriously, have a very complex character.

*************************************************

Within the ABO/Rhesus blood group systems that are used to classify most blood types, there are several rare blood types. The rarest is AB-, this type of blood is observed in less than one percent of the world's population. Types B- and O- are also very rare, each accounting for less than 5% of the world's population. However, in addition to these two main ones, there are more than 30 generally accepted blood typing systems, including many rare types, some of which are observed in a very small group of people.

Blood type is determined by the presence of certain antigens in the blood. The A and B antigens are very common, which makes it easier to classify people based on which antigen they have, whereas people with blood type O have neither. A positive or negative sign after the group means the presence or absence of the Rh factor. At the same time, in addition to antigens A and B, other antigens are also possible, and these antigens can react with the blood of certain donors. For example, someone may have an A+ blood type and not have another antigen in their blood, indicating that they are likely to have an adverse reaction with an A+ blood donation that contains that antigen.

There are no A and B antigens in Bombay blood, so it is often confused with the first group, but there is no H antigen in it either, which can be a problem, for example, when determining paternity - after all, the child does not have a single antigen in the blood that him from his parents.

A rare blood group does not give its owner any problems, except for one thing - if he suddenly needs a blood transfusion, then you can only use the same Bombay blood type, and this blood can be transfused to a person with any group without any consequences.

The first information about this phenomenon appeared in 1952, when the Indian doctor Vhend, conducting blood tests in the family of patients, received an unexpected result: the father had 1 blood type, the mother had II, and the son had III. He described this case in the largest medical journal, The Lancet. Subsequently, some doctors encountered similar cases, but could not explain them. And only at the end of the 20th century the answer was found: it turned out that in such cases, the body of one of the parents mimics (fakes) one blood group, while in fact it has another, two genes are involved in the formation of the blood group: one determines the group blood, the second encodes the production of an enzyme that allows this group to be realized. For most people, this scheme works, but in rare cases, the second gene is missing, and therefore there is no enzyme. Then the following picture is observed: a person has, for example. III blood group, but it cannot be realized, and the analysis reveals II. Such a parent passes on his genes to a child - hence the “inexplicable” blood type appears in the child. There are few carriers of such mimicry - less than 1% of the world's population.

The Bombay phenomenon was discovered in India, where, according to statistics, 0.01% of the population have "special" blood, in Europe Bombay blood is even rarer - about 0.0001% of the inhabitants.

And now a little more detail:

There are three types of genes responsible for the blood group - A, B, and 0 (three alleles).

Each person has two blood type genes - one from the mother (A, B, or 0) and one from the father (A, B, or 0).

6 combinations are possible:

How it works (in terms of cell biochemistry)

On the surface of our red blood cells there are carbohydrates - “H antigens”, they are also “0 antigens”. (On the surface of red blood cells there are glycoproteins that have antigenic properties. They are called agglutinogens.)

Gene A encodes an enzyme that converts part of the H antigens into A antigens. (Gene A encodes a specific glycosyltransferase that attaches the N-acetyl-D-galactosamine residue to agglutinogen, resulting in agglutinogen A).

Gene B encodes an enzyme that converts some of the H antigens into B antigens. (Gene B encodes a specific glycosyltransferase that attaches a D-galactose residue to agglutinogen, resulting in agglutinogen B).

Gene 0 does not code for any enzyme.

Depending on the genotype, carbohydrate vegetation on the surface of erythrocytes will look like this:

For example, we cross parents with groups 1 and 4 and see why they cannot have a child with group 1.

(Because a child with type 1 (00) should receive a 0 from each parent, but a parent with type 4 (AB) does not have a 0.)

Bombay Phenomenon

Occurs when a person does not form the “initial” H antigen on erythrocytes. In this case, the person will not have either A antigens or B antigens, even if the necessary enzymes are present. Well, great and mighty enzymes will come to turn H into A ... oops! but there is nothing to transform, asha no!

The original H antigen is encoded by a gene, which is not surprisingly designated H.
H - gene encoding antigen H
h - recessive gene, antigen H is not formed

Example: a person with the AA genotype must have 2 blood groups. But if he is AAhh, then his blood type will be the first, because there is nothing to make antigen A from.

