Observational Study Evaluating Serial T-ID Monitoring -ID-ENTITY

Inclusion Criteria: * Participants must meet all the following criteria: * Written informed consent and HIPAA authorization obtained prior to any study-related data collection. * Age ≥18 years at the time of enrollment. * Recipient of a kidney transplant, including: * Primary or repeat kidney transplantation * Living-donor or deceased-donor transplantation * At 1 month post-kidney transplant at the time of enrollment. * Receiving maintenance immunosuppressive therapy per institutional standard of care. * Selected by the treating provider to undergo TRAC testing as part of usual post-transplant clinical monitoring. Exclusion Criteria: * Recipient of a combined organ transplant involving a non-renal solid organ (e.g., kidney-liver, kidney-heart) and/or islet cell transplantation. * History of prior non-renal solid organ transplantation or islet cell transplantation. * Known pregnancy at the time of enrollment. * Known active viral infection at enrollment with any of the following: * Hepatitis B surface antigen (HBsAg)-positive * Hepatitis B virus (HBV) nucleic acid testing (NAT)-positive * Human immunodeficiency virus (HIV) infection or HIV NAT-positive * \*Known active BK virus-associated nephropathy (BKVAN) or CMV disease at the time of enrollment. * Medical, psychiatric, or social condition that, in the opinion of the Investigator, would interfere with the participant's ability to provide informed consent or comply with study procedures. * Concurrent participation in another investigational biomarker study designed to evaluate clinical utility of post-transplant molecular diagnostics. * Participants with asymptomatic or low-level viral replication detected during routine clinical monitoring are eligible, provided there is no evidence of established CMV disease or BK virus-associated nephropathy at enrollment.