 This is a prospective, multicenter, observational study of kidney transplant subjects where blood specimens, intended for dd-cfDNA and other future research purposes, will be drawn after transplant periodically and also after the treatment of acute rejection up to 8 weeks post treatment. The blood samples and all relevant clinical data will be provided to CareDx scientists for laboratory assay of dd-cfDNA levels and correlation of dd-cfDNA levels with the clinical features of the subjects. 