This mutation was first discovered in Bombay, hence the name. In India, it occurs in one person in 10,000, in Taiwan - in one in 8,000. In Europe, hh is very rare - in one person in two hundred thousand (0.0005%).

An example of how Bombay Phenomenon #1 works: if one parent has the first blood type and the other has the second, then the child cannot have the fourth group, because neither parent has the B gene necessary for the 4th group.

And now the Bombay phenomenon:

The trick is that the first parent, despite their BB genes, does not have B antigens, because there is nothing to make them from. Therefore, despite the genetic third group, from the point of view of blood transfusion, he has the first group.

An example of the Bombay Phenomenon at work #2. If both parents have group 4, then they cannot have a child of group 1.

And now the Bombay Phenomenon

As you can see, with the Bombay phenomenon, parents with group 4 can still get a child with the first group.

Cis position A and B

In a person with type 4 blood, an error (chromosomal mutation) can occur during crossing over, when both genes A and B are on one chromosome, and nothing is on the other chromosome. Accordingly, the gametes of such an AB will turn out to be strange: in one there will be AB, and in the other - nothing.

Of course, chromosomes containing AB, and chromosomes containing nothing at all, will be culled by natural selection, because they will hardly conjugate to normal, wild-type chromosomes. In addition, in children of AAV and ABB, a gene imbalance (violation of viability, death of the embryo) can be observed. The probability of encountering a cis-AB mutation is estimated to be approximately 0.001% (0.012% of cis-AB relative to all ABs).

An example of cis-AB. If one parent has the 4th group, and the other the first, then they cannot have children of either the 1st or the 4th group.

And now the mutation:

The probability of having children shaded in gray is, of course, less - 0.001%, as agreed, and the remaining 99.999% fall on groups 2 and 3. But still, these fractions of a percent "should be taken into account in genetic counseling and forensic examination."

In medicine, four blood groups are described in detail. All of them differ in the location of agglutinins on the surface of erythrocytes. This property is encoded genetically with the help of proteins A, B and H. Bombay syndrome is very rarely recorded in humans. This anomaly is characterized by the presence of the fifth blood group. In patients with the phenomenon, there are no proteins that are determined in the norm. The feature is formed at the stage of intrauterine development, that is, it has a genetic nature. This characteristic of the main fluid of the body is rare and does not exceed one case in ten million.

5 blood type or the history of the Bombay phenomenon

This feature was discovered and described not so long ago, in 1952. The first cases of the absence of antigens A, B and H in humans were registered in India. It is here that the percentage of the population with an anomaly is the highest and is 1 case in 7600. The discovery of Bombay syndrome, that is, a rare blood type, occurred as a result of studying fluid samples using mass spectrometry. Analyzes were made because of the epidemic in the country of such a disease as malaria. The name of the defect was in honor of the Indian city.

Bombay blood theories

Presumably, the anomaly was formed against the background of frequent related marriages. They are common in India due to social customs. Incest not only led to an increase in the prevalence of genetic diseases, but to the emergence of the Bombay syndrome. This feature is currently found in only 0.0001% of the world's population. A rare characteristic of the main fluid in the human body may remain unrecognized due to the imperfection of modern diagnostic methods.

Development mechanism

In total, four blood groups are described in detail in medicine. This division is based on the location of agglutinins on the surface of erythrocytes. Outwardly, these characteristics do not appear in any way. However, they need to be known in order to carry out a blood transfusion from one person to another. If the groups do not match, reactions can occur that can lead to the death of the patient.

This phenomenon is completely determined by the chromosome set of parents, that is, it has a hereditary character. The laying occurs at the stage of intrauterine development. For example, if the father has the first blood type, and the mother has the fourth, then the child will have a second or third. This characteristic is due to combinations of antigens A, B and H. Bombay syndrome occurs against the background of recessive epistasis - a non-allelic interaction. This is what causes the absence of blood proteins.

