(P-IG-6) A Very Challenging Case with Partial D, Multiple Alloantibodies, and Warm Autoantibodies

Background/Case Studies: Partial D phenotypes occur in 0.2-1% of Caucasians, and ~ 20% are estimated to develop anti-D alloantibodies (AA). Cases involving partial D patients who develop anti-D, multiple AA, and warm autoantibodies (WAA) are challenging and rare.

Study

Design/Methods: This is a description of a 56-year-old man who presented with shortness of breath. His past medical history included chronic HCV and myelodysplastic syndrome with worsening pancytopenia. Orders for Type & Screen and six red blood cell (RBC) units were received for symptomatic anemia with hemoglobin of 4.4 g/dL.



Results/Findings: The patient typed as group O with mixed field reaction with the anti-D reagent by
automated gel technology (AGT) and D-negative by tube method. The antibody screen (AbS) was positive. The following AA were identified in the patient’s plasma using the PEG-IgG method: anti-D (3+), anti-C (1+), and anti-Fya (3+). No additional AA against common RBC antigens were detected. The direct antiglobulin test was weakly positive with IgG, and negative for C3 fixation. The eluate demonstrated a panagglutinin reactive with all reagent cells tested, including D- C- K- Fy(a-) Jk(a-) reagent red cells.

Further investigation revealed that his historical blood type was O Rh (D)-positive with negative AbS and he was transfused with three units of O Rh (D)-positive units. Subsequent testing identified anti-D, anti-C, anti-Fya, anti-Jka AA, and WAA. Subsequent serological testing in the following months showed a strong (4+) anti-D reactivity by AGT. The HEA RBC Genotype demonstrated that the patient’s predicted phenotype is partial D (with c.674C >T single-nucleotide variant (SNV) associated with two variants, RHD*08N.01 and RHD*30) and C-E+c+e+ K-k+Kp(a-b+) Js(a-b+) Fy(a-b+) Jk(a-b+) M+N+S+s+U+ Lu(a-b+). He was transfused with Rh (D)-negative and fully phenotype-matched RBCs.

Conclusions: We report a rare case of a patient initially typed as Rh (D)-positive with anti-D, multiple AA and WAA, who was confirmed to be partial D. The case highlights the limitations of serological testing and the importance of accurate identification of the D phenotype via prompt molecular testing. Precise determination of D phenotype is critical for appropriate blood selection for all patients and especially important for preventing anti-D formation in the reproductive age group.