Pedigree analysis for the rare RHD DVa allele: serological and molecular studies

Until now, worldwide more than 80 different alleles producing weak D phenotypes have been identified. Here we identified rare RHD DVa alleles in Chinese individuals associated with weak expression of D antigen and an RHD phenotype resembling DVI. Multi-monoclonal anti-D antibodies were used to identify the RHD phenotyping for rare RHD DVa. RHD genotyping was used to confirm the presence of RHD exons and identify RHD, RHCE hybrids and exon deficiencies. Sanger sequencing was used to identify nucleotide polymorphisms in RHD exons. Pedigree analysis demonstrated RHD DVa allele alterations of 667 T>G, 676 G>C, 697 G>C, 712 G>A, 733 G>C, 744 C>T and 1227 G>A, which means the proband's alleles were RHD DVa-3 [also called RHD-CE(5)-D] and 1227 G>A. The results also demonstrated RHD DVa and the original RHD Va allele without 1227 G>A. The study suggests that RHD phenotyping is a superior strategy for the molecular analysis of RHD variant in Chinese subjects, and for understanding related polymorphisms and mutations.