TY - JOUR T1 - Non-invasive prenatal testing: use of cell-free fetal DNA in Down syndrome screening JF - British Journal of General Practice JO - Br J Gen Pract SP - 298 LP - 299 DO - 10.3399/bjgp17X691625 VL - 67 IS - 660 AU - Imran Rafi AU - Melissa Hill AU - Judith Hayward AU - Lyn S Chitty Y1 - 2017/07/01 UR - http://bjgp.org/content/67/660/298.abstract N2 - Non-invasive prenatal testing (NIPT) is based on analysis of cell-free DNA (cfDNA) in maternal blood. The majority of cfDNA in maternal blood originates from the mother herself, with the fetal component (cffDNA) contributing approximately 10–20% of the total. cffDNA is present in maternal blood from early pregnancy.1 It emanates from the placenta, but represents the entire fetal genotype and is rapidly cleared from the maternal circulation with hours of delivery, making it pregnancy specific. If the fetus has Down syndrome (DS), there will be slightly more chromosome 21-specific DNA in the maternal circulation. With technological advances it has become possible to deliver highly accurate single-molecule counting and thereby detect small changes in the number of sequences on the chromosome of interest in blood.2 This approach forms the basis of NIPT for aneuploidy, a maternal blood test that can be performed in early pregnancy to significantly refine the DS risk, and reduce the need for invasive testing such as chorionic villus sampling (CVS) or amniocentesis.NIPT became available in Asia and the US in 2011 and, subsequent to significant commercial drive, is now available, largely in the private sector, throughout the world.3 NIPT has been widely validated, including comparison with standard prenatal aneuploidy screening,4 and has been shown to be a highly accurate screening test with high sensitivity (99%) and specificity (99.5%),5 which can be used from 10 weeks in pregnancy to determine risk of DS. NIPT can be used to screen for the other common chromosomal aneuploidies, trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome), albeit with … ER -