 During your study visit, we will draw one tube, about two teaspoonfuls 1 to 1 12 teaspoons for children, of blood from your arm to obtain white blood cells. These white blood cells will be used as a source of DNA for genetic testing. We will use the isolated DNA to try to identify the gene that is defective in Primary Hyperoxaluria by comparing it with the structure of genes in normal individuals, patients with Primary Hyperoxaluria, and family members of Primary Hyperoxaluria patients. In family members of primary hyperoxaluria patients, a 24 hour urine test may also be collected. 