Cell-free DNA Analysis for Noninvasive Examination of Trisomy

This multicenter study compared a prenatal assay of cell-free DNA with a standard method of screening for trisomies among women at average risk. The positive predictive values of cfDNA testing and standard screening for trisomy 21 were 80.9% and 3.4%, respectively. Screening for fetal aneuploidy with the use of cell-free DNA (cfDNA) obtained from maternal plasma was introduced in 2011. Such screening has been reported to have a detection rate for trisomy 21 (Down's syndrome) of more than 99%, with a false positive rate as low as 0.1%. 1 Thus, cfDNA testing appears to represent a substantial improvement over traditional multiple-marker screening. In practice, the use of this test could result in a significant reduction in diagnostic procedures. Although several large proof-of-principle studies have confirmed the high sensitivity and specificity of cfDNA testing for the detection of trisomy 21, most of these . . .