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Abstract: SA-PO1125

Crystal Conundrum: Renal Allograft Failure from Recurrent 2,8 Dihydroxyadenine Nephropathy

Session Information

Category: Trainee Case Report

  • 1902 Transplantation: Clinical

Authors

  • Nguyen, Kim Phung L., University of Texas Health Science Center at Houston, McGovern Medical School , Houston, Texas, United States
  • Edwards, Angelina, University of Texas at Houston Health Science Center, Houston, Texas, United States
  • Glass, William F., University of Texas – Houston Medical School, Houston, Texas, United States
  • Pai, Akshta, University of Texas Houston/McGovern Medical School, Houston, Texas, United States
  • De Golovine, Aleksandra, UTHSC-H, Houston, Texas, United States
Introduction

Post transplant crystalline nephropathy, a rare occurrence, can significantly impact allograft outcomes. Here we present a case of adenine phosphoribosyltransferase (APRT) deficiency resulting in excess adenine and consequentially insoluble 2,8-dihydroxyadenine (2,8-DHA) crystals leading allograft failure.

Case Description

A 68-yo man with ESRD presumably due to hypertension presented for deceased donor renal transplant. Pre transplant evaluation was unremarkable. Imaging of native kidneys revealed multiple cysts without stones. He received a 2A1B1DR HLA mismatch kidney, crossmatch negative, PRA 89%, blood group identical kidney from a hypertensive, diabetic deceased donor with KDPI of 75%. Patient received thymoglobulin induction followed by maintenance immunosuppression with prednisone, tacrolimus and mycophenolate mofetil. The surgical procedure was uneventful. A zero-hour biopsy showed donor-derived disease consisting of mild arteriosclerosis, 9% global glomerulosclerosis, 10% interstitial fibrosis. Postoperative allograft function was delayed. Hemodialysis (HD) was started on postop day (POD) 3. Renal ultrasound was unremarkable. Immunologic assessment with DSA was negative. On POD 14, transplant biopsy was performed showing acute tubular epithelium injury with numerous birefringent crystals initially interpreted as calcium oxalate crystals, suspicious for hyperoxaluric condition. Daily HD and supplementation with pyridoxine and calcium acetate were initiated. Renal function did not improve. Closer inspection of the biopsy with special stains revealed features of the crystals suspicious for 2,8-DHA nephropathy consistent with APRT deficiency. Patient was started on allopurinol, fluid infusion and low purine diet. HD was discontinued. Genetic testing revealed a homozygous pathogenic variant for the APRT sequence. Renal allograft function remained poor and progressed to primary nonfunction of the renal allograft.

Discussion

Although 2,8-DHA crystals, often misdiagnosed, resemble calcium oxalate crystals in being birefringent under cross-polarized light, crystals have a slightly yellow-brown coloration, and unlike oxalates, are argyrophilic with Jones silver stain. Timely diagnosis of 2,8-DHA nephropathy and aggressive management with xanthine dehydrogenase inhibitor and low purine diet may salvage the renal allograft.