Non-invasive prenatal diagnosis of fetal RhD by using free fetal DNA

Abstract

Objective: Anti-D immunoglobulin is applied to all pregnant women having Rh]) incompatibility to prevent hemolytic disease of the newborn. The aim of this study is to determine fetal RE]) status in the Rh incompatible pregnancies with an non-invasive technique; free fetal DNA isolation from maternal circulation. In the case of Rh incompatibility especially with a history of previous fetal anemia, it can be beneficial to know Rh status antenatally in terms of monitoring fetuses with Rh positive [RhD(+)] status consciously. Materials and Methods: Total free DNA was isolated in 50 Rh negative [RhD()] pregnant women, who had Rh]) alloimmunisation with their husbands. The gene in isolated DNA was investigated with TagMan prob and real time PCR by using primers belonging to exon 7 of the RhD gene. Results: The authors analyzed 50 RhD() women by using quantitative real time PCR technique. Five of them were RhD() and the rest of them were found to be RhD(+). After birth one of the infants who were analyzed as RhD(+) were found to be RED(). Conclusion: The detection of fetal RED status by using a non-invasive method from maternal circulation was found to be possible. Assessing fetal RED status non-invasively by using free fetal DNA in maternal blood will be cost-efficient, avoiding unnecessary indirect Coombs test and unnecessary Rhogam applications that is used in RH incompatible pregnancies. This study will throw a fresh light on prenatal diagnosis.