Bombay Blood Group

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Dr. J K Jha
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Last Updated on January 14, 2024 by The Health Master

INTRODUCTION – Bombay Blood Group

The Bombay blood group is rare blood group with absence or deficiency of H antigen. Bombay blood phenotype was first discovered in Bombay in India by Dr. Y.M. Bhende in 1952. Named for the town during which it had been first discovered.

It is a blood group which shows absence of A, B, H antigens on red cells and presence of anti-A, anti-B and anti-H antibodies in serum. The H antigen is located on the surface of red blood cells and is the precursor of A and B antigens.

H antigen are often synthesized by H gene FUT1 and FUT2 which is found on chromosome 19 and provides rise to glycosyl transferase that add 1-fucose to a precursor substance to produce H antigen on red cells.

Bombay group would be categorized as O group because they wouldn’t show any reaction to anti-A and anti-B antibodies just like a normal O group.

When a cross matching is completed then it might show cross-reactivity or incompatibility. The reverser or serum grouping has got to be performed to detect the Bombay blood group.

Picture: Pixabay


Karl Landsteiner in his discovery of the famous ABO blood types identified that the red blood cells have an “H” antigen on their cell surfaces. This H antigen is the precursor of A & B antigens.

This H antigen is modified into “A” or “B” antigen like wise and therefore the individual get either “A” ,”B” or “AB” blood type . This modification occurs within the presence of a Transferase Enzyme.

If this enzyme is lacking, then the “H “antigen isn’t modified and these individuals have the “O” blood group.

Detection of Bombay Phenotype

This blood group could also be commonly mistaken as ‘O’ and lots of a time, not identified in the least if proper blood grouping or testing practices aren’t followed. During routine grouping conducted at the hospital’s bank , the blood type may show up as O, with no reaction to Anti-A and Anti-B antibodies.

However, Bombay Phenotype is detected when reverse grouping is performed; it shows agglutination with O cells, proving the rare Bombay ‘Oh’ Phenotype blood. It is important to take care in predicting the ABO blood group of youngsters supported the phenotypes of their parents.

This is thanks to the very fact that a 3rd antigen (H) on the surface of red cells can prevent the expected ABO blood group from occurring.

Repeated testing is then done because it is vital to perform reverse grouping or serum grouping to detect the Bombay blood group.

Individuals with Bombay blood group can donate to all ABO blood group people and can only accept from Bombay blood group people.

The Bombay anti-H is an IgM antibody which will bind complement and cause red cell lysis. Because the H antigen is common to all or any ABO blood type , Bombay blood is incompatible with all ABO donors.


  • 1. Absence of H, A and B antigens; NO agglutination with anti-A, anti-B, or anti-H lectin.
  • 2. Presence of anti-A, anti-B, anti-AB and potent wide thermal range anti-H within the serum.
  • 3. A, B, H non-secretor (no A, B, or H substances present in saliva).
  • 4. Absence of H enzyme in serum and H antigen on red cells.
  • 5. Presence of A or B enzymes in serum and red cells.
  • 6. A recessive mode of inheritance.
  • 7. Red cells of the Bombay group are compatible only with the serum from another Bombay individual.

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