PROJECT SUMMARY/ABSTRACT Recipients of a kidney transplant from an African-American deceased donor have worse outcomes than their counterparts receiving an organ from a European-American deceased donor. In addition, kidney transplants from deceased donors with two apolipoprotein L1 gene (APOL1) high-risk genotypes, which is almost exclusively found in individuals of recent African ancestry, have shorter survival. Some recipients of these organs, however, have good long-term outcomes. Therefore, we hypothesize that APOL1 genes interact with other environmental or inherited factors to cause accelerated failure of kidney transplants. Similarly, living donors of recent African ancestry face increased risk of post-donation kidney failure compared to European-American living donors, but the potential impact of APOL1 genotypes in these donors is unclear. The National Institutes of Health (NIH) established the “APOL1 Long-term Kidney Transplantation Outcomes” (APOLLO) U01 Consortium in 2017 to prospectively address several questions regarding APOL1 genotyping in kidney transplantation. The APOLLO Consortium includes a Scientific and Data Research Center and 13 Clinical Centers, including our University of Wisconsin Clinical Center. In the proposed APOLLO Phase 2, we will collect extended long-term data on graft function, injury, and survival to more comprehensively define outcomes associated with donor and recipient APOL1 genetic variants and continue to recruit new living donors of African ancestry. Working with the SDRC, we will return APOL1 genotype results to enrolled transplant recipients and living donors. The data to be collected will define the impact of genotypes on graft outcomes and living donors and identify secondary factors that modify outcomes. These data are critical to improve allograft survival and quality of life for all transplant recipients.