Non-invasivefoetal RHD, RHC and RHE genotyping from maternal plasma in RhD negative pregnancies

Overview

In this prospective study,we assessed the feasibility of foetalRHD,RHCandRHEgenotyping by analysisof DNA extracted from maternal plasma samples collected from RhD negative pregnant women usingRQ-PCR and primers and probes targeted toward RHD and RHCE genes.We analysed 29 RhD negativepregnant women within 14th and 40th week of pregnancy and correlated the results with serologicalanalysis of cord blood after the delivery. Non-invasive prenatal foetal RHD exon 7 and exon 10genotyping analysis of maternal plasma samples was in complete concordance with the analysis of cordblood in 29 out of 29 RhD negative pregnant women delivering 13 RhD positive and 16 RhD negativenewborns. Non-invasive prenatal foetal RHC exon 2 genotyping was well performed in 25 out of 25 Rhchomozygote pregnant women delivering 8 RhC positive and 17 RhC negative newborns. Similarlynon-invasive prenatal foetal RHE genotyping was well done in 29 out of 29 Rhe homozygote pregnantwomen delivering 5 RhE positive and 24 RhE negative newborns. Foetal RHC and RHE genotyping inRhD negative pregnancies is very valuable, since in case of identification of RhD negative fetussimultaneous amplification of another paternally inherited allele (RhC or RhE positivity) proves thepresence of foetal DNA in maternal circulation. We recommend to perform simultaneous foetal RHD,RHC and RHE genotyping in alloimunised RhD negative pregnancies with certain phenotypes (ccee,ccEe, Ccee).

Key words:
foetal DNA, haemolytic disease of newborn, quantitative real time PCR, maternal plasma,RHD gene, RHCE gene