Quantitative analysis of fetal RhD genotyping with fetal DNA from RhD-negative maternal plasma / 中华检验医学杂志

ABSTRACT

Objective To explore the feasibility of fluorescence quantitative PCR(FQ-PCR)in prenatal diagnosis of the fetal RhD genotyping using free DNA from RhD-negative pregnant women.Methods The fetal RhD gene was amplified from 78 RhD-negative pregnant women with single fetus maternal plasma (gestation from 11 to 40 weeks).Rhe existence of fetal DNA was confirmed by amplification ofnine different polymorphic short tandem repeat loci(STR)and sex-determining region Y chromosome(SRY)gene.Exon5,7,10 and intron 4 were amplified by real-time polymerase chain reaction with TaqMan probe.The results of fetal RhD genotyping were evaluated retrospectively by the serologic analysis of infant cord blood.Results Among the 78 specimens,the SRY positive signals were detected from samples of 41 and were all identified male fetal through 8ex observation after newborn infants delivered from the women enrolled.The mean concentration of SRY gene reached(214.7±120.9)eopies/ml.RhD genotyping results of 70 cases were in complete concordance with the resets through serological detection of fetal cord blood after delivery.In addition,5 cases were false-positive.3 cages were considered inconclusive.The coincidence rate was 90%(70/78).From 5 false-positive cases,4 cases were identified as RhDel phenotype by detecting RHDl227A allele gene.The final accuracy rate of FQ-PCR was 95%(74/78)in the fetal RhD genotyping.Conclusion FQ-PCR analysis for noninvasive prenatal of fetal RhD genotyping could be useful in prevention and diagnosis of hemolytic disease of newborn.