Bombay blood group is the rarest of rare blood group. First found in Bombay (Mumbai) in India, hence known as Bombay blood group. It is probably occuring in 1 out of every 250,000 people except in parts of India. In India the incidence observed to be as much as 1 in every 7,600.
It is familiar as HH group. The strange thing is that they do not show the H antigen. As a result they cannot form A or B antigens on their red blood cells(RBCs). Thus they can donate blood to anyone with ABO grouping but can accept blood only and only from Bombay blood group people.
What is Bombay blood group?
To know Bombay blood group we must understand the key details of blood grouping. When we say someone has blood group A, it means that the individual has antigen of type A and also antibody of type B in his/her blood. People with AB have both of the antigen A and B in their blood and no antibodies. Individual with O blood group have only antibodies A and B and also no antigens. What is not commonly known is that all these groups have an antigen H in the blood as well. There are very few individuals who do not got this antigen H also in their blood. Instead they have antibody H due to which no other blood can be given to them.