Moderate hemolytic disease of the newborn (HDN) due to anti-Rh17 produced by a black female with an e variant phenotype

The Rh blood group antigen e is of high incidence and has many epitopes. Partial expression may occur, more commonly in black persons. Individuals with e variant phenotypes can make antibodies to epitopes they lack. While some of these antibodies may be specific for an antigen, e.g., hr^B, others, like anti-Rh17 (anti-Hr_o), show broader specificity, compatible only with D–– and Rh_null red blood cells (RBCs). Anti-Rh17 in persons of the D–– phenotype has been reported to cause mild to fatal HDN. We report an example of anti-Rh17 produced by a black female with an e variant RBC phenotype that caused moderate HDN. A panel of seven monoclonal anti-e demonstrated her RBCs carried a variant e antigen, and her genotype was RHD, RHce by PCR-RFLP analysis. Amniotic fluid with ΔOD₄₅₀ values from 30 to 35 weeks’ gestation predicted moderate HDN probability by the Liley method. At 38+ weeks, a viable 3165 g female infant was delivered. The infant’s direct antiglobulin test was 2+ with anti-IgG. Total bilirubin rose to 14.2 mg/dL within 48 hours. Indirect bilirubin peaked at 14.7 mg/dL. The bilirubin responded to triple phototherapy. The infant was discharged on day 6. Potential for infant morbidity due to anti-Rh17-mediated HDN and the importance of specifying risks to women with this antibody if they contemplate pregnancy are discussed. Immunohematology 2002:18:40–42.