Zdravniški Vestnik (Dec 2004)
DETERMINATION OF FETAL BLOOD GROUP IN PREGNANCY
Abstract
Background. Prenatal diagnostics with the genotyping using the PCR analysis of the fetal DNA holds an important place in modern gynaecology. Lately, noninvasive fetal genotyping became feasible after fetal DNA was proven and isolated from the peripherral blood of the mother.Methods. Peripherral blood samples of ninety-six RhD negative women in their 23–33 week of pregnancy were collected and the DNA of the fetus isolated with the modified method of Finning et al. Fetal RHD genotype was than determined with real time PCR method using the ABI Prism 7900 Sequence Detection System. The presence of the three parts of the RHD gene, intron 4, exon 7 as well as 10, was assesed. In order to confirm the presence of fetal DNA, the presence of the SRY gene was used with male fetuses. If the PCR reaction results of the RHD and SRY gene were negative, we assumed that the fetus was a female whose RhD was negative. In order to verify that, a presence of eight chosen polymorphic alleles was determined from the the DNA samples of the mother and from her plasma, thus indirectly confirming that it was the DNA of the fetus which was being tested.Results. In this research we accuratly predicted the genotype and gender of the fetuses of 96 RhD negative pregnant women from their peripheral blood. The predicted results of the research were compared with the actual gender and RhD phenotype of the newborn, that were determined at birth. Our accuracy in predicting the gender and the presence of the RHD gene using our real-time PCR method was 100%.Conclusions. We anticipate the fetal genotype, determined on the basis of the fetal DNA being present in the peripheral blood of the mother, to take on a leading role in prenatal investigations, especially in cases of RhD immunisation during pregnancy and in prevention of RhD immunisation with anti-D immunoglobulin in the 28th week of pregnancy.
