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 are significantly different from the same external and internal factors of other people. This also applies to blood types.
It is usually customary to subdivide it into 4 types. However, it is extremely rare, but it is found that a person who must have one blood group (due to the genetic characteristics of the parents) has a completely different, specific one. A similar paradox is called the “Bombay phenomenon”.
What it is?
By this term is understood a hereditary mutation. It is extremely rare - up to 1 case per ten million people. The Bombay phenomenon got 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 the mutation in humans, the first.
This is due to the formation in a person of a recessive pair of N. genes. Normally, if a person is heterozygous for this gene, then the symptom does not appear, the recessive allele cannot fulfill its function. Due to the incorrect association of the parent chromosomes, the formation of a recessive pair of genes occurs, and the Bombay phenomenon takes place.
How does its development take place?
History of the phenomenon
A similar phenomenon has been described in many medical journals, 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, noted that the parents had the same blood types (the father had the first and the mother had the second), and the child had a third.
Having become interested in this phenomenon, the doctor was able to determine that the father’s body was able to somehow 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 us to synthesize the desired protein, which would help determine the necessary antigen. However, since there was no enzyme, then the group could not be determined correctly.
The phenomenon of the Caucasian race is quite rare. More often you can find carriers of "bombing blood" in India.
Theories of Bombay Blood
One of the main theories for the appearance of a unique blood group is a chromosomal mutation. For example, in a person with a fourth blood group, recombination of alleles on chromosomes is possible. That is, with the formation of gametes, the genes responsible for the inheritance of a blood group can move as follows: genes A and B will be in the same gamete (the next individual can get any group except the first), and the other gamete will not carry the genes responsible for the blood group . In this case, the gamete can be inherited without antigens.
The only obstacle to its spread is the fact that many such gametes die without even entering embryogenesis. However, some may survive, which subsequently contributes to the formation of Bombay blood.
A violation of the gene distribution at the zygote or embryo stage is also possible (as a result of a maternal nutritional disorder or excessive alcohol consumption).
The mechanism of development of this condition
As said, it all depends on the genes.
The human genotype (the totality of all its genes) directly depends on the parent, more precisely, on what signs have passed from parents to children.
If we study the composition of antigens more deeply, we can see that the blood group 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, everything happens a little differently:
- The second blood group is controlled by gene a, which is responsible for the synthesis of a special antigen - A. The first, or zero, does not have specific genes.
- The synthesis of antigen A is due to the action of the region of chromosome H, which is responsible for differentiation.
- If a malfunction occurs in the system of this DNA region, then the antigens cannot differentiate correctly, because of which the child can acquire antigen A from the parent, and the second allele in the genotypic pair cannot be determined (it is conventionally called nn). This recessive pair suppresses the action of section A, as a result of which the child has the first group.
If we generalize everything, it turns out that the main process that causes the Bombay phenomenon is recessive epistasis.
Non-allelic interaction
As was said, the basis of the development of the Bombay phenomenon is non-allelic interaction of genes - epistasis. This type of inheritance is characterized in that one gene inhibits the action of another, even if the suppressed allele is dominant.
The genetic basis for the development of the Bombay phenomenon - epistasis. The peculiarity of this type of inheritance is that the recessive epistatic gene is stronger than the hypostatic gene, but which determines the blood group. Therefore, the inhibitory gene that causes suppression is not capable of the formation of any trait. Because of this, a child is born with a “no” blood type.
Such an interaction is genetically determined; therefore, it is possible to detect 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 a Bombay phenomenon, the daily routine dictates certain rules, observing that such people can live normally and not be afraid for their health.
Features of the life of people with this mutation
In general, people carrying Bombay blood are no different from ordinary people. However, problems appear when a transfusion is required (a major operation, an accident, or a blood system disease). Due to the peculiarity of the antigenic composition of these people, they should not 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 red blood cells.
The test will show, for example, the second group. When a patient is transfused with blood of this group, intravascular hemolysis can develop, which will lead to death. It is because of such incompatibility of antigens that the patient needs only bombing blood, always with the same rhesus as he has.
Such people are forced to conserve their own blood from the age of 18, so that later there is something to transfuse if necessary. There are no other features in the body of these people. Thus, we can say that the Bombay phenomenon is a “way of life” and not a disease. You can live with him, only you should remember about your “uniqueness”.
Paternity issues
The Bombay phenomenon is a “thunderstorm of marriage”. The main problem is that in determining paternity without special studies it is impossible to prove the presence of a phenomenon.
If suddenly someone decided to clarify the relationship, then you should definitely inform him that a similar mutation is possible. A test for genetic coincidence 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 mother of the child runs the risk of being left alone, without a husband.
This phenomenon can only be proved using genetic tests and determining the type of inheritance of a blood group. The study is quite expensive and not widely used at present. Therefore, at the birth of a child with a different blood type, the Bombay phenomenon should be immediately suspected. The task is not easy, since dozens of people know about it.
Bombay blood and its current incidence
As was said, people with Bombay blood are not common. In representatives of the Caucasian race, this type of blood practically does not occur; among Hindus, this blood is more common (on average among 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 Indians.
Everyone knows that in India, a cow is a sacred animal and its meat cannot be eaten. Perhaps due to the fact that beef contains some antigens that can cause a change in the genetic code, Bombay blood is more often manifested. Many Europeans eat beef meat, which serves as a prerequisite for the emergence of the theory of antigenic suppression of a recessive epistatic gene.
Climatic conditions may also have an impact, but this theory is not currently being studied, so there is no evidence to justify it.
The significance of Bombay blood
Unfortunately, few have heard about the bombing blood. 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 identified. However, the exact cause of this phenomenon has not yet been identified.
Seen from the point of view of evolution, Bombay blood is an unfavorable factor. Many people sometimes require 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, deaths often develop in such people.
If you look at the problem from the other side, it is possible that Bombay blood is more perfect than blood with standard antigenic composition. Its properties are not fully understood, therefore, it cannot be said what a bombing phenomenon is - a curse or a gift.