CLDN14 encodes claudin 14, a tight junction protein that plays a critical role in regulating paracellular permeability in epithelial cells, particularly in the kidney and inner ear 1. The protein functions as a key component of tight junctions, facilitating calcium-independent cell-cell adhesion and controlling the differential handling of divalent cations like magnesium and calcium 2. In the kidney, claudin 14 is expressed in distal nephron segments and its expression is regulated by dietary magnesium content, influencing the paracellular transport of Mg2+ and Ca2+ 2. CLDN14 mutations are associated with autosomal recessive non-syndromic hearing loss (DFNB29), with various pathogenic variants identified in affected families 34. Additionally, common variants in CLDN14 are strongly associated with kidney stone formation, with approximately 62% of the population carrying risk alleles that confer 1.64 times greater disease risk 1. These same variants also associate with reduced bone mineral density, suggesting broader effects on calcium homeostasis 1. The gene's role in Meniere's disease has also been reported, further highlighting its importance in inner ear function 5. CLDN14 represents a clinically significant gene linking tight junction function to both renal stone disease and hereditary deafness.