Renal Transplantation in Rare Monogenic Urinary Stone Disease - A Single-center Experience

Introduction:Monogenic urinary stone disease (MUSD) tends to be more severe with early onset of symptoms and a higher risk of chronic kidney disease than sporadic USD. The literature on the outcome after renal transplant in patients with certain MUSD is scarce.Materials and Methods:This is a retrospective single-center observational study conducted in a tertiary care renal transplant unit in North India between 2018 and 2021. The renal transplant recipients who developed an end-stage renal disease (ESRD) due to renal calculus disease/nephrocalcinosis were included in the study. All the patients presented to us in an anuric state, and hence, a 24-h urine metabolic profile could not be performed. Ear, nose, and throat and ophthalmological evaluations were done to rule out extrarenal manifestations. These patients were subjected to genetic analysis, i.e., clinical exome sequencing using next-generation sequencing.Results:Out of 283 live renal transplants, 11 patients developed ESRD due to nephrocalcinosis/renal calculus disease. Out of 11, only 4 had genetic mutations and the rest did not have any identifiable genetic mutations. The gene mutations were identified in ADCY10, CLDN16, CaSR, and SLC3A4. The patient with ADCY10 mutation had a strong family history. The clinical phenotype and in silico parameters analysis predicted the variant to be damaging except the one with CaSR mutation which causes Hypocalciuric hypercalcemia syndrome, type 1. Three of four underwent surgical intervention at younger age. All underwent successful live-related renal transplantation, with good graft function on follow-up, without any recurrence of calculus in the allograft.Conclusion:Renal transplantation can be safely proceeded in patients with the above monogenic mutations. Genetic analysis should be a part of pretransplant evaluation in young onset nephrolithiasis and end-stage kidney disease patients to look for a monogenic cause, to assess the risk of recurrence postrenal transplant.