How to analyze the DNA from a pregnant woman.

摘要

Blood plasma of a pregnant woman contains both fetal and maternal circulatory extracellular DNA, the latter forming the major part (generally 90%) thereof. The majority of the circulatory extracellular fetal DNA has now been found to have a small size of approximately 500 base pairs or less whereas the majority of the circulatory extracellular maternal DNA has a size greater than approximately 500 base pairs. Separation of circulatory extracellular DNA fragments which are smaller than approximately 500 base pairs provides a possibility to enrich for fetal DNA sequences from the vast bulk of circulatory extracellular maternal DNA. ??There is thus provided a sample of the blood plasma or serum (which preferably is substantially cell-free) of a pregnant woman in which extracellular DNA comprising 500 base pairs or less is enriched; the manufacture of such sample by subjecting a sample of the blood plasma or serum of a pregnant woman to a size separation so as to enrich extracellular DNA comprising 500 base pairs or less; and the use of such sample for the non-invasive detection of fetal genetic traits.