Karl Landsteiner discovered the ABO blood group system in 1901 and was awarded the Nobel Prize in 1930. His discovery found that if a red blood cell antigen is present, the corresponding antibody will not be present in a patient's plasma under normal conditions. The Rh blood group system, discovered by Dr. Y.M. Bhende in 1952, involves the presence or absence of the Rh antigen on red blood cells and is also known as the HH group.