Hypercalciuria, or renal stone formation, is a genetically influenced common disorder. Using statistical pedigree analyses of 17 biochemical traits relevant to hypercalciuria, a number of traits with substantial genetic component (heritability) have been identified. The goal of this project is to use specific biochemical phenotypes to help localize genes involved in renal stone formation. In the past year the work on this project included preparation of the manuscript based on above noted pedigree analysis. Further work is ongoing in collaborating laboratories to complete data collection for statistical analysis of DNA polymorphisms using suggested heritable phenotypes, in order to localize DNA sequences relevant to formation of renal stones.