Cell-free DNA and RNA in plasma as new tools for molecular diagnostics.

The recent interest in plasma nucleic acids has opened up many new promising possibilities for the noninvasive detection and monitoring of a variety of diseases. The discovery of tumor-derived DNA in the plasma of cancer patients has provided an alternative method for cancer detection, monitoring and prognostication, whereas the presence of fetal DNA in maternal plasma has revealed significant clinical potential for the prenatal diagnosis of fetal genetic diseases and pregnancy-associated complications. Further applications have been reported in transplantation, traumatology and acute medicine. Extending beyond plasma DNA, a new field of investigation has also been developed in the analysis of plasma RNA, which holds promise for noninvasive gene expression profiling. Biologically, future work will focus on the elucidation of the origin and clearance of circulating DNA, as well as the unexpected stability of circulating RNA.