Assimilation of red cell genotyping into routine practice. (A) Depicts one scenario for incorporating red cell genotyping into routine practice based on technology currently available. It is also possible DNA-based testing could be undertaken at the blood bank or another laboratory. (B) Depicts one possible future scenario, assuming genetic screening with DNA arrays to identify disease susceptibility will become routine and a genetic test capable of identifying those patients (responders) likely to make alloantibodies to blood group antigens will be available.