Diagnostic utility of RHD-gene detection in maternal plasma in the prophylaxis of feto-maternal Rh-incompatibility

Abstract

Objectives: The aim of the study was analytical validation of prenatal noninvasive fetal RHD detection in maternal plasma and the preliminary assessment of its clinical utility. Introduction of this noninvasive test into routine diagnostic use is important for more rational and safe immunoprophylaxis. Material and methods: RHD gene was detected using real-time PCR. Primers and probes complementary to sequence on exons 7 and 10 were chosen. Samples with RHD-negative results were examined with additional tests to confirm the proper isolation of cell-free fetal DNA (cffDNA). For male fetuses, the presence of fetal DNA was confirmed by detection of the male genetic marker (SRY gene) using Quantifiler DuoR kit. In the case of SRY-negative result we used mini SGM test, which is based on the detection of short-tandem repeat polymorphism differences between maternal and fetal DNA. Results: Diagnostic accuracy of RHD test was 96.82%, while diagnostic value of SRY determination was lower (87.50%). Mini SGM test was able to confirm the presence of fetal DNA in 77% of the cases. Conclusions: Effectiveness of the proposed procedure of prenatal noninvasive RHD determination and cffDNA confirmation is high, on condition proper control samples and suitable verifying tests are used.