Clinical perspective of cell-free DNA testing for fetal aneuploidies.

Cell-free DNA testing in maternal blood provides the most effective method of screening for trisomy 21, with a reported detection rate of 99% and a false positive rate of less than 0.1%. After many years of research, this method is now commercially available and is carried out in an increasing number of patients, and there is an expanding number of conditions that can be screened for. However, the application of these methods in clinical practice requires a careful analysis. Current first-trimester screening strategies are based on a complex combination of tests, aiming at detecting fetal defects and predicting the risk of main pregnancy complications. It is therefore necessary to define the optimal way of combining cell-free DNA testing with current first-trimester screening methods. In this concise review we describe the basis of cell-free DNA testing and discuss the potential approaches for its implementation in combination with current tests in the first trimester.