Fetal <i>RHD</i> Genotyping in Maternal Plasma at 11–13 Weeks of Gestation

Abstract

Objective: To examine the feasibility of fetal RHD genotyping at 11–13 weeks’ gestation from analysis of circulating cell-free fetal DNA (ccffDNA) in the plasma of RhD negative pregnant women using a high-throughput robotic technique. Methods: Stored plasma (0.5 ml) from 591 RhD negative women was used for extraction of ccffDNA by a robotic technique. Real-time quantitative polymerase chain reaction (PCR) with probes for exons 5 and 7 of the RHD gene was then used to determine the fetal RHD genotype, which was compared to the neonatal RhD phenotype. Results: In total there were 502 (85.7%) cases with a conclusive result and 84 (14.3%) with an inconclusive result. The prenatal test predicted that the fetus was RhD positive in 332 cases and in all of these the prediction was correct, giving a positive predictive value of 100% (95% CI 96.8–100). The test predicted that the fetus was RhD negative in 170 cases and in 164 of these the prediction was correct, giving a negative predictive value for RhD positive fetuses of 96.5% (95% CI 93.7–99.2). Conclusion: The findings demonstrate the feasibility and accuracy of non-invasive fetal RHD genotyping at 11–13 weeks with a high-throughput technique.

Non-Invasive Prenatal <b><i>RHD</i></b> Genotyping Using Cell-Free Fetal DNA from Maternal Plasma: An Italian Experience

“…If we consider only studies which enrolled pregnant women at the 1st trimester of gestation [3,12,13,14,15], diagnostic accuracy in fetal RHD genotyping ranged from 91.1% to 100%. Our results fall within this range.…”

“…Many researchers have been focusing on the study and development of non-invasive diagnostic tests for RHD genotyping based on analysis of cell-free fetal DNA (cffDNA) from peripheral maternal blood and real-time PCR (qPCR) [2,3,4,5,6]. Although the most promising results were achieved when the test was performed during the 2nd and 3rd trimesters of pregnancy [7,8,9,10,11], a few approaches reached similar results in the 1st trimester [3,12,13,14,15]. …”

Avances en terapia fetal

“…[29][30][31] • Espectrofotometría del líquido amniótico (Delta O-450 en el gráfico de Liley) • Velocidad del pico sistólico de la arteria cerebral media (PS-ACM) • Cordocentesis: es el estándar de oro para evaluar el grado de anemia fetal.…”

Clinical Perspective of Cell-Free DNA Testing for Fetal Aneuploidies

“…The concept became possible after the discovery in 1997 that a high proportion of cfDNA fragments (around 150 kb each) in maternal plasma are of fetal origin [2]. The first clinical application of this discovery is in the non-invasive diagnosis of the fetal Rh blood type [3,4]. While the goal of assessing fetal aneuploidies in maternal blood was far more challenging, intensive research over recent years has led to the development of several solutions which are now commercially available.…”