Antenatal Rh prophylaxis is unnecessary for "Asia type" DEL women

Background: Generally Rh-negative patients need to be transfused with Rh-negative red blood cells. For pregnant women carrying Rh-positive fetus, the antenatal anti-D detection and Rh immunoglobulin prophylaxis are required worldwide. In East Asia, a RhD variant, termed "Asia type" DEL, was found in approximately 30% of apparent Rh-negative individuals. The antigenic and molecular properties of the DEL were previously defined. Few data discuss whether DEL could be immunized by D antigen clinically although DEL was reported arousing alloimmunization to true Rh-negative patients.

Study design and methods: To determine whether the DEL variant can be immunized to the D antigen, we retrospectively evaluated 104 Rh-negative pregnancies with allo-anti-D antibodies, and we also tracked 199 consecutive apparent Rh-negative pregnant women, with a history of gestations or parturitions but not subject to anti-D gamma-globulin prophylaxis, for evidence of allo-anti-D. The DEL variant was first excluded by ccee phenotypes and then identified through PCR analysis or sequencing.

Results: In the retrospective study, we expected to find 30 DEL variants, yet none of the anti-D alloimmunized women were DEL-positive. And in the second group, none of 44 DEL-positive women versus 38 of 155 (24.5%) true Rh-negative women (those excluding DEL) formed allo-anti-D.

Conclusion: The data indicate that the "Asia type" DEL variant does not appear at risk of alloimmunization to the D antigen. It strongly suggests that the antenatal Rh immune globulin prophylaxis is unnecessary for DEL women. Furthermore, it implicates that the "Asia type" DEL may be deemed Rh-positive safely for clinical transfusion therapy.