Down-regulation of magnesium transporting molecule, claudin-16, as a possible cause of hypermagnesiuria with the development of tubulo-interstitial nephropathy.
Mutations in two tight junction genes - claudin-16 and claudin-19 - cause the inherited renal disorder familial hypomagnesemia with hypercalciuria and nephrocalcinosis.
The patients' renal phenotype closely mimicked CLDN16-related nephropathy: low serum Mg2+ (<0.65 mmol/L) despite oral supplementation, hypercalciuria partly thiazide-sensitive, and progressive renal decline with ESRD reached at age 16 and 22 years in two individuals.