AB blood group
The AB blood group is displayed in individauls who's red blood cells display both the A and B antigen. This is a rare blood group type, AB negative being the rarest. [1]
The ABO gene encodes for the formation of glycotransferases that add N-acetylgalactosamine and galactose to teh H antigen already present on the the red blood cells, to form both A and B antigens.[2]
The individual with the AB blood type does not coantin any antibodies against A and B antigens. This is so the immune system does not attack the red blood cells.[3]