Noninvasive Fetal RHD Genotyping from Maternal Plasma Use of a New Developed Free DNA Fetal Kit RhD®
C. Rouillac-Le Sciellour, V. Sėrazin, Y. Brossard, O. Oudin, C. Le Van Kim, Y. Colin, Y. Guidicelli, M. Menu, J.-P. Cartron
Summary
Fetal RHD genotyping from maternal plazma was performed by real-time PCR amplification of exons 7 and 10 of the RHD gene and the amplified products were detected either with SYBR Green I Dye acf cording to our previously published method [Mol Diagn 2004; 8: 23-31] or with hydrolysis probes in a new Free DNA Fetal Kit RhD®. Plazma specimen from 300 RhD- negative pregnant women (between 10 to
weeks of gestation) were analysed and validation of the results was ascertained either by RHD genotyping on amniotic cells or by blood typing of the neonate at birth. We found 100% concordant results when comparing the two methods. Two false-positive but no false-negafive results were found. Thus, the sensitivity of the assay was 100% and the specificity superior than 99%. These data confirm the accuracy of fetal RHD genotyping on maternal plasma using the Free DNA Fetal Kit RhD®, thus allowing to propose non invasive PCR based fetal RHD genotyping for all RhD negative pregnant women and to restrict the use of anti-D immunoglobulins only to those bearing and RhD-positive fetus.
Keywords: Rhesus (Rh), RHD genotyping, Fetal DNA, Maternal plasma, Hemolytic disease of the newborns, Anti-D prophylaxis.