Circulating DNA, a Potentially Sensitive and Specific Diagnostic Tool for Future Medicine.

Liquid biopsy has the great potential of detecting early diseases before deterioration and is valued for screening abnormalities at early stage. In oncology, circulating DNA derived from shed cancer cells reflects the tissue of origin, so it could be used to locate tissue sites during early screening. However, the heterogenous parameters of different types limit the clinical application, making it inaccessible to encompass all the cancer types. Instead, for reproducible scenario as pregnancy, fetal cell-free DNA has been well utilized for screening aneuploidies. Noninvasive and convenient as is, it would be of great value in the next decades far more than early diagnosis. This review recapitulates the discovery and development of tumor and fetal cell-free DNA. The common factors are also present that could be taken into consideration when collecting, transporting, and preserving samples. Meanwhile, several protocols used for purifying cell-free DNA, either classic ones or through commercial kits, are compared carefully. In addition, the development of technologies for analyzing cell-free DNA have been summarized and discussed in detail, especially some up-to-date approaches. At the end, the potential prospect of circulating DNA is bravely depicted. In summary, although there would be a lot of efforts before it's prevalent, cell-free DNA remains a promising tool in point-of-care diagnostic medicine.