This is an observational study to evaluate safety and efficacy outcomes in renal transplant recipients in whom post-transplant care is managed using AlloSure®. AlloSure® is a non-invasive test to measure donor-derived cell-free DNA (dd-cfDNA). The AlloSure test is intended to assess the probability of allograft rejection in kidney transplant recipients with clinical suspicion of rejection and to inform clinical decision-making regarding the necessity of renal biopsy in such patients at least 2 weeks post-transplant in conjunction with standard clinical assessment.

Amendment 1 (A1): Is an observational study to develop and validate the clinical use of KidneyCare®.

The AlloSure test has been approved for Medicare coverage for clinical use when a physician determines there is a need to assess the probability of allograft rejection in kidney transplant recipients. The DART study suggests that use of the non-invasive AlloSure test to measure donor-derived cell-free DNA (dd-cfDNA) can be used to discriminate active rejection in a renal transplant recipient. Use of the test may reduce invasive percutaneous renal biopsy procedures among patients with a suspicion of rejection.

Amendment 1 (A1) is intended to enable the development of KidneyCare® which is a panel test which includes the clinically validated commercial AlloSure dd-cfDNA test, combined with AlloMap Kidney which is a peripheral blood gene expression profiling test currently under development, and iBox, which is an analytic platform that predicts allograft survival at 3, 5, 7 and 10 years using a proprietary software algorithm based on a number of clinical inputs. The AlloMap Kidney and the iBox components are not yet clinically validated and so will not be used for patient management and are being developed through this study.

KOAR Inclusion Criteria:

1. Patient's health care provider adopts and intends to apply the center's AlloSure Routine Testing Schedule as part of the information used to manage the patient.
2. Subjects willing to provide written informed consent to participate.

KOAR Exclusion Criteria:

___________________________________________________________

Exclusions for AlloSure® Intended Use

Specimens from patients for whom any of the following are true will not be tested:

1. Recipients of transplanted organs other than kidney
2. Recipients of a transplant from a monozygotic (identical)
3. Recipients of a bone marrow transplant
4. Recipients who are pregnant
5. Recipients who are under the age of 18
6. Recipient who are less than 14 days post-transplant

All eligible renal transplant recipients who meet the inclusion/exclusion criteria will be a part of this observational study.

The control cohort will include the patients cared for without the use of AlloSure® or KidneyCare at the participating centers who received their transplant in the 6 months prior to the enrollment start for the primary cohort.