Fetal DNA: strategies for optimal recovery.

For fetal DNA extraction, in principle each DNA extraction method can be used; however, because most methods have been optimized for genomic DNA from leucocytes, we describe here the methods that have been optimized for the extraction of fetal DNA from maternal plasma and validated for this purpose in our laboratories. The use of the QIAamp DSP Virus kit (QIAGEN), the QIAamp DNA Blood Mini kit (QIAGEN), and the Magna Pure LC (Roche) is based on the kit components provided by the respective companies. However, we noticed that the yield of fetal DNA from maternal plasma can be increased when higher volumes are processed or some slight modifications of the protocols provided by the manufacturer are followed. Here, we also describe an in-house method that allows the specific capture of target molecules in an extremely low volume by using magnetic beads and magnetic tips. This method can be either performed by hand, or it can be adapted to a commercially available pipetting workstation.