The R_o^Har antigenic complex is associated with a limited number of D epitopes and alloanti‐D production: a study of three unrelated persons and their families

Abstract

BACKGROUND: the RoHar antigenic complex has been characterized serologically by difficulties in D typing, weak e expression, lack of G antigen, presence of Rh33, a low-frequency Rh antigen, and, more recently, a second low-frequency antigen, FPTT. Allocation to one of the partial D catagories was not considered because of the unuaual reactions of RoHar cells and because anti-D production was not observed in RoHar persons. STUDY DESIGN AND METHODS: Three unrelated RoHar donors and their families were studied in detail with special emphasis on D epitope mapping, e and G typing, and screening for antibodies. RESULTS: Only D epitopes 5 and 6/7 were demonstrable, and D epitopes 1, 2, 3, 4, 8, and 9 seem to be absent in the RoHar complex. In one individual, the presence of alloanti-D with limited specificity, not reacting with RoHar red cells of other individuals, was found 6 months after a second D+ pregnancy. CONCLUSION: The finding of alloanti-D in an RoHar r person supports the concept that the D characteristic of this phenotype is a partial D antigen, which is consistent with the presence of the limited number of D epitopes found in epitope mapping. As has been suggested for other partial D antigens, RoHar individuals should be regarded as D- for the receipt of blood, and pregnant RoHar women who have had D+ pregnancies should receive anti-D prophylaxis.