Just when you thought you knew all you needed to at this stage in the development of science, a medical marvel steps in to set the record straight. No points for you if you named all of the blood groups. But if we told you we missed out on one of the rarest blood groups in the world? A blood phenotype so rare that it shows up in no more than 4 in every million humans. Blood types are classified basically as combinations of the ABO phenotypes. These include all of the regular blood groups that we usually witness - A, B, O and AB. The compatibility and differences in the blood types rely on the different kinds of antigens and antibodies each contain, and their reaction with each other. This alongside other characteristics like the Rh factor.

The Bombay phenotype is usually found within close knit communities.

With as many as 0.01% of people from Mumbai who could be carrying the Bombay phenotype, the rare blood type is usually the result of both parents carrying a recessive allele which will result in the child having the h/h blood group. Close knit communities, or even inbreeding, seem to be the cause of the blood type.

Mumbaikars, get yourself checked out. Perhaps, you are a rare specimen.