A delayed and acute hemolytic transfusion reaction mediated by anti-c in a patient with variant RH alleles

The Rh system is the most complex of the human blood groups. Of the 55 antigens that have been characterized, the system’s principal antigens D, C, E, c, and e are responsible for the majority of clinically significant Rh antibodies. In the last few years, advancements in molecular testing have provided a wealth of information on the genetic diversity of the Rh locus. This case report describes a patient with variant RHD*DAR alleles inherited in conjunction with two compound heterozygote RHCE*ceEK/RHCE*ceAR alleles. The patient was previously alloimmunized to D, C, and E and possibly hr^S. Further transfusion of D–C–E–K– RBCs resulted in a suspected acute hemolytic transfusion reaction and the subsequent identification of anti-c. Monocyte monolayer assay testing suggests clinical significance with a range of 29.5–38.5 percent reactive monocytes. Immunohematology 2018;34:109-112.