Identification of genetic polymorphisms that predict responder/non-responder profiles to the RhD antigen

Abstract

Background: Regular plasma donors who produce high titre anti-D immunoglobulin (Ig) are overseen by the Australian Red Cross Blood Service RhD Program. New donors to the program are immunised with small amounts of RhD-positive RBCs, whilst donors who have developed anti-D due to previous RhD-incompatible blood transfusion or pregnancy are boosted with RhD-positive RBCs to maintain a high level of serum anti-D Ig. A significant proportion of primarily immunised individuals do not respond to RhD immunisation and are therefore unnecessarily exposed to the risks involved in RBC sensitisation.

Study design and methods: We genotyped 184 anti-D donors for ∼9000 immunological and inflammatory genetic polymorphisms on an Affymetrix GeneChip, and validated the results with a High-Resolution Melt analysis assay. We built and validated a predictive logistic regression model using High Responder and Non-Responder anti-D donors that incorporated highly-associated polymorphisms and gender.

Results: High Responder and Non-Responder profiles in anti-D donors were significantly associated with a shortlist of 13 genetic polymorphisms and sex of the donor. The derivation of a logistic regression model showed an accuracy rate of 92.6% that was subsequently validated as 60.0% with an independent set of donor samples.

Conclusion: This study has developed a logistic regression model and a genotyping assay that can predict the responder profiles of anti-D donors and could potentially be applied to new donors and transfusion-dependent patients in a clinical setting. Additionally, target polymorphisms identified in immunological genes could help to elucidate the immunomodulatory pathways regulating the immune response to the RhD antigen, and to other RBC antigens.

Keywords: High-Resolution Melt (HRM); Immunoglobulin (Ig); Red blood cell (RBC); Single nucleotide polymorphism (SNP).