Clinical relevance of size selection of circulating DNA

Circulating cell-free DNA (cfDNA) is a non-invasive and powerful detection, diagnosis, prognosis, therapy response monitoring and recovery prediction tool, which opens new possibilities in fields of prenatal care, tumor therapy and transplant medicine. It is released from cells undergoing apoptosis and necrosis or by active secretion. Depending on the source and mechanisms of release, cfDNA is shed as fragments with different genetic and epigenetic profiles and in various lengths into the bloodstream. High- and low-weight cfDNA molecules can be detected in the different human body fluids. In pathological states, cfDNA size patterns have been found to vary from cfDNA released under healthy physiological conditions. In the following paragraphs, we describe methods and different technical platforms, to enrich, isolate and identify size profiles of cfDNA detected in human plasma and serum.