Recurrent urinary tract infection and nephrocalcinosis: Answers

Both siblings presented with early onset of recurrent UTI, nephrocalcinosis, hypercalciuria, hypocitraturia, and hypomagnesemia. Hyperuricemia and secondary hyperparathyroidism are likely due to the lower estimated kidney function using the cystatin-C and creatinine equations. Their clinical signs and symptoms can be associated with medullary cystic disease or autosomal dominant tubulointerstitial disease, Dent disease although this predominantly affects male, hyperoxaluria or familial hypomagnesemia, hypercalciuria, and nephrocalcinosis (FHHNC, OMIM #248190). Genetic testing was obtained in Patient A which showed homozygous mutation in CLDN19 gene, c.59G>A p. Gly20Asp, compatible with the diagnosis of FHHNC with ocular involvement (FHHNCOI). Subsequently, Patient B was tested and showed the same homozygous mutation as his sister but he had no ocular abnormality.