Molecular and serological analysis of the D variant in the Chinese population and identification of seven novel RHD alleles

Abstract Background The molecular basis of the D variant phenotype in the Chinese differs greatly from that of the Caucasian. Adapting a specific D typing strategy to the spectrum of prevalent RHD variant alleles is necessary. Study Design and Methods Blood samples with ambiguous D phenotypes were collected in the Southern Chinese population. A special three‐step typing strategy was applied. First, the common DVI type 3 was identified from epitope profiles of D antigen. Then, another common weak D type 15 ( RHD*845A ) was identified by epitope profiles of D antigen and Sanger sequencing of RHD exon 6. Finally, the remaining D variants were genotyped mainly by Sanger sequencing. For the novel RHD alleles in the coding region and exon–intron junction, in vitro transfection and minigene splicing assays were performed, respectively. The anti‐D investigation was performed. Results DVI type 3 (65/253, 25.7%) and weak D type 15 (62/253, 24.5%) were common Chinese D variants, and RHD*960A , DFR , RHD*weak D type 25 , 72 , and 136 were frequent variant RHD alleles. Besides, twenty‐two sporadic and seven novel RHD alleles ( RHD*188A ; RHD*688C ; RHD*782 T ; RHD*1181C ; RHD*165 T, 993A ; RHD*148 + 3G > T and RHD*1227 + 5G > C ) were identified. The deleterious effect of the novel RHD alleles on D antigen or mRNA expression was confirmed. Anti‐D was detected in two DVI type 3 pregnant women. Discussion The three‐step typing strategy provides an effective approach for Chinese D variant typing. It can be anticipated that commercially available RHD genotyping kits have limitations for testing Chinese D variants, as some of the frequent variants are not interrogated.