Lost in the Ds: Unexplained Loss of Rh(D) Antigen Expression By Serological Testing In Two Patients

Abstract Introduction/Objective While the loss of ABOH antigens has been well documented, reduced-to-absent expression of the RHD antigen is comparatively rare. Here, we describe two cases with D antigen loss presenting associated clinical settings, smear results, and red blood cell (RBC) genotyping findings to elucidate this unusual phenomenon. Methods/Case Report Cases (n=2) were retrospectively reviewed based on discovery during routine serological testing in our Blood Bank. RhD blood typing was performed via gel methods [Grifols, Los Angeles, CA]. Clinical information and laboratory data were extracted via the electronic medical record. Case 1 is a 79-year-old female with metastatic breast cancer. She initially typed as D positive (4+) in at least two separate analyses, but her D front type progressively became weaker until turning entirely negative after several weeks. Spherocytes and stomatocytes were present on her peripheral blood smear. This patient received 10 D+ red blood cell (RBC) units without anti-D formation. RBC genotyping revealed traditional “dce” by standard polymerase chain reaction (PCR). Case 2 is a 61-year-old male with a history of pre-B acute lymphocytic leukemia post-stem cell transplant, myelodysplastic syndrome, and progressive loss of D antigen expression (4+ to 0). Standard RBC genotyping revealed “Dce” by PCR. The peripheral blood smear was significant for RBC anisopoikilocytosis with increased stomatocytes, spherocytes, and ovalocytes. Results (if a Case Study enter NA) NA Conclusion The disappearance of the D antigen is rare, and our experience suggests an association between malignancies (both hematopoietic and non-hematopoietic) and D antigenic loss. Beyond these disease associations, however, loss of RhD is not otherwise readily explained in either case. Further analysis to test for other RHAG and RHCE mutational variants is an ongoing area of investigation in these cases, as more sensitive testing may reconcile the traditional PCR results with our initial detection of the D antigen.