Features of life and problems with paternity

The presence of this anomaly does not affect human health in any way. A child or adult may not be aware of the presence of a unique feature of the body. Difficulties arise only if the patient needs a blood transfusion. Such people are universal donors. This means that their liquid will suit everyone. However, when defining Bombay syndrome, the patient will need the same unique group. Otherwise, the patient will face incompatibility, which will mean a threat to life and health.

Another problem is the confirmation of paternity. The procedure in people with this blood type is difficult. The determination of family ties is based on the detection of relevant proteins that are not detected when the patient has Bombay syndrome. Therefore, in doubtful situations, more difficult genetic tests will be required.

In modern medicine, no pathologies associated with a rare blood group have been described. Perhaps this feature is caused by the low prevalence of Bombay syndrome. It is assumed that many patients with the phenomenon are unaware of its presence. However, a case of revealing a rare hemolytic disease in a newborn baby whose mother had the fifth blood group is described. The diagnosis was confirmed on the basis of the results of the screening of antibodies, the study of lectins and the determination of the location of agglutinins on the surface of the erythrocytes of the mother and child.

Pathology diagnosed in a patient is accompanied by life-threatening processes. These features are associated with the incompatibility of the blood of the parent and fetus. At the same time, two patients suffer from the disease at once. In the described case, the mother's hematocrit was only 11%, which did not allow her to become a donor for the child.

A big problem in such cases is the lack of this rare type of physiological fluid in blood banks. This is primarily due to the low prevalence of Bombay syndrome. The difficulty is also the fact that patients may not be aware of the feature. At the same time, according to the available data, many people with the fifth group willingly agree to be donors, since they realize the importance of creating a blood bank. In case of hemolytic disease of the newborn against the background of diagnosis in the mother of the Bombay syndrome, the cases of which are rare, there is also the possibility of conservative treatment without the use of blood transfusion. The effectiveness of such therapy depends on the severity of pathological changes in the body of the mother and child.

The Importance of Unique Blood

The anomaly is considered poorly understood. Therefore, it is too early to talk about the impact of the feature on the health of the planet's population and medicine. It is indisputable that the occurrence of the Bombay syndrome complicates the already difficult procedure of blood transfusion. The presence of a 5th blood group in a person endangers life and health when a transfusion becomes necessary. At the same time, a number of scientists are inclined to believe that such an evolutionary event may have a beneficial effect in the future, since such a structure of the biological fluid is considered perfect in comparison with other common options.

We know from school that there are four main blood groups. The first three are common, while the fourth is rare. Classification of groups occurs according to the content of agglutinogens in the blood, which form antibodies. However, few people know that there is a fifth group, called the "Bombay Phenomenon".

To understand what is at stake, you should remember the content of antigens in the blood. So, the second group contains antigen A, the third - B, the fourth contains antigens A and B, and in the first group these elements are absent, but it contains antigen H - this is a substance that takes part in the construction of other antigens. In the fifth group there is neither A, nor B, nor H.

Inheritance

Blood type determines heredity. If the parents have the third and second groups, then their children can be born with any of the four groups, if the parents have the first group, then the children will have only the blood of the first group. However, there are times when parents give birth to children with an unusual, fifth group or Bombay phenomenon. There are no A and B antigens in this blood, which is why it is often confused with the first group. But in Bombay blood there is no H antigen contained in the first group. If a child has a Bombay phenomenon, then it will not be possible to accurately determine paternity, since there is not a single antigen in the blood that his parents have.

Discovery history

The discovery of an unusual blood group was made in 1952, in India, in the Bombay region. During malaria, mass blood tests were carried out. During the examinations, several people were identified whose blood does not belong to any of the four known groups, since it did not contain antigens. These cases have come to be known as the "Bombay Phenomenon". Later, information about such blood began to appear around the world, and in the world for every 250,000 people, one has a fifth group. In India, this figure is higher - one per 7,600 people.

According to scientists, the emergence of a new group in India is due to the fact that closely related marriages are allowed in this country. According to the laws of India, the continuation of the family within the caste allows you to save a position in society and family wealth.

