Overt immediate hemolytic transfusion reaction attributable to anti-Wr^a

Wr^a is a low-prevalence antigen. Anti-Wr^a is a relatively common antibody present in approximately 1 in 100 healthy blood donors. Anti-Wr^a is reported to cause different degrees of hemolysis in transfusion and in HDN, ranging from benign to severe. This report describes an acute overt hemolytic transfusion reaction in a patient whose serum contained anti-Wr^a and who received a Wr(a+) RBC component. Immunohematology2008;24:113–115.