Abstract
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 hrS. 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.