Atypical presentation of familial hypomagnesemia with hypercalciuria and nephrocalcinosis in a patient with a new claudin-16 gene mutation.

Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is an autosomal recessive tubular disorder caused by mutations in genes that encode renal tight junction proteins claudin-16 or claudin-19, which are responsible for magnesium and calcium paracellular reabsorption in the thick ascending limb of Henle's loop. Progressive renal failure is frequently present, and most of the patients require renal replacement therapy still during adolescence. In this case report, we describe a new homozygous missense mutation on gene (c.