The goal of this observational study is to learn if the donor-derived cell-free DNA (dd-cfDNA) test can assess rejection in kidney transplant recipients. Participants will have blood and urine collected at their study visit.

Researchers will compare results of the GraftAssureDx to rejection detected by standard-of-care graft biopsies.

Inclusion Criteria:

1. Subject is 18 years of age or older
2. At least 12 calendar days have elapsed since the subject received a kidney transplant.
3. Subject has provided legally effective informed consent
4. Subject agrees to comply with all study procedures

Exclusion Criteria:

1. Kidney donor is an identical twin of the subject.
2. The subject has another previously transplanted organ in situ.
3. Subject has received a hematopoietic stem cell transplant.
4. Subject has received a bone marrow graft.
5. Subject has self-reported as pregnant.
6. In the opinion of the investigator, the subject's participation in the study would pose a risk to data integrity or to the subject's safety and welfare.

Sample Inclusion Criteria:

1. A graft biopsy is obtained within ±1 week of blood draw.

• If blood draw is obtained after biopsy, blood draw should be taken at least 2 days after an uncomplicated biopsy procedure.

Sample Exclusion Criteria:

1. Sample collected from someone that had an invasive graft biopsy ≤ 48 hours prior to blood draw.
2. Sample collected from subject that received immunosuppressive treatment for biopsy-proven acute rejection ≤ 30 days prior to blood draw
3. Sample collected from subject that received a blood transfusion ≤ 30 days prior to blood draw.
4. Sample collected from a subject that provided another sample for the study within the past 7 days.

Individuals who have received a kidney transplant at centers in the United States and Germany will be invited to participate.

only IPD used in the results publication