Blood type or group is a medical term. It describes the type of blood a person has. It is a classification based on the presence or absence of inherited antigenicsubstances on the surface of red blood cells (RBCs). There are a number of human group systems. Of these systems, the ABO blood group system and the Rhesus blood group system are the most important. In this system the presence or absence of the A-antigen, the B-antigen and the RhD-antigen are determined.
The Rh group system consists of 49 defined blood group antigens, among which the five antigens D, C, c, E, and e are the most important. Additionally it is name after the Rhesus monkey where they were first discovered. Rh is an inherited trait, which refers to a protein on the surface of an individual’s red cells. The Rh factor is separate from, and in addition to, ABO groups.
The Rh factor is either present on individual’s red cells or it is not. Rh positive means the factor is present. Rh negative means it is not present. In transfusions it is important that the donor and recipient have the same Rh factor and same blood group.
Rhnull individuals have no Rh antigens (no Rh or RhAG) on their red cells. This rare condition basically has been called “Golden Blood”. As a consequence of Rh antigen absence, Rhnull red cells also lack LW and Fy5 and show weak expression of S, s, and U antigens. Red cells lacking Rh/RhAG proteins have structural abnormalities and cell membrane defects that can result in hemolytic anemia. Only 44 individuals have been report to have it worldwide. Only 9 active donors have been report. Its properties make it attractive in numerous medical applications, but scarcity makes it expensive to transport and acquire.