Non-invasive prenatal test using cell free DNA

Although conventional prenatal screening tests for Down syndrome have been developed over the past 20 years, the positive predictive value of these tests is around 5%. Through these tests, many pregnant women have taken invasive tests including chorionic villi sampling and amniocentesis for confirming Down syndrome. Invasive test carries the risk of fetal loss at a low but significant rate. There is a large amount of evidence that non-invasive prenatal test (NIPT) using cell free DNA in maternal serum is more sensitive and specific than conventional maternal serum and/or ultrasound screening. Therefore implementing NIPT will increase aneuploidy detection rate and concurrently decrease fetal loss rate accompanying invasive test. More than 1,000,000 NIPT were performed globally since 2011. The uptake rate of NIPT is expected to increase more rapidly in the future. Moreover, as a molecular genetic technique advances, NIPT can be used for not only common aneuploidy screening but single gene disorder, microdeletion, and whole fetal genome sequencing. In this review, I will focus on the NIPT for common aneuploidies such as trisomy 13, 18, and 21.