A longitudinal study of urea cycle disorders
Mark L Batshaw, Mendel Tuchman, Marshall Summar, Jennifer Seminara, Members of the Urea Cycle Disorders Consortium, Mark L Batshaw, Mendel Tuchman, Marshall L Summar, Matthias R Baumgartner, Susan A Berry, Stephen Cederbaum, George A Diaz, Renata C Gallagher, Cary O Harding, George Hoffmann, Douglas S Kerr, Uta Lichter-Konecki, Shawn E McCandless, J Lawrence Merritt 2nd, Andreas Schulze, Margretta R Seashore, Tamar Stricker, Susan Waisbren, Derek Wong, Brendan Lee, Philippe Campeau, Peter J McGuire, Cynthia LeMons, Mary Lou Oster-Granite, Robert McCarter, Mark Yudkoff, Mark L Batshaw, Mendel Tuchman, Marshall Summar, Jennifer Seminara, Members of the Urea Cycle Disorders Consortium, Mark L Batshaw, Mendel Tuchman, Marshall L Summar, Matthias R Baumgartner, Susan A Berry, Stephen Cederbaum, George A Diaz, Renata C Gallagher, Cary O Harding, George Hoffmann, Douglas S Kerr, Uta Lichter-Konecki, Shawn E McCandless, J Lawrence Merritt 2nd, Andreas Schulze, Margretta R Seashore, Tamar Stricker, Susan Waisbren, Derek Wong, Brendan Lee, Philippe Campeau, Peter J McGuire, Cynthia LeMons, Mary Lou Oster-Granite, Robert McCarter, Mark Yudkoff
Abstract
The Urea Cycle Disorders Consortium (UCDC) is a member of the NIH funded Rare Diseases Clinical Research Network and is performing a longitudinal study of 8 urea cycle disorders (UCDs) with initial enrollment beginning in 2006. The consortium consists of 14 sites in the U.S., Canada and Europe. This report summarizes data mining studies of 614 patients with UCDs enrolled in the UCDC's longitudinal study protocol. The most common disorder is ornithine transcarbamylase deficiency, accounting for more than half of the participants. We calculated the overall prevalence of urea cycle disorders to be 1/35,000, with 2/3rds presenting initial symptoms after the newborn period. We found the mortality rate to be 24% in neonatal onset cases and 11% in late onset cases. The most common precipitant of clinical hyperammonemic episodes in the post-neonatal period was intercurrent infections. Elevations in both blood ammonia and glutamine appeared to be biomarkers for neurocognitive outcome. In terms of chronic treatment, low protein diet appeared to result in normal weight but decreased linear growth while N-scavenger therapy with phenylbutyrate resulted in low levels of branched chain amino acids. Finally, we found an unexpectedly high risk for hepatic dysfunction in patients with ornithine transcarbamylase deficiency. This natural history study illustrates how a collaborative study of a rare genetic disorder can result in an improved understanding of morbidity and disease outcome.
Keywords: Ammonia; Argininosuccinate lyase; Hyperammonemia; Longitudinal study; Ornithine transcarbamylase; Urea cycle.
Copyright © 2014 Elsevier Inc. All rights reserved.
Source: PubMed