Allo-Anti-D vs. Auto-Anti-D in Females of Child Bearing Years: The Critical Role of Rh Genotyping

Abstract

Abstract Introduction/Objective In females of child-bearing years, establishing accurate D-antigen identification is critical; this can be further complicated when a D+ patient seemingly develops an allo-anti-D. We present a unique case series highlighting the critical role of genotyping in distinguishing allo-anti-D vs. auto-anti-D. Methods/Case Report Case 1: An African American, 21-year-old, nulliparous female with a history of sickle cell disease presented for transfusion. The patient’s blood type was O, Rh Positive on multiple testing platforms (ORTHO VISION® Analyzer, 1001 US Highway 202, Raritan, NJ 08869, and Immucor, Inc., 3130 Gateway Drive, Norcross, GA 30071). On type and screen performed by manual tube testing, anti-D was identified. DAT IgG was weakly positive. The patient’s phenotype had been performed previously, and she was negative for both the C and E antigens. Genotyping results: RhD homozygote. RHD*DAU0 and RHD*DIVa type 3. The patient was determined to have auto-anti-D formation. Case 2 A 42-year-old female presented for routine prenatal care. At a previous facility, the patient tested as D+ and typed as O, Rh Positive (ORTHO VISION® Analyzer). An anti-D pattern was identified. Due to the patient’s Rh+ history and early pregnancy status, no Rh immune globulin was administered. A sample was sent to the reference laboratory which confirmed D+ status and a pattern of anti-D. The current titer was 8. Genotyping results RhD hemizyote. Positive for hybrid Rhesus box associated with deletion of RhD and RHD*DIVa, Go(a+). The patient was determined to have an allo-anti-D. Results (if a Case Study enter NA) NA Conclusion These two cases highlight the importance of RhD genotyping for resolutions of anti-D. In case 1, the patient had two altered alleles. While DIVa, type 3, is associated with anti-D formation, she also expressed RhD*DAU0 which is not considered to lack D proteins. We report the rare association between DAU0 expression and auto-anti-D formation.