Partial D phenotypes and genotypes in the Chinese population

Background: The D variant phenotypes are often categorized into weak D types and partial D types. Although the molecular basis underlying the partial D phenotype has been investigated in several races, data from Chinese populations are rare.

Study design and methods: We collected partial D samples from 1,274,540 blood donors, as well as from sporadic patients in the Chinese population, over a 4-year period. Samples with partial D phenotype were determined by commercial monoclonal anti-D panels and molecular methods. Blood samples with discrepant results of serologic and molecular methods were further investigated by polymerase chain reaction (PCR) with sequence-specific primers and nucleotide sequencing of RHD exons. The detection of antibodies was performed.

Results: A total of 44 samples with partial D phenotypes were confirmed. Molecular typing revealed five different known aberrant alleles as well as four new RHD alleles. As described previously, DVI represented the most frequent partial D type in China with a total of 36 samples. However, discrepant results were observed in four DVI samples with serotyping and genotyping (i.e., DVI category identified by D-screen test and grossly intact RHD gene identified by multiplex PCR). We also found four novel alleles, termed DFR-4, DCS-3, DCC, and DLX.

Conclusion: To date, this study presents the most comprehensive report on partial D in China. The distribution of partial D types in China was found to be complicated and polymorphic, whereas RhD genotyping of DVI-variant samples might give inaccurate results due to a relatively high incidence of RHD(1227G>A) in the Chinese population.