Bombay blood group

Have you heard about the Bombay blood group? It’s one the rarest blood group ( 0.0004%) found mostly in countries like India, Pakistan, Bangladesh and some countries of the Middle East. 


Let’s learn about this interesting blood group : 


  1. Taking help from pizzas 
  2. Biology behind it
  3. Why usual blood test can’t find the Bombay blood group? 
  4. Blood Transfusion
  5. How Bombay blood group got its name? 

Starting from basic definition, Blood groups can be classified on the basis of antigens attached over the red blood cell. 


We are told that if RBC has A antigens attached, it is A blood group;  if B antigens attached, then it is B blood group, and if nothing is attached,  it is O blood group. 


This is wrong. Or partially right. 


Let’s have some pizzas first. 


Yes, pizzas can be a good example to explain blood groups. Let’s start cooking. 


Consider pizza base as a red blood cell, pizza sauce as H – antigen, Bell peppers (Capsicum) as A – antigen and Onions as B – antigen. 


Consider the ingredients as molecules attached over RBCs.


If a pizza has bell peppers over it, its A – pizza (or A blood group) 


If a pizza has onions, it will be B – pizza ( B blood group) 


If the pizza has both bell peppers and onions, it’s AB pizza ( AB blood group) 


And if both onions or pizza are absent, it’s O Pizza (O blood group) 


But wait! There is one more possibility! 


What if even pizza sauce is absent? 


Yes, you guessed it right. That would be Bombay pizza ( Bombay blood group). 


Biology behind Bombay blood group. 


There are a number of layers of molecules attached to RBC. 


On the surface of RBC, a precursor (parent) chain is present over which H, A, B antigens are attached. H antigen is the precursor/foundation for the attachment of A and B antigens. 


So if the H gene is not expressed and H substance is not formed, A or B antigens cannot attach to the red blood cell ( Little similar to how pizza sauce is necessary before we put onions or Bell peppers) 


Also, as pizzas have many more ingredients (chilies, olives, cheese, etc), red blood cells also have a variety of molecules attached over it. We simply classify them on the basis of antigens (the main ingredients!)


Why usual blood test can’t find the Bombay blood group? 


Most of the laboratories can identify blood groups as A, B, AB, and O but not Bombay blood group. 


That’s because, they are just testing if there are onions or bell peppers, both or none on the pizza? They do not check if there is pizza sauce present or not. 


So, if they don’t find A antigen (bell peppers) and B antigen (onions) over the pizza, it would show them as O blood group (O – pizza). They would not check for H-antigen (pizza sauce) and thus can’t recognize Bombay blood group over O blood group. 


So, if you have O blood group, Chances are you might have Bombay blood group! 


People with Bombay blood group are Universal donors. 


People who have Bombay phenotype can donate blood to any member of the ABO blood group system, but they cannot receive blood from any member of the ABO blood group system (because Bombay blood group have antibodies against all other ABO types), but only from other people who have Bombay phenotype. 

How Bombay blood group got its name? 


In 1952, doctors at KEM hospital in Bombay (Mumbai) came across a patient whose blood group wouldn’t match with any of A, B, AB or O. After many trials, they came to know that blood cells are missing H – antigen and that’s why it is different from other blood groups. As it was in Bombay, doctors named it as Bombay blood group. 


And that’s about Bombay blood group. Let me know in the comments what do you think about it. 

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