Development of anti-D in a severe delayed hemolytic transfusion reaction due to DAU3, a partial D variant allele

The Rh blood group system, of which RHD is the most notable, is one of the most clinically important red blood cell antigen groups next to ABO.

In this case report, we describe a severe delayed hemolytic transfusion reaction caused by allo-anti-D in a patient with Sickle Beta Zero Thalassemia initially typed O RHD positive via standard serologic type and screen.

Further serologic testing revealed the development of an allo-anti-D, suggestive of a partial D phenotype. The patient was confirmed to carry the DAU3 allele using confirmatory molecular genotyping.

This case highlights the importance of timely identification and reporting of delayed transfusion reactions, especially in the context of prior sensitization events. Additionally, careful investigation of serologic patterns to identify partial D variants is important to optimize the clinical management of affected patients in the case of trauma, obstetrics, or operative care. We suggest the necessity of molecular testing in high-exposure patient populations to prevent adverse outcomes from unexpected allo-anti-D development.