Although more than 400 blood groups have been identified, the ABO Rh blood group systems remains the most impoant in clinical medicine because:

Blood group genes are inherited in a Mendelian manner and are mostly located on autosomes. Most of the blood group genes are expressed in a codominant manner. In blood transfusion practice, most impoant blood group systems are ABO and Rh. Because, A, B, and Rh D antigens are the most immunogenic (i.e. capable of eliciting a strong antibody response on stimulation) and their auto antibodies can cause destruction of transfused red cells or induce haemolytic disease of newborn (HDN). ABO antigens are also impoant in organ transplantation. Blood group systems (International Society of Blood Transfusion or ISBT, 2008) Traditional name ABO Yt MNS Xg P1Pk Scianna Rh Dombrock Lutheran Colton Kell Landsteiner-Wiener Lewis Chido/Rodgers Duffy Hh Kidd Kx Diego Gerbich John Milton Hagen Cromer I Knobs Globoside Indian GIL Ok RHAG Raph