Size-selective separation and overall-amplification of cell-free fetal DNA fragments using PCR-based enrichment.

This study aimed to establish a method for the selective amplification of cell-free fetal DNA (cffDNA) in maternal plasma and preserve the integrity of DNA fragments during amplification, thereby providing a sufficient amount of cffDNA to meet the requirement of routine non-invasive prenatal testing. We amplified DNA molecules in a one-reaction system without considering their particular sequences and lengths (overall amplification) by using PCR-based enrichment. We then modified PCR conditions to verify the effect of denaturation temperature on DNA amplification on various lengths of DNA (selective overall amplification). Finally, we used an optimum temperature range to amplify cffDNA selectively. Amplification results were validated by electrophoresis and real-time quantitative PCR. Our PCR-based enrichment efficiently amplified all DNA fragments with differing lengths within a single reaction system, as well as preserving the integrity of the DNA fragments. cffDNA was significantly amplified along with the selective amplification of small fragment maternal plasma DNA in an appropriate range of denaturation temperatures. We have established a PCR-based method for the simultaneous enrichment and amplification of cffDNA in order to meet the requirements of high cffDNA quantity for routine non-invasive prenatal testing.