CLDN1 and Hypercalciuria: Loss of Claudin 1 function mutations could result in neonatal ichthyosis-sclerosing cholangitis syndrome [16, 17], while the gene mutations in CLDN16 could cause familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) which is a rare autosomal recessive renal disease [18].