Scientists Discover , New Set of Blood Types.br The most commonly known blood type br groups include A, B, O and Rh.br But 'The Hill' reports that there are dozens more.br A group of scientists, who published their study in the journal 'Blood,' have discovered br a new blood group called Er.br 'The Hill' reports that it is the br 44th blood group to have been found.br The blood group consists of five Er antigens that stem from genetic variations in the Piezo1 protein.br When antibodies match Er antigens, they can attach to them, which can cause immune cells to attack mismatched cells. .br 'The Hill' reports that while the Er antigen had already br been discovered, this is the first time that different br mutations of the antigen have been detailed.br 'The Hill' reports that being aware of possible differences in Er group compatibility may help health care workers to properly diagnose a patient. .br Discovering a new blood group system is like discovering a new planet.