[Noninvasive prenatal diagnosis of trisomy 21, 18 and 13 using cell-free fetal DNA]

Trisomy 21, 18 and 13 are the most common trisomies diagnosed in newborns. Screening methods consist of ultrasound and maternal serum markers. High risk for fetal aneuploidies is an indication for routine karyotyping, which requires collection of fetal tissue through amniocentesis or chorionic villous sampling. They are invasive procedures and carry a potential risk of miscarriage. The discovery of cell free fetal DNA (cffDNA) in maternal blood offered new opportunities for noninvasive prenatal diagnosis. The fraction of cell-free fetal DNA in total pool of cell-free DNA in maternal plasma is very low, therefore the analysis of cffDNA is very challenging. The introduction of massive parallel sequencing has enabled the application of noninvasive prenatal testing in the clinical practice and a variety of recent studies have proven its high efficacy in diagnosing common aneuploidies.