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Häberle J, Boddaert N, Burlina A, Chakrapani A, Dixon M, Huemer M, Karall D, Martinelli D, Crespo PS, Santer R, Servais A, Valayannopoulos V, Lindner M, Rubio V, Dionisi-Vici C. Suggested guidelines for the diagnosis and management of urea cycle disorders. Orphanet J Rare Dis 2012; 7:32. [PMID: 22642880 PMCID: PMC3488504 DOI: 10.1186/1750-1172-7-32] [Citation(s) in RCA: 362] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 04/06/2012] [Indexed: 12/11/2022] Open
Abstract
Urea cycle disorders (UCDs) are inborn errors of ammonia detoxification/arginine synthesis due to defects affecting the catalysts of the Krebs-Henseleit cycle (five core enzymes, one activating enzyme and one mitochondrial ornithine/citrulline antiporter) with an estimated incidence of 1:8.000. Patients present with hyperammonemia either shortly after birth (~50%) or, later at any age, leading to death or to severe neurological handicap in many survivors. Despite the existence of effective therapy with alternative pathway therapy and liver transplantation, outcomes remain poor. This may be related to underrecognition and delayed diagnosis due to the nonspecific clinical presentation and insufficient awareness of health care professionals because of disease rarity. These guidelines aim at providing a trans-European consensus to: guide practitioners, set standards of care and help awareness campaigns. To achieve these goals, the guidelines were developed using a Delphi methodology, by having professionals on UCDs across seven European countries to gather all the existing evidence, score it according to the SIGN evidence level system and draw a series of statements supported by an associated level of evidence. The guidelines were revised by external specialist consultants, unrelated authorities in the field of UCDs and practicing pediatricians in training. Although the evidence degree did hardly ever exceed level C (evidence from non-analytical studies like case reports and series), it was sufficient to guide practice on both acute and chronic presentations, address diagnosis, management, monitoring, outcomes, and psychosocial and ethical issues. Also, it identified knowledge voids that must be filled by future research. We believe these guidelines will help to: harmonise practice, set common standards and spread good practices with a positive impact on the outcomes of UCD patients.
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Affiliation(s)
- Johannes Häberle
- University Children’s Hospital Zurich and Children’s Research Centre, Zurich, 8032, Switzerland
| | - Nathalie Boddaert
- Radiologie Hopital Necker, Service Radiologie Pediatrique, 149 Rue De Sevres, Paris 15, 75015, France
| | - Alberto Burlina
- Department of Pediatrics, Division of Inborn Metabolic Disease, University Hospital Padua, Via Giustiniani 3, Padova, 35128, Italy
| | - Anupam Chakrapani
- Birmingham Children’s Hospital NHS Foundation Trust, Steelhouse Lane, Birmingham, B4 6NH, United Kingdom
| | - Marjorie Dixon
- Dietetic Department, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, WC1N 3JH, United Kingdom
| | - Martina Huemer
- Kinderabteilung, LKH Bregenz, Carl-Pedenz-Strasse 2, Bregenz, A-6900, Austria
| | - Daniela Karall
- University Children’s Hospital, Medical University Innsbruck, Anichstrasse 35, Innsbruck, 6020, Austria
| | - Diego Martinelli
- Division of Metabolism, Bambino Gesù Children’s Hospital, IRCCS, Piazza S. Onofrio 4, Rome, I-00165, Italy
| | | | - René Santer
- Universitätsklinikum Hamburg Eppendorf, Klinik für Kinder- und Jugendmedizin, Martinistr. 52, Hamburg, 20246, Germany
| | - Aude Servais
- Service de Néphrologie et maladies métaboliques adulte Hôpital Necker 149, rue de Sèvres, Paris, 75015, France
| | - Vassili Valayannopoulos
- Reference Center for Inherited Metabolic Disorders (MaