New screen on the block: non-invasive prenatal testing for fetal chromosomal abnormalities

Abstract

Non-invasive prenatal testing (NIPT) is a new screen for fetal chromosomal abnormalities. It is a screening test based on technology that involves the analysis of feto-placental DNA that is present in maternal blood. This DNA is then analysed for abnormalities of specific chromosomes (eg 13, 18, 21, X, Y). NIPT has a much higher screening capability for chromosomal abnormalities than current combined first trimester screening, with ~99% sensitivity for trisomy 21 (Down syndrome) and at least a 10-fold higher positive predictive value. The low false-positive rate (1-3%) is one of the most advertised advantages of NIPT. In practice, this could lead to a significant reduction in the number of false-positive tests and the need for invasive diagnostic procedures. NIPT is now suitable for singleton and twin pregnancies and can be performed from ~10 weeks in a pregnancy. NIPT is not currently publicly funded in most countries. However, the increasing availability of NIPT commercially will likely lead to an increase in demand for this as a screening option. Given the high numbers of women who visit a general practitioner (GP) in their first trimester, GPs are well-placed to also offer NIPT as a screening option. A GP's role in facilitating access to this service will likely be crucial in ensuring equity in access to this technology, and it is important to ensure that they are well supported to do so.

Noninvasive prenatal testing for chromosome aneuploidies and subchromosomal microdeletions/microduplications in a cohort of 8141 single pregnancies

“…In 1997, Lo et al reported that plasma from pregnant women carrying male fetuses contained cell-free DNA (cf-DNA) derived from the Y-chromosome [1]. Then, cell-free fetal DNA (cff-DNA) was subsequently reported to be used to detect fetal Down’s syndrome and additional fetal aneuploidies in clinical practice [2–4]. Now, noninvasive prenatal testing (NIPT) for fetal aneuploidies by scanning cell-free fetal DNA in maternal plasma is rapidly becoming a first-tier aneuploidy screening test in clinical practice [5, 6].…”

A retrospective study of noninvasive prenatal testing for chromosome aneuploidies and subchromosomal copy number variations in 24359 single pregnancies

“…The discovery of cell-free fetal DNA (cffDNA) in maternal plasma by Lo et al in 1997 has opened up new approaches for NIPT [1] . At present, NIPT has been gradually applied as a rst-tier aneuploidy screening strategy in clinical practice [2][3][4] . Previous large-scale clinical studies have revealed high accuracy of NIPT in screening on trisomy 21, 18 and 13, with sensitivity and speci city higher than 95% [5,6] , and the PPV range of trisomy 21 was 65-94%, trisomy 18 was 47-85%, and trisomy 13 was 12-62% [4,7,8] .…”

A Retrospective Study of Noninvasive Prenatal Testing for Chromosome Aneuploidies and Sub-Chromosomal Copy Number Variations in 24359 Single Pregnancies

“…The discovery of cell-free fetal DNA (cffDNA) in maternal plasma by Lo et al in 1997 has opened up new approaches for NIPT [1]. At present, NIPT has been gradually applied as a rst-tier aneuploidy screening strategy in clinical practice [2][3]. Previous large-scale clinical studies have revealed high accuracy of NIPT in screening on trisomy 21, 18 and 13, with sensitivity and speci city higher than 95% [4][5].…”