Donor-derived cell-free DNA (dd-cfDNA) has been proposed as a potential diagnostic tool to monitor the rejection status of the kidney transplant. It has been suggested that dd-cfDNA is increasing in the blood of kidney transplant patient presenting a graft rejection. In this project, investigators proposed a different approach to predict and characterize kidney transplant rejection/dysfunction based on the quantification of epigenetic signatures present on the donor-cell-free DNA. In 2018, Moss et al. develops a deconvolution model capable of identifying the tissue origin of circulating DNA by taking advantage of its epigenetic properties. The study confirmed that the cell-free DNA circulating in healthy subjects comes mainly from blood cells and endothelial cells, but not from kidney cells. In this study, researchers investigate the evolution of blood renal-specific cell-free DNA amount in patient with chronic kidney disease before and after the transplantation surgery by testing a set of renal-specific epigenetic markers. The purpose of this study is to identify the biological noise of native kidney on renal-specific cell-free DNA and to compare it with signal coming from transplanted kidney.