Non-invasive fetal RHD and RHCE genotyping from maternal plasma in alloimmunized pregnancies.

BACKGROUND: In this prospective study, we assessed the feasibility of fetal RH genotyping by analysis of DNA extracted from maternal plasma samples of alloimmunized pregnant women using real-time PCR and primers and probes targeted toward RHD (exon 7 and exon 10) and RHCE (intron 2 and exon 5) genes.

METHODS: We analysed 23 alloimmunized pregnant women (16 anti-D, 5 anti-D + C, 2 anti-E) at risk of haemolytic disease of the newborn (HDN) within 11th and 37th week of pregnancy and correlated the results with serological analysis of cord blood.

RESULTS AND CONCLUSION: Detection of the presence of the RHD gene, the C and/or E alleles of the RHCE gene in maternal plasma samples is highly accurate and enables implementation in a clinical diagnostic algorithm for following pregnancies at risk for HDN. The absence of RHD gene, the C and/or E alleles of RHCE gene in the current pregnancy excludes the risk of HDN caused by anti-D, anti-C and/or anti-E alloantibodies and the performance of invasive fetal-blood sampling.