Kidney stone disease is a common and serious problem with increasing incidence and frequency across the world. Hypercalciuria is an independent risk factor for the most common type of kidney stones i.e. calcium oxalate and calcium phosphate stones. Annually, billions of dollars are spent on diagnosis and treatment. A gene-wide association study linked hypercalciuria and claudin-14 with kidney stones. For this project, we have two inter-related goals, to identify novel genetic causes of idiopathic hypercalciuria and to delineate the signaling pathway downstream of calcium sensing receptor (CaSR) activation mediating increased claudin-14 expression. For the first part of this project we have extracted DNA from blood samples of patients suffering from idiopathic hypercalciuria and sequenced a few candidate genes. We identified a SNP that was found with significantly increased frequency in our patients compared to the 5008-allele control data (NCBI). However, when functional studies were performed with this SNP no significant difference in expression was seen. Interestingly, while performing these studies another SNP in the claudin-14 gene was reported to associate with kidney stones. When we cloned this SNP into a reporter construct we found a significant increase in expression, (N.B. this is a reporter for claudin-14 expression) suggesting this is a disease-causing variation. The second part of this project is to delineate the CaSR signalling pathway leading to increased claudin-14 expression. For this we used a cell culture model and luciferase reporter assays. We found that two signalling molecules PKC and cdc42 are present downstream the CaSR activation leading to attenuation in the transcription factor SP1 expression which ultimate results in increased claudin-14 expression.