Advances in the medical research and clinical applications on the plasma DNA

Circulating DNA is free nucleic acids mainly present in the peripheral blood cells, synovial fluid and other body fluids. In the early 60s, there has been suggested that there may be free nucleic acid in the blood circulation, but it was not reported until 1977 by Leon et al. (1), with the finding to demonstrate that tumor derived DNA exists in the plasma of the patients with tumor and that the plasma DNA level in patients with cancer is significantly higher than that in the normal individual. In recent years, with the rapid advances in molecular biological technologies, the study on circulating DNA arouses attention dramatically. A new study using real-time PCR for the quantification of circulating DNA found that elevated levels of circulating DNA in patients with tumor are associated with disease characteristics and prognosis (2). This article reviews the advances in basic medical research and the clinical application of plasma DNA