Circulating nucleic acids in blood as biomarkers

This short review on a rapidly expanding domain in biomarkers focuses on the value of markers derived from either circulating intracellular DNA and RNA (leukocytes) or from free DNA and RNA in plasma or serum. In circulating intracellular DNA biomarkers, importance has been pointed to reside in the ever increasing number of SNPs directly related to disease such as hemochromatosis or associated with genetic make up that leads to different drug-susceptibility. Quantitative gene expression profiling, increasingly using global expression platforms, is gaining momentum in various disease states such as cancer, inflammation, cardiovascular disease and diabetes. Circulating free nucleic acids in plasma or serum gain in importance as biomarkers particularly in cancer and foeto-maternal understanding. The surprising recent findings of circulating free mRNA carries the potential of examining normal and diseased plasma for global gene expression profiling – opening avenues to new biomarkers. When appropriate, this review gives reference to methodological considerations and refers the readers to important literature in the fields