Novel pathogenic variant causing familial hypomagnesemia with hypercalciuria and nephrocalcinosis

Abstract

Nephrocalcinosis in children can arise due to a variety of metabolic conditions and appropriate diagnosis can lead to specific management and has implications in prognosis. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is a rare disease with varied manifestations which is caused by mutations in CLDN16 and CLDN19, and has a high rate of progression to kidney failure in the second to third decades of life. Early diagnosis aids in retardation of the progression to kidney failure. We present two unrelated patients presenting with nephrocalcinosis and deranged renal function, who had a novel pathogenic variation (c.685C > T; p.Q229X), leading to the diagnosis of FHHNC. Genetic testing is crucial in patients presenting with nephrocalcinosis for diagnosis and prognostication.