Due to its uniqueness, the rare blood type "Bombay blood group" is always in the headlines for its need.
It was first discovered in Mumbai (then Bombay) in 1952 by Dr. Y. M Bhende. This blood phenotype is prevalent in India, Bangladesh, Pakistan, and areas of the Middle East. It is a relatively rare blood group that is found in about 0.0004 percent of the human population (around 4 million people). In Mumbai, the prevalence is as high as 0.01 percent, which indicates that one in every 10,000 people has this blood group.
The blood group of a person depends on type of antigen present on red blood cells. ABO and Rh system of blood groups are most common. Each RBC consists of an antigen on the surface which can determine to which blood group a person belongs. The Bombay blood group occurs in those individuals who have inherited two recessive traits of H gene. Phenotype of this blood group lacks A, B and H antigen on RBC but has anti-H serum. A point mutation in the group H gene causes it. The mutant variety, also known as the H gene, does not code for any protein.
A series of enzymes (glycosyltransferases) that transfer monosaccharides are involved in the production of the H antigen, as well as the A and B antigens. The antigens that result are oligosaccharide chains that are linked to lipids and proteins in the RBC membrane. A particular fructosyltransferase produces the H antigen. The H antigen is transformed into either the A antigen, the B antigen, or both antigens, depending on a person's ABO blood type. The H antigen is unaltered in people with blood group O. As a result, the H antigen is found in the highest concentrations in blood type O and the lowest concentrations in blood type AB. The H locus (FUT1) and the Se locus (FUT2) are two areas of the genome that encode enzymes with remarkably similar substrate specificities (FUT2). The FUT1 gene, which is expressed in RBCs, is found in the H locus. For the H antigen to be generated on RBCs, at least one functional copy of FUT1 (H/H or H/h) must be present. The Bombay phenotype occurs when both copies of FUT1 are inactive (h/h). The FUT2 gene, which is expressed in secretory glands, is found in the Se locus. Secretors (Se/Se or Se/se) have at least one copy of a functional enzyme in their bodies. They make a soluble H antigen that can be discovered in saliva and other body fluids. No soluble H antigen is produced by "non-secretors" (se/se). FUT2 encodes an enzyme that is involved in the manufacture of Lewis blood type antigens.
It's largely due to intensive breeding within the same lineage or within a small population. Marriages that are frequently consanguineous causes the blood type or gene pool to be severely hampered. As a result, the Bombay blood group is believed to share a common ancestor. The H antigen, which is present in O, is not expressed in people with this unusual trait. As a result, no matter what alleles of the A and B blood type genes they have, they cannot create A or B antigen on their RBC since A and B antigen are made from H antigen. As a result, people with the bombay blood type can donate blood to any member of the ABO blood group system, but they can only receive blood from people with the bombay blood phenotype. Patients with anti-H circulation who receive blood transfusions containing H antigen may experience a hemolytic response.
Hence its important to understand that “There are many reel heroes in Bombay, but if your blood type is H, you can become a real-life hero by donating blood”.
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