Non-invasive prenatal testing - new possibilities on the horizon and old problems

Non-invasive prenatal testing (NIPT) is a screening method that accesses placenta-derived DNA. Contrary to its name, no foetal DNA is tested here, despite the fact that it is often referred to as a test of 'free foetal DNA'. NIPT is available in at least five different technical variants and can test for aneuploidies of chromosomes 13, 18 and 21, with or without testing the sex chromosomes. It can also test all chromosomes for aneuploidy, although polyploidy is only accessible with a single nucleotide polymorphism (SNP)-based test system. It can also check for targeted microdeletion/microduplication syndrome critical regions. Among others, as NIPT uses placental DNA, a certain rate of false-positive and false-negative results is to be expected in the case of copy number variation detection. For some years now, existing commercial NIPT variants have been expanded to include single-gene-mutation-oriented testing. Here, foeto-placental divergence seems to play a minor role, while distinguishing maternal and placenta-derived cell-free DNA remains challenging. This article reviews the milestones of NIPT and its current developments, focusing on the challenges of incorporating this approach into existing prenatal care schemes and the situation in Germany.