What's next

After the discovery of the Bombay phenomenon, scientists at the University of Vermont made a statement that there were other rare blood types. The latest discoveries were named Langereis and Junior. These species contain previously completely unknown proteins that are responsible for the blood type.

The uniqueness of the 5th group

The most common and oldest is the first group. It originated in the time of the Neanderthals - it is more than 40 thousand years old. Almost half of the world's population has the first blood group.

The second group appeared about 15 thousand years ago. It is also not considered rare, but according to various sources, about 35% of people are its carriers. Most often, the second group is found in Japan, Western Europe.

The third group is less common. Its carriers are about 15% of the population. Most people with this group are found in Eastern Europe.

Until recently, the fourth group was considered the newest. About five thousand years have passed since its appearance. It occurs in 5% of the world's population.

The Bombay Phenomenon (blood type V) is considered the newest, having been discovered decades ago. There are only 0.001% of people on the entire planet with such a group.

The formation of the phenomenon

The classification of blood groups is based on the content of antigens. This information is used in blood transfusion. It is believed that the antigen H contained in the first group is the "progenitor" of all existing groups, since it is a kind of building material from which antigens A and B appeared.

The laying of the chemical composition of the blood occurs even in utero and depends on the blood groups of the parents. And here, geneticists can say with what possible groups a baby can be born with simple calculations. Sometimes, nevertheless, deviations from the usual norm occur, and then children are born who show recessive epistasis (the Bombay phenomenon). There are no antigens A, B, H in their blood. This is the uniqueness of the fifth blood group.

People with the fifth group

These people live like millions of others, with other groups. Although they have some difficulties:

1. It is difficult to find a donor. If it is necessary to make a blood transfusion, only the fifth group can be used. However, Bombay blood can be used for all groups without exception, and there are no consequences.
2. Paternity cannot be established. If you need to do a DNA test for paternity, then it will not give any results, since the child will not have the antigens that his parents have.

In the USA there is a family in which two children were born with the Bombay phenomenon, and even with the A-H type. Such blood was detected once in the Czech Republic in 1961. There are no donors for children in the world, and transfusion of other groups is fatal for them. Because of this feature, the eldest child became a donor for himself, and his sister is waiting for the same.

Biochemistry

It is generally accepted that there are three types of genes responsible for blood types: A, B and 0. Each person has two genes - one receives from the mother, and the second from the father. Based on this, there are six gene variations that determine the blood type:

1. The first group is characterized by the presence of 00 genes.
2. For the second group - AA and A0.
3. The third contains antigens 0B and BB.
4. In the fourth - AB.

Carbohydrates are located on the surface of erythrocytes, they are also antigens 0 or antigens H. Under the influence of certain enzymes, the coding of the antigen H into A occurs. The same thing happens when the coding of the antigen H into B. Gene 0 does not produce any coding for the enzyme. When there is no synthesis of agglutinogens on the surface of erythrocytes, i.e., there is no initial H antigen on the surface, then this blood is considered Bombay. Its peculiarity is that in the absence of the H antigen, or "source code", there is nothing to turn into other antigens. In other cases, various antigens are found on the surface of erythrocytes: the first group is characterized by the absence of antigens, but the presence of H, for the second - A, for the third - B, for the fourth - AB. People with the fifth group do not have any genes on the surface of erythrocytes, and they don’t even have H, which is responsible for coding, even if there are enzymes that are encoded, it is impossible to turn H into another gene, because this source H does not exist.

The original H antigen is encoded by a gene called H. It looks like this: H is the gene that encodes the H antigen, h is the recessive gene in which the H antigen is not formed. As a result, when conducting a genetic analysis of the possible inheritance of blood groups in parents, children with a different group may be born. For example, parents with the fourth group cannot have children with the first group, but if one of the parents has a Bombay phenomenon, then they can have children with any group, even with the first.

Conclusion

Over the course of many millions of years, evolution takes place, and not only of our planet. All living beings change. Evolution did not leave blood either. This liquid not only allows us to live, but also protects against the negative effects of the environment, viruses and infections, neutralizing them and preventing them from penetrating into vital systems and organs. Similar discoveries made decades ago by scientists in the form of the Bombay phenomenon, as well as other types of blood types, remain a mystery. And it is not known how many secrets not yet revealed by scientists are kept in the blood of people around the world. Maybe after a while it will become known about another phenomenal discovery of a new group that will be very new, unique, and people with it will have incredible abilities.

