Value of DNA-based assays for donor screening and regulatory issues

Hemagglutination, the gold standard method to detect the presence or absence of blood group antigens on RBCs, has served the transfusion community well for decades. It is simple, and, when done correctly, it has a specificity and sensitivity that is appropriate for most testing in the vast majority of patients requiring blood transfusion. The limitations of hemagglutination for screening donor blood include that both testing and data entry are labor-intensive, that the required antibody is not always commercially available, and that it may be limited in volume, weakly reactive, or costly. These scenarios can make it difficult to screen for large numbers of antigen-negative blood donors. The knowledge of the molecular bases of blood group antigens makes it possible to screen donors to predict their antigen status. High-throughput platforms provide a means to test relatively large numbers of donors, thereby opening the door to change the way antigen-negative blood is provided to patients. This review discusses testing for blood group antigens by hemagglutination and bead chip technology. It also reviews regulatory issues, including validation and training, and suggests an algorithm for screening and confirming blood types of donors.