The human blood type inheritance

The presence or absence of two main antigens-antigen A and B. There are four main blood groups, namely, blood group A, B, AB and O. Antigens A and B determine whether blood groups are compatible or not during blood transfusion. The absence of antigens on the red blood cells gives blood group O. Further, antigen A has antibody b while antigen B has antibody a, which react against incompatible antigens to bring about agglutination of red blood cells and could bring about death in cases of unmatched transfusion (Daniels 13). Rh-positive individuals have the D-antigen while the Rh-individuals lack D-antigen on their RBCs (Daniels 182). The anti-Rhesus antibodies, unlike the ABO system, are absent in the blood of Rh-negative individuals until their circulatory system is exposed to the Rh-positive red cells.

Other antigen systems include the MNS, the Kell system, the Duffy system, the Lutheran system and the Kidd system, each of which plays a significant but minor role as compared to the ABO and Rhesus antigen systems as postulated by Daniels (8). The gene that codes for the ABO blood group is found near the telomere of the longer arm of chromosome number 9 and can be identified by quantitatively assaying adenylate kinase or (AK-1) of the red cells. The first gene transfer agent (GTA) was isolated and purified in 1990 and this was followed by cloning cyclic DNA which represented red cell A-antigen transferase mRNA(Daniels 37). Serological tests on blood group AB will, therefore, exhibit the characteristics of both blood groups and persons with this kind of blood are referred to as universal recipients (Daniels 5).