The human body is famous for its uniqueness. Due to the various mutations that occur daily in our body, we become individual, since some of the signs that we acquire differ significantly from the same external and internal factors of other people. This also applies to blood groups.

It is generally accepted to subdivide it into 4 types. However, it is extremely rare, but it occurs that a person who should have one (due to the genetic characteristics of the parents) has a completely different, specific one. This paradox is known as the Bombay Phenomenon.

What it is?

This term is understood as a hereditary mutation. It is extremely rare - up to 1 case per ten million people. The Bombay phenomenon takes its name from the Indian city of Bombay.

In India, there is one settlement, in whose people the “chimeric” blood type is quite common. This means that when determining erythrocyte antigens by standard methods, the result shows, for example, the second group, although in fact, due to a mutation in a person, the first.

This is due to the formation of a recessive pair of H genes in a person. Normally, if a person is heterozygous for this gene, then the trait does not appear, the recessive allele cannot perform its function. Due to the incorrect combination of parental chromosomes, a recessive pair of genes is formed, and the Bombay phenomenon takes place.

How does it develop?

The history of the phenomenon

A similar phenomenon was described in many medical publications, but almost until the middle of the 20th century, no one had any idea why this was happening.

This paradox was discovered in India in 1952. The doctor, conducting a study, noticed that the parents had the same blood types (the father had the first, and the mother had the second), and the born child had the third.

Having become interested in this phenomenon, the doctor was able to determine that the father's body had somehow managed to change, which made it possible to assume that he had the first group. The modification itself occurred due to the lack of an enzyme that allows the synthesis of the desired protein, which would help determine the necessary antigen. However, if there was no enzyme, then the group could not be determined correctly.

The phenomenon among representatives is quite rare. Somewhat more often you can find carriers of "Bombay blood" in India.

Bombay blood theories

One of the main theories for the emergence of a unique blood type is a chromosomal mutation. For example, in a person with possible recombination of alleles on the chromosomes. That is, during the formation of gametes, the genes responsible for can move as follows: genes A and B will be in the same gamete (a subsequent individual can receive any group except the first), and the other gamete will not carry the genes responsible for the blood group. In this case, the inheritance of the gamete without antigens is possible.

The only obstacle to its spread is that many of these gametes die without even entering embryogenesis. However, it is possible that some survive, which subsequently contributes to the formation of Bombay blood.

It is also possible to disrupt the gene distribution at the stage of the zygote or embryo (as a result of maternal malnutrition or excessive alcohol consumption).

The mechanism of development of this condition

As said, it all depends on the genes.

A person's genotype (the totality of all his genes) directly depends on the parent, more precisely, on what signs have passed from parents to children.

If you study the composition of antigens more deeply, you will notice that the blood type is inherited from both parents. For example, if one of them has the first, and the other has the second, then the child will have only one of these groups. If the Bombay phenomenon develops, things happen a little differently:

• The second blood type is controlled by the a gene, which is responsible for the synthesis of a special antigen - A. The first, or zero, has no specific genes.
• The synthesis of antigen A is due to the action of the region of the H chromosome responsible for differentiation.
• If there is a failure in the system of this DNA segment, then the antigens cannot be differentiated correctly, because of which the child can acquire antigen A from the parent, and the second allele in the genotypic pair cannot be determined (conditionally it is called nn). This recessive pair suppresses the action of site A, as a result of which the child has the first group.

To summarize, it turns out that the main process that causes the Bombay phenomenon is recessive epistasis.

Non-allelic interaction

As mentioned, the development of the Bombay phenomenon is based on a non-allelic interaction of genes - epistasis. This type of inheritance differs in that one gene suppresses the action of another, even if the suppressed allele is dominant.

