During your study visit, we will draw one tube, about two teaspoons (1 to 1 ½ teaspoons for children), of blood from your arm. White blood cells from the sample will be used as a source of DNA for genetic testing. We will use the DNA to try to identify mutations (changes) in one of the genes that can cause primary hyperoxaluria. This will be done by comparing it with the structure of these genes in normal individuals, patients with primary hyperoxaluria, and family members of primary hyperoxaluria patients. In family members of primary hyperoxaluria patients, a 24 hr urine test may also be collected.