It has been shown that the amount of circulating donor-cell-free DNA increases in patients with transplant rejection. Quantification of single nucleotide polymorphisms (SNPs) present in circulating donor DNA currently allows for early identification of transplant rejection, but not for characterization, i.e., identification of the affected renal fraction of the graft. Recently, in healthy subjects, teams have shown that it is possible to identify the tissue origin of donor-cell-free DNA, based on the epigenetic properties of circulating DNA. CGenetix is a MedTech company developing an in vitro diagnostic medical device to identify and quantify kidney graft degradation during transplant rejection. The objective of this study is to evaluate the sensitivity of the proposed technology to detect circulating renal DNA released into the blood and urine in kidney transplant patients with or without graft rejection.