Objective: A 77 year old female was admitted with a subdural hematoma requiring 1 unit of apheresis platelets. She was a study subject in the 1960s and was found to be Rhnull, along with another individual who previously served as a directed donor for her.
Methods: Serologic testing performed by the immunohematology reference laboratory (IRL) confirmed that the patient was Rhnull and expressed anti-Rh29 antibodies. While searching for red blood cells (RBCs) for possible transfusion, it was discovered that the individual from the original study had recently donated an autologous unit.
Results: The IRL discovered that the donor's antigen typing was r'r'. Testing had been performed using a molecular human erythrocyte antigen BeadChip (HBC). Due to the discrepancy between current and historical testing results, a donor segment was thawed and by tube testing confirmed to be Rhnull. A limitation of HBC is that many null phenotypes will be missed.
Conclusion: This case demonstrated that Rhnull evaluation of the donor required both serological and molecular methods.
Keywords: RHAG; Rh blood group system; antibodies to high prevalence antigens; antigen testing; antigen testing by DNA; complex antibody identification; high prevalence; null types; platelet transfusion.
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