DNA Extraction from Various Types of Prenatal Specimens

A prenatal noninvasive genetic screening test that yields a positive result typically warrants further direct assessment of fetal DNA following an invasive procedure. The precious nature of these invasively acquired samples, combined with the time sensitive nature with which results should be reported, demands that the methodologies used for analysis be quick, efficient, and dependable.Prenatal diagnosis has been performed using DNA extracted from amniotic fluid and chorionic villi for several decades, and more recently methodologies have been developed to extract cell free fetal DNA from amniotic fluid. DNA extraction methodologies in these matrices should reliably and reproducibly isolate a sufficient quality and quantity of DNA for the intended downstream application, and make it possible to purify and concentrate samples that may arrive with suboptimal quality or quantity.Phenol-Chloroform extraction followed by DNA precipitation in ethanol has historically been used for prenatal samples, but this methodology is labor intensive, time consuming, and requires use of toxic chemicals. There are now commercially available, solid phase-based kits for rapid and reproducible DNA extraction and purification, enabling simultaneous extraction of a large number of samples. Commercial kits are available for a variety of sample matrices including all prenatal specimen types, although other methodologies including organic or inorganic liquid phase extraction may also be utilized.Here, we describe extraction using both commercially available kits for direct amniocytes and chorionic villi and cell free fetal DNA derived from amniotic fluid, as well as inorganic liquid phase extraction for tissue culture of amniocytes, CVS, and products of conception.