Serological profiling and molecular characterization of D variants in Chengdu blood donors.

Background: Some D variant individuals are at risk of developing anti-D immunization when exposed to RhD-positive red cells. Therefore, accurate typing of D variants is essential to ensure the safety of clinical blood transfusion practices. The aim of this study was to investigate the serological profiles and molecular characteristics of D variants among Chengdu blood donors and to establish a more cost-effective RHD genotyping strategy tailored for the Chinese population.

Methods: During the period from 2019 to 2022, samples from Chengdu blood donors typed as RhD-negative with IgM anti-D using the microplate method underwent additional RhD typing with a panel of monoclonal anti-D reagents using both the micro-column gel card technique and the saline tube method. Samples that could not be classified as either RhD-positive or RhD-negative were genotyped using the PCR-SSP assay and Sanger sequencing. RHD zygosity status was determined by assessing the presence or absence of hybrid Rhesus boxes. Alloantibody screening was conducted to evaluate the risk of anti-D immunization.

Results: Three variants RHD*15, RHD*DEL1, and RHD*06.03.01 accounted for 61% of D variants identified in our study. Each of these were studied for distinct reaction patterns with a panel of anti-Ds. Additionally, eight previously reported D variant alleles, including RHD*01W.95, RHD*01W.72, RHD*01W.12, RHD*01W.18, RHD*01W.39, RHD*01W.67, RHD*01W.71, and RHD*01W.960A were observed sporadically. Furthermore, two novel alleles characterized by a nucleotide change (c.283G>T) and a nucleotide change (c.84C>G) respectively were identified. No cases of anti-D formation were detected in the D variant samples.

Conclusions: The spectrum of D variants identified in this study highlights the genetic diversity in the Chengdu blood donors, underscoring the need to incorporate these D variants into RHD genotyping strategy tailored specifically for the Chinese population. Comprehensive analysis of serological reaction patterns across these D variants would help guide molecular testing strategies and enhance genotyping cost-efficiency.