Genetic Heritability of Urinary Stone Risk in Identical Twins

No AccessJournal of UrologyAdult urology1 Jun 2006Genetic Heritability of Urinary Stone Risk in Identical Twins Manoj Monga, Brandon Macias, Eli Groppo, and Alan Hargens Manoj MongaManoj Monga Department of Urologic Surgery, University of Minnesota, Minneapolis, Minnesota , Brandon MaciasBrandon Macias Department of Orthopaedic Surgery, University of California-San Diego, San Diego, California , Eli GroppoEli Groppo Department of Orthopaedic Surgery, University of California-San Diego, San Diego, California , and Alan HargensAlan Hargens Department of Orthopaedic Surgery, University of California-San Diego, San Diego, California View All Author Informationhttps://doi.org/10.1016/S0022-5347(06)00272-2AboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract Purpose: Quantitative measurements of urinary parameters are valuable clinical tools for predicting the risk of nephrolithiasis. To our knowledge no previous studies have evaluated the heritability of urinary stone risk in identical twins. Because these individuals share identical genetics, the R defined by their phenotypic data are theoretically equal to the entire population H2. Materials and Methods: A total of 12 sets of healthy homozygous twins, including 4 males and 8 females for a total of 24 individuals, with a mean age of 25.9 years (range 21 to 36) volunteered for this study. All subjects provided informed written consent before assessment. Urinary stone risk profiles were done elsewhere on 2 consecutive days after 5 days of a standardized diet (170 mEq Na and 2500 kcal). Linear regression was performed on the data to determine R. Because identical twins were used, R was theoretically an estimate of H2. Results: Certain urinary stone risk markers were highly heritable, including urinary calcium (94%), oxalate (94%), citrate (95%), uric acid (96%) and brushite supersaturation (90%), as determined by genotype (H2 90% or greater). Uric acid supersaturation (58%) and urinary sodium (64%) had low degrees of heritability. Conclusions: H2 is a measure of how much of the total variance in phenotype results from differences in genotype, as opposed to environmental differences. For example, an H2 of 95% for citrate suggests that genetic differences account for 95% of the variation in urinary citrate and environmental differences account for the remaining 5%. Therefore urinary calcium, oxalate and citrate are primarily determined by genotype, while environmental factors, particularly those that impact urine pH and urinary volume, may be increasingly important for determining uric acid supersaturation. References 1 : Family history of renal stones in recurrent stone patients. 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Google Scholar © 2006 by American Urological AssociationFiguresReferencesRelatedDetails Volume 175Issue 6June 2006Page: 2125-2128 Advertisement Copyright & Permissions© 2006 by American Urological AssociationKeywordsgeneticstwinsurinary calculiAcknowledgmentsThe 24-hour stone risk profiles were done at Mission Pharmacal, San Antonio, Texas.MetricsAuthor Information Manoj Monga Department of Urologic Surgery, University of Minnesota, Minneapolis, Minnesota Financial interest and/or other relationship with Bard, Cook, Microvasive, Applied, Storz, Wolf, ACMI, Stryker, Olympus, Boehringer, Merck and Pfizer. More articles by this author Brandon Macias Department of Orthopaedic Surgery, University of California-San Diego, San Diego, California More articles by this author Eli Groppo Department of Orthopaedic Surgery, University of California-San Diego, San Diego, California More articles by this author Alan Hargens Department of Orthopaedic Surgery, University of California-San Diego, San Diego, California More articles by this author Expand All Advertisement PDF downloadLoading ...