Major research efforts in the last decade have been directed towards identifying novel mutations in FHHNC patients [7] and, as a result, 73 and 24 different mutations in CLDN16 and CLDN19, respectively, have been described and annotated in the Human Gene Mutation Database (HGMD) [8]. Here, CLDN16 is linked to familial primary hypomagnesemia with hypercalciuria and nephrocalcinosis.