Identification of pregnant women with DFR genotype and discussion of prenatal examination strategy

Abstract

Objective To identify three cases of pregnant women with the D variant phenotype using serological and molecular tests, and discuss the strategy of prenatal examination. Methods The peripheral blood samples from three pregnant women with the D variant phenotype were collected. RhD variant phenotype was determined using routine serological methods with two different kinds of monoclonal anti-D. The serological characteristic for the epitope of D antigen was further analyzed using the commercial panel anti-D reagents (D-Screen, Diagast). The hybrid RHD-CE-D allele was analyzed by the Multiplex Ligation-dependent Probe Amplification (MLPA) assay and polymerase chain reaction with sequence specific primers (PCR-SSP) method. Further Sanger sequencing of RHD gene exons was also performed. Results DFR phenotype was primarily determined by serological characteristic for the epitope of D antigen. RHD*DFR2/01N.01(n=2) and RHD*DFR1/1227A(n=1) genotypes were identified by the MLPA assay, PCR-SSP and Sanger sequencing. Conclusion Two pregnant women with RHD*DFR2/01N.01 genotype should be treated as D negative patients clinically, while the pregnant woman with RHD*DFR1/1227A genotype can be treated as Asia type DEL to avoid unnecessary antibody screening and anti-D prophylaxis.

Keywords

• dfr
• hybrid rhd-ce-d allele
• d variants
• rh blood group system.