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Kidney Week

Abstract: PO2204

2,8-Dihydroxyadenine Crystalline Nephropathy in Transplanted Kidney

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Raza, Hafiz Muhammad Ali, The University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Nieves, Genesis, The University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Bhalla, Anshul, The University of Tennessee Health Science Center, Memphis, Tennessee, United States
  • Wall, Barry M., The University of Tennessee Health Science Center, Memphis, Tennessee, United States
Introduction

2,8-dihydroxyadeninuria (DHA) disease is a rare autosomal recessive disorder caused by adenine phosphoribosyltransferase (APRT) deficiency, that typically manifests with nephrolithiasis, but rarely can cause chronic kidney disease (CKD). Recurrence of DHA nephropathy after kidney transplant can cause persistent allograft dysfunction with increased risk of early graft failure if diagnosis and treatment are delayed. We describe a case of APRT deficiency which remained undiagnosed until evaluation of a poorly functioning kidney allograft due to DHA nephropathy, successfully managed with allopurinol and conversion to Belatacept.

Case Description

72-year-old Caucasian male with ESRD secondary to diabetes mellitus type 2 and obstructive uropathy. The patient received a living donor kidney transplant from his daughter on 10/15/2020 with Thymoglobulin and steroid induction followed by maintenance immunosuppression with tacrolimus, mycophenylate, and prednisone. It was a one haplotype mismatch with no pre-formed donor specific antibodies. He had slow graft function with a creatinine of 4 mg/dL on discharge.

At 6 weeks post-transplant, his creatinine remained elevated at 2.1 - 2.3 mg/dl with no clear cause for persistent allograft dysfunction. An allograft renal biopsy showed numerous polarizable pigmented brown intratubular crystals, in the absence of triamterene-based diuretics. A diagnosis of 2,8 DHA crystalline nephropathy was made and he was started on allopurinol and a low purine diet. To minimize tubular injury, Belatacept was added to maintenance immunosuppression and tacrolimus dose was reduced with a goal to wean over 9 months. To further confirm the diagnosis, a kidney gene panel was performed confirming homozygous ARPT deficiency with an autosomal recessive inheritance pattern. Kidney function continued to improve with creatinine of 1.5 mg/dl (eGFR 45 ml/min/1.73m2) at 7 months post-transplant.

Discussion

DHA nephropathy due to APRT deficiency is a rare but preventable cause of CKD and can remain undiagnosed until its recurrence after kidney transplant. To prevent allograft failure, high index of suspicion and early biopsy is important. In addition to allopurinol, low purine diet, and increased hydration, CNI minimization and utilization of Belatacept is an effective strategy to minimize vascular and tubular injury and prevent further precipitation of crystals.