HH blood group, also known as Bombay blood group, is a blood group classification based on a rare blood protein. First, Dr. Y. M. It was named by Bhende because it was discovered in Bombay in 1952. The Bombay blood type is found mostly in the Indian sub-continent (India, Bangladesh and Pakistan), but can also be found in some Middle Eastern countries, such as Iran.
Basic Reminders About Blood Groups
Blood groups are the name given to molecules called antigens that are usually located outside of cells. These molecules are known as "self-antigen" or "self-protein" if they are the own antigens of a living being, and "non-self-antigen" if they are antigens belonging to a foreign cell. Antigens that do not belong to the body itself usually trigger the defense system and cause the production of antibodies. These antibodies are specifically produced against antigens, and if a successful immune response occurs, they target and destroy these antigens. In most cases, each antibody binds to only 1 Specific Antigen; but in rare cases, it has also been observed that an antibody binds to more than one antigen (this is called cross-reaction).
Here, the famous ABO blood group system was developed based on antigens called A and B found on the surface of red blood cells. Although the ABO blood type system is very popular, there are actually 38 different blood type systems, even in humans alone. ABO is seen as the most important of these because of its effect, but the Rh factor, which you may be familiar with, is another popular classification method.
H Antigen: What Is The Bombay Phenotype?
Similarly, the HH CAD group is also classified by a single antigen: the H antigen. This antigen is found on almost all red blood cells and is even involved in the production of antigens that make up the ABO blood group. So what is rare and popularly known as the "Bombay blood group" is not those that have the H antigen; they are those that lack the H antigen. If a person does not have H antigen in their blood, the person is known as H/h or Oh or Bombay phenotype. This phenotype; It occurs in Taiwan in 1 out of every 8,000 people, in India in 1 in every 10,000 people, and in Europe in one in every 1 million people.
In fact, the absence of an H antigen does not have any known health harm; however, if blood transfer is required to someone with a Bombay phenotype, these people can only receive blood from individuals with a Bombay phenotype (i.e., not an H antigen). If they receive blood from one of the 0 blood groups without the Bombay phenotype, they may show a very heavy blood transfusion response.
On the other hand, since the H antigen acts as a precursor molecule in the production of ABO blood blood group antigens, Abo antigens cannot also be produced in individuals without the H antigen. In this case, incorrect results can be obtained in tests such as paternity tests - which have been processed in some soap operas in India!
What Can A Soap Opera Teach Us About Blood Types?
For example, in a series called General Hospital, it is unclear who the father of a character named Monica is. Monica's blood type was determined to be A (genotype A0) and her child's blood type was determined to be 0 (genotype 00). Since the child must receive the allele 0 from his father, there are only three blood types that the father can have: A0, B0, or 00. In other words, the father of the child is either group a, group B, or group 0; it cannot be AB. However, Alan, who is Monica's husband, has a blood type of AB, and the only possible other father candidate is Rick, who has a blood type of 0.
But come and see, Dad is Alan! This may be possible because both he and Monica are carriers of the Bombay phenotype (i.e. their genotype H/h). Therefore, they can produce ab0 blood group antigens themselves, but their children cannot produce ab0 blood group antigens because their genotype is h/H by taking the recessive h allele from both parents. For this reason, although they received the allele A or B from Alan, the antigen A or B cannot be produced in the child's red blood cells, and therefore the blood group is thought to be 0.
As can be seen from here, to determine the likelihood that you will have the Bombay phenotype without testing, you can look at whether you carry the following conditions:
- If your own blood type is not 0, and
- If your partner's blood type is also not 0, and
- If your child's blood type is 0, the child is likely to have a Bombay phenotype.
Alike:
- If the blood type of the mother or father is AB, and
- If the child's blood type is 0, the child is likely to have a Bombay phenotype.
Alike:
- If the child's blood type is AB and
- If the mother or father's blood type is 0, the parent with blood type 0 is likely to be the Bombay phenotype.
But this result must be verified by a special test, and all other possibilities must be eliminated in this way. As an ethical warning, there is a risk that this test will reveal that your child is not your own child; if you have such concerns, you should act knowingly.
H Phenotype Biochemistry
Biosynthesis of H antigen and A and B antigens involves a number of enzymes (glycosyltransferases) that transfer monosaccharides. The resulting antigens are oligosaccharide chains that bind to lipids and proteins anchored to the RBC membrane.
The H antigen is produced by a specific fucosyltransferase. Depending on the person's ABO blood group, the H antigen is converted to a antigen, B antigen, or both. If the person's blood type is O, The H antigen remains unchanged. For this reason, the H antigen is present in the highest amount in the O blood group and the lowest amount in the AB blood group.
Two regions of the genome encode two enzymes with very similar substrate specifics: the H locus (FUT1) and the Se locus (FUT2).
The H locus contains the FUT1 gene, which is expressed in RBCs. In order for the H antigen to be produced in red blood cells, at least one functional copy (H/H or H/H) of Fut1 must be present. If both copies of fut1 are inactive (s/h), The Bombay phenotype is formed.
The SE locus contains the FUT2 gene, which is expressed in the secretory glands. Individuals with a" secretor " (Se/Se or Se/se) contain at least one copy of a functioning enzyme. They produce a soluble form of H antigen found in saliva and other bodily fluids. "Non-secretory" (se/se) does not produce soluble H antigen. The enzyme encoded by FUT2 is also involved in the synthesis of antigens of the Lewis blood group.
H Phenotypes
Common Phenotypes
Phenotypes that are secretive and that are not are the most common Bombay phenotypes. We can list their common characteristics as follows:
Common Features Of The Secretive H Phenotype
- H antigen is produced in red blood cells.
- H antigen is produced in saliva.
- Anti-H is not produced.
- Genotypes: H / H or H/ h; Se / Se or Se / se
Common Features Of The Non-Secretive H Phenotype
- H antigen is produced in red blood cells.
- H antigen is not produced in saliva.
- Anti-H is not produced.
- Genotypes: H / H or H / h; se / se
Non-Common Phenotypes
The Bombay phenotype and para-Bombay phenotype are relatively rare. In India, where H deficiency was first discovered, the co-incidence of both phenotypes is 1 in 10,000. H deficiency is slightly more common in Taiwan, affecting 1 in 8,000 people. Relatively large numbers of H-deficient individuals have been found on Reunion Island, a small French island 800 km east of Madagascar in the Indian Ocean. Both the classical Bombay phenotype and a new variant type partial H deficiency have been observed in the Islanders. 1 in a million people in Europe experience H deficiency.
Bombay Phenotype
- H antigen is not produced in red blood cells.
- H antigen is not produced in saliva.
- Anti-H is present in serum.
- Genotype: h / H se / se
Para - Bombay Phenotype
- H antigen is very poorly produced in red blood cells.
- H antigen can be produced in saliva or not.
- Anti-H is present in serum.
- Genotype: (H), Se / Se or Se / se or se / se