The genetic basis for the development of the Bombay phenomenon is epistasis. The peculiarity of this type of inheritance is that the recessive epistatic gene is stronger than the hypostatic one, but which determines the blood type. Therefore, the inhibitor gene causing suppression is incapable of producing any trait. Because of this, a child is born with “no” blood type.

Such an interaction is genetically determined, so it is possible to identify the presence of a recessive allele in one of the parents. It is impossible to influence the development of such a blood group, and even more so to change it. Therefore, for those who have the Bombay phenomenon, the scheme of everyday life dictates some rules, following which, such people will be able to live normally and not be afraid for their health.

Features of the life of people with this mutation

In general, people who carry Bombay blood are no different from ordinary people. However, problems arise when a transfusion is required (major surgery, accident or disease of the blood system). Due to the peculiarity of the antigenic composition of these people, they cannot be transfused with blood other than Bombay. Especially often such errors occur in extreme situations, when there is no time to thoroughly study the analysis of the patient's erythrocytes.

The test will show, for example, the second group. When a patient is transfused with blood of this group, intravascular hemolysis may develop, which will lead to death. It is because of this incompatibility of antigens that the patient needs only Bombay blood, always with the same Rh as his.

Such people are forced to conserve their own blood from the age of 18, so that later they have something to transfuse if necessary. There are no other features in the body of these people. Thus, it can be said that the Bombay phenomenon is a “way of life” and not a disease. You can live with it, you just need to remember your “uniqueness”.

Paternity issues

The Bombay phenomenon is the “marriage storm”. The main problem is that when determining paternity without conducting special studies, it is impossible to prove the existence of the phenomenon.

If suddenly someone decided to clarify the relationship, then be sure to inform him that the presence of such a mutation is possible. The test for genetic matching in such a case should be carried out more extensively, with the study of the antigenic composition of blood and red blood cells. Otherwise, the child's mother runs the risk of being left alone, without a husband.

This phenomenon can only be proved with the help of genetic tests and determination of the type of inheritance of the blood group. The study is quite expensive and not currently widely used. Therefore, at the birth of a child with a different blood type, the Bombay phenomenon should be immediately suspected. The task is not easy, as only a few dozen people know about it.

Bombay blood and its current occurrence

As has been said, people with Bombay blood are rare. In representatives of the Caucasian race, this type of blood practically does not occur; among Indians, this blood is more common (on average, in Europeans, the occurrence of this blood is one case per 10 million people). There is a theory that this phenomenon develops due to the national and religious characteristics of the Hindus.

Everyone knows that it is a sacred animal and its meat should not be eaten. Perhaps due to the fact that beef contains some antigens that can cause a change, Bombay blood shows up more often. Many Europeans eat beef meat, which serves as a prerequisite for the emergence of the theory of antigenic suppression of the recessive epistatic gene.

It is possible that climatic conditions also influence, but this theory is not currently being studied, so there is no evidence to substantiate it.

The Significance of Bombay Blood

Unfortunately, few people have heard of Bombay blood at the present time. This phenomenon is known only to hematologists and scientists working in the field of genetic engineering. Only they know about the Bombay phenomenon, what it is, how it manifests itself and what needs to be done when it is detected. However, the exact cause of this phenomenon has not yet been identified.

From an evolutionary point of view, Bombay blood is an unfavorable factor. Many people sometimes need a transfusion or replacement to survive. In the presence of Bombay blood, the difficulty lies in the impossibility of replacing it with another type of blood. Because of this, fatal outcomes often develop in such people.

Looking at the problem from the other side, it is possible that Bombay blood is more perfect than blood with a standard antigenic composition. Its properties have not been fully studied, so it cannot be said what the Bombay phenomenon is - a curse or a gift.

In medicine, four blood groups are described in detail. All of them differ in the location of agglutinins on the surface of erythrocytes. This property is encoded genetically with the help of proteins A, B and H. Bombay syndrome is very rarely recorded in humans. This anomaly is characterized by the presence of the fifth blood group. In patients with the phenomenon, there are no proteins that are determined in the norm. The feature is formed at the stage of intrauterine development, that is, it has a genetic nature. This characteristic of the main fluid of the body is rare and does not exceed one case in ten million.

