ENRICHMENT OF SMALL NUCLEIC ACIDS

摘要

Provided herein is technology related to processing samples of nucleic acids and particularly, but not exclusively, to methods for enriching samples for small nucleic acids, such as small circulating cell-free DNA. Apoptotic fetal trophoblasts shed cffDNA directly into maternal blood in the placenta during gestation. It is estimated that cffDNAs are liberated into maternal plasma at a rate of approximately 20,000 per minute in 2.5 liters of maternal plasma (approximate total blood volume of a typical female is 5 liters) and are detected by some tests in circulating maternal plasma by approximately the 10th or 11th week of gestation and, in some studies, as early as the 5th week (see, e.g., Holmberg et al (2013), PLoS One 8(8):e73068) or, by some tests, as early as the 18th day of gestation (see, e.g., Guibert et al (2003) Hum Reprod 18:1733-6). A quasi-steady state relationship exists between cffDNA biogenesis in maternal plasma and cffDNA degradation by maternal plasma nucleases.