The Rarest Blood Type In the World

A, B, AB and O are the four most common blood groups, and while RH is rare, there's an even more rare blood type. Blood group H/H was first discovered in 1952 at Bombay, India. The rare blood group is deficient in expressing antigen H. This means that the RBC has no antigen H. All around the globe, the instance of a human having a HH blood type is one in four million, but in India one in 10,000 people are born with this blood type, and that’s because it’s genetically passed. People with this blood type can receive only their blood type.