Blood groups were discovered in 1900 by an Austrian scientist Karl Landsteiner.
They come on four types A,B,AB and O.
The blood group actually indicates the antigens found on the red blood cells.
Broadly, there are two types of antigens A and B.
Blood with A antigens is called A group
While blood with B antigens is called B group.
If the blood has both antigens it is called AB group. If it has neither, it is called O group.
But in 1952 a trio of doctors at Bombay’s KEM hospital came across a patient whose blood would not match with A,B, AB or O.
It turns out that antigens A and B have an ancestral called H. All the three of them A,B and H were missing in KEM hospital patients blood.
After trying 160 unsuitable donors the doctors finally found a matching donor. Since he was from Bombay, they called it the Bombay blood group.
A person with the Bomabay Blood Group is a universal donor. But they can’t accept only from same group.
Since sometimes they can get labelled as the ‘O group’ a specify testing for antigen H will confirm if it indeed the Bombay blood group.
This is so rare that Bombay Blood Group found only four out of one million people. It is so rare that only 400 registered donors in the country have this blood type.
Since it is not certain, hence we can labelled it as O-ve blood group.