Utility of Genetic Analysis in Rare Tubulopathies Presenting with Bilateral Nephrocalcinosis in Adults - Avoiding Harm with Precision Care: A Case Series

Two rare cases of nephrocalcinosis (NC) due to a genetic mutation remained undiagnosed till adulthood. A 19-year-old male presented with a fever and was diagnosed with bilateral NC and renal dysfunction. He underwent a renal biopsy, which suggested nonspecific chronic tubulointerstitial nephritis. His blood chemistry review showed persistent severe hypouricemia, pointing to possible xanthinuria. The second case was a 25-year-old male, re-evaluated for bilateral NC with persistently high serum parathyroid hormone despite successful parathyroidectomy. His metabolic workup suggested possible Bartter’s syndrome (BS) with characteristic biochemical derangement. Whole exome sequencing detected a pathogenic homozygous mutation in the MOCOS gene in the first case and a KCNJ1 mutation in the second case. Soft clues like hypouricemia in the first and hypokalemia with metabolic alkalosis in the second case need to be recognized in NC for the appropriate work-up. Tailored management has stabilized the renal outcome in both patients.