title: Aneuploidy detection method based on cell-free DNA differential methylation between mother and fetus
design: Whole blood was centrifuged for 10 minutes at 1600g twice sequentially. After that plasma was separated and placed in new tubes, which were again centrifuged for 10 minutes at 1600g and then stored at 4˚C. Cell-free DNA was extracted from stored blood plasma using QIAamp DNA Circulating Nucleic Acid Kit (Qiagen) according to the manufacturer’s instructions. Extracted cfDNA underwent bisulphite conversion using Zymo Research EZ DNA Methylation Kit according to its protocol.