NIPS represents a major advance in screening for fetal chromosomal aneuploidies through the analysis of millions of cfDNA fragments in the blood of a pregnant woman. Chromosomal aneuploidies are characterized by an abnormal number of chromosomes, which may cause genetic disorders in a newborn baby, including some birth defects. Prenatal screening for chromosomal aneuploidies using analysis of serum proteins has been the standard of care for decades. However, cfDNA-based NIPS has become the preferred method of prenatal screening for many healthcare providers and patients since its introduction to clinical practice in 2011.
The high sensitivity and specificity, and low failure rate, of cfDNA-based NIPS result in fewer women undergoing invasive testing procedures. Although all positive prenatal screening results should be confirmed with diagnostic testing by chorionic villus sampling (CVS) or amniocentesis, cfDNA-based NIPS correctly identifies a higher proportion of pregnancies affected by chromosomal aneuploidies, including Trisomy 21/Down syndrome, Trisomy 18/Edwards syndrome, and Trisomy 13/Patau syndrome.
The Benefits of cfDNA-based NIPS
Extensive data have been published in peer-reviewed literature that establish the performance of cfDNA-based NIPS as a powerful screening tool for fetal chromosomal aneuploidies.1-5 In addition to having a significantly higher detection rate, cfDNA-based NIPS can simultaneously test for a larger number of specific chromosomal aneuploidies than traditional serum screening methods. Furthermore, the markedly lower false positive rates of cfDNA-based NIPS provide significantly improved positive predictive values compared to traditional screening tests.5 NIPS can be used as early as 9 to 10 weeks into the pregnancy.
Numerous professional organizations, including the American Congress of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine (SMFM), the International Society for Prenatal Diagnosis (ISPD), the American College of Medical Genetics and Genomics (ACMG), and the National Society of Genetic Counselors (NSGC) have recognized cfDNA-based NIPS as a screening option for all pregnancies, given appropriate patient counseling regarding the performance, risks and benefits of such testing.
- McCullough R. et al. (2014) Non-Invasive Prenatal Chromosomal Aneuploidy Testing - Clinical Experience: 100,000 Clinical Samples. PLoS ONE 9(10): e109173.
- Taneja, P. et al. (2016) Noninvasive prenatal testing in the general obstetric population: clinical performance and counseling considerations in over 85 000 cases . Prenatal Diagnosis 36(3), 237–243.
- Dar P. et al. (2014) Clinical experience and follow-up with large scale single-nucleotide polymorphism—based noninvasive prenatal aneuploidy testing. Am J Obstet Gynecol 211:527.e1-17.
- Mackie F. et al. (2016) The accuracy of cell-free fetal DNA-based non-invasive prenatal testing in singleton pregnancies: a systematic review and bivariate meta-analysis. BJOG DOI: 10.1111/1471-0528.14050.
- Norton M et al (2015) Cell-free DNA Analysis for Noninvasive Examination of Trisomy N Engl J Med 372:1589-97.