Cell-free DNA-based FetoQuant Test A Noninvasive Prenatal Diagnosis of Fetal Trisomy 13 18 and 21 Using Next Generation Sequencing Technology

Non-invasive prenatal testing (NIPT) is frequently used for prenatal diagnosis of trisomies. Recent NIPT are mainly based on next-generation sequencing (NGS) technology. We aimed to develop a screening test for common aneuploidy using cell-free (cfDNA) from maternal blood using next generation sequencing (NGS).Material and method : The 779 blood samples of Iranian pregnant women at higher risk of trisomies used to evaluate the FetoQuant performance in detection of common trisomies 13, 18, and 21. NGS by the Ion ProtonTM platform was used to sequence the maternal cfDNA of plasma. Samples with fetal fraction ≥ 4 were included. Z-score was calculated and an algorithm was developed to determine the likelihood of trisomy, using DNA fragment counts. The results of FetoTest were verified by either amniocentesis or chorionic villus sampling (CVS). Beside the above mentioned samples, we included 5872 unknown pregnant sample who referred for NIPT analysis and pregnancy out comes has been followed.Result: Analysis of FetoTest performance at z-score ≥ 4 revealed that for trisomies 13, 18 and 21, sensitivity were 100%, 100% and 99.3%, specificity were, 99.98%, 99.97% and 99.77%, accuracy were, 99.98%, 99.97% and 99.77%, positive predictive value (PPV) were, 96.15%, 91.3% and 90.97% and negative predictive value (NPV) were, 100%, 100% and 99.98%, respectively.Conclusion: The data indicated that the FetoQuant test could be suggested as a robust non-invasive test for screening of fetal trisomies 13, 18, and 21 using maternal blood in early gestational weeks.