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 blood type, h/h or Oh is present in less than 0.0004% of the world’s population.

First discovered in 1952 by Dr. Y G Bhide, the Bombay Blood type is largely recognised as the rarest blood group in the world. In an observation of the blood type’s reaction with the commonly recognised blood phenotypes, it was found that the Bombay Blood type contained a previously unknown antigen – H.

Antigens A and B are both found to be made from antigen H. So, people with the Bombay phenotype can donate blood but not serve as recipients.

The Bombay phenotype is allowed to donate red blood cells to any of the blood types within the ABO phenotype realm, the reverse, however, is not possible. People with the Bombay phenotype can only receive blood from their own group because of the antigen reactions that may cause defects in the receiver’s immunology. 

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.

Masthead Source: jacobinmag.com, Feature Image Source: bloodlocator.com