Donor APOL1 high-risk genotypes are associated with increased risk and inferior prognosis of de novo collapsing glomerulopathy in renal allografts

Collapsing focal segmental glomerulosclerosis (cFSGS) in the native kidney is associated with heavy proteinuria and accelerated renal failure. However, cFSGS in the renal allograft is less well characterized. Here we report clinicopathologic features and APOL1 donor risk genotypes in 38 patients with de novo post-kidney transplant cFSGS. Recipients were 34% female and 26% African American. Concurrent viral infections and acute vaso-occlusion (including thrombotic microangiopathy, cortical necrosis, atheroembolization, and cardiac arrest with contralateral graft thrombosis) were present in 13% and 29% of recipients, respectively. Notably, 61% of patients had concurrent acute rejection and 47% received grafts from African American donors, of which 53% carried APOL1 high-risk genotypes. These frequencies of acute rejection and grafts from African American donors were significantly higher than in our general transplant population (35% and 16%, respectively). Patients had a median serum creatinine of 5.4 mg/dl, urine protein/creatinine 3.5 g/g, and 18% had nephrotic syndrome. Graft failure occurred in 63% of patients at an average of eighteen months post-index biopsy. By univariate analysis, donor APOL1 high-risk genotypes, post-transplant time, nephrotic syndrome, and chronic histologic changes were associated with inferior graft survival while acute vaso-occlusion was associated with superior graft survival. Donor APOL1 high-risk genotypes independently predicted poor outcome. Compared to native kidney cFSGS, post-transplant cFSGS had more acute vaso-occlusion but less proteinuria. Thus, de novo cFSGS is associated with variable proteinuria and poor prognosis with potential predisposing factors of African American donor, acute rejection, viral infection and acute vaso- occlusion. Additionally, donor APOL1 high- risk genotypes are associated with higher incidence and worse graft survival.