5 blood type or the history of the Bombay phenomenon

This feature was discovered and described not so long ago, in 1952. The first cases of the absence of antigens A, B and H in humans were registered in India. It is here that the percentage of the population with an anomaly is the highest and is 1 case in 7600. The discovery of Bombay syndrome, that is, a rare blood type, occurred as a result of studying fluid samples using mass spectrometry. Analyzes were made because of the epidemic in the country of such a disease as malaria. The name of the defect was in honor of the Indian city.

Bombay blood theories

Presumably, the anomaly was formed against the background of frequent related marriages. They are common in India due to social customs. Incest not only led to an increase in the prevalence of genetic diseases, but to the emergence of the Bombay syndrome. This feature is currently found in only 0.0001% of the world's population. A rare characteristic of the main fluid in the human body may remain unrecognized due to the imperfection of modern diagnostic methods.

Development mechanism

In total, four blood groups are described in detail in medicine. This division is based on the location of agglutinins on the surface of erythrocytes. Outwardly, these characteristics do not appear in any way. However, they need to be known in order to carry out a blood transfusion from one person to another. If the groups do not match, reactions can occur that can lead to the death of the patient.

This phenomenon is completely determined by the chromosome set of parents, that is, it has a hereditary character. The laying occurs at the stage of intrauterine development. For example, if the father has the first blood type, and the mother has the fourth, then the child will have a second or third. This characteristic is due to combinations of antigens A, B and H. Bombay syndrome occurs against the background of recessive epistasis - a non-allelic interaction. This is what causes the absence of blood proteins.

Features of life and problems with paternity

The presence of this anomaly does not affect human health in any way. A child or adult may not be aware of the presence of a unique feature of the body. Difficulties arise only if the patient needs a blood transfusion. Such people are universal donors. This means that their liquid will suit everyone. However, when defining Bombay syndrome, the patient will need the same unique group. Otherwise, the patient will face incompatibility, which will mean a threat to life and health.

Another problem is the confirmation of paternity. The procedure in people with this blood type is difficult. The determination of family ties is based on the detection of relevant proteins that are not detected when the patient has Bombay syndrome. Therefore, in doubtful situations, more difficult genetic tests will be required.

In modern medicine, no pathologies associated with a rare blood group have been described. Perhaps this feature is caused by the low prevalence of Bombay syndrome. It is assumed that many patients with the phenomenon are unaware of its presence. However, a case of revealing a rare hemolytic disease in a newborn baby whose mother had the fifth blood group is described. The diagnosis was confirmed on the basis of the results of the screening of antibodies, the study of lectins and the determination of the location of agglutinins on the surface of the erythrocytes of the mother and child.

Pathology diagnosed in a patient is accompanied by life-threatening processes. These features are associated with the incompatibility of the blood of the parent and fetus. At the same time, two patients suffer from the disease at once. In the described case, the mother's hematocrit was only 11%, which did not allow her to become a donor for the child.

A big problem in such cases is the lack of this rare type of physiological fluid in blood banks. This is primarily due to the low prevalence of Bombay syndrome. The difficulty is also the fact that patients may not be aware of the feature. At the same time, according to the available data, many people with the fifth group willingly agree to be donors, since they realize the importance of creating a blood bank. In case of hemolytic disease of the newborn against the background of diagnosis in the mother of the Bombay syndrome, the cases of which are rare, there is also the possibility of conservative treatment without the use of blood transfusion. The effectiveness of such therapy depends on the severity of pathological changes in the body of the mother and child.

The Importance of Unique Blood

The anomaly is considered poorly understood. Therefore, it is too early to talk about the impact of the feature on the health of the planet's population and medicine. It is indisputable that the occurrence of the Bombay syndrome complicates the already difficult procedure of blood transfusion. The presence of a 5th blood group in a person endangers life and health when a transfusion becomes necessary. At the same time, a number of scientists are inclined to believe that such an evolutionary event may have a beneficial effect in the future, since such a structure of the biological fluid is considered perfect in comparison with other common options.