Bombay Blood Group

What is Bombay blood group?

Bombay blood group is the rarest blood group. First found in Bombay (Mumbai) in India 1952, hence called Bombay blood group.  It is observed to occur in 1 out of every 250,000 people except in parts of India where the incidence has been observed to be as much as 1 in every 7,600.  

Why is it called HH Group?

It is also called the HH group. The peculiarity is that they do not express the H antigen. As a result, they cannot form A antigens or B antigens on their red blood cells. Thus they can donate blood to anybody with ABO grouping but can receive blood only from Bombay blood group people.  

What are the other type of common blood groups?

To understand Bombay blood group, we must understand the details of blood grouping. The four most common blood groups are A, B, AB and O. 

 When we say someone has blood group A, it means that the person has antigen of type 'A' and antibody of type 'B' in his/her blood. People with AB have both antigen A and B in their blood and no antibodies. People with O blood group have only antibodies A and B and no antigens. However, what is not generally known is that all these groups have an antigen H in the blood as well. There are very few people who do not have this antigen H also in their blood. Instead they have antibody H because of which no other blood can be given to them.

Why has it shot into news? 

There was acute shortage of it in Mumbai recently. 

An unofficial registry for Bombay blood group lists over 350 donors across India. But at any time there are only 30 active donors available. This group is generally not stored in blood banks, mainly because it is rare and the shelf life of blood is 35-42 days. Whenever there is a demand for a Bombay blood group patient, a donor is required very urgently. Sometimes, facilities need to be created for transporting the donated blood from one city to another.