Unraveling the mystery of e variant: Is it autoimmune or alloimmune?

The largest and most diverse blood group system is the Rh system. Numerous RH alleles lead to variable morphologies, which frequently make it tougher to differentiate between auto- and allo-antibodies in recipients with anti-Rh antibodies when their own corresponding Rh antigen is present. We present a noteworthy case involving a 45-year-old female patient who tested positive on the antibody screen. The patient exhibited inconsistent reactions during antibody identification, suggesting the potential presence of either an autoantibody or an alloantibody targeting the RHCE variant. Double alloadsorption, use of select cells, and consideration of ethnic background aided in the correct identification of allo anti-e in e variant case. This case highlights the clinical relevance of RHCE variants, particularly in patients of African descent, where partial e antigen expression is more prevalent and can result in serologic discrepancies and alloimmunization.