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. Copyright (c) 2005 John Wiley & Sons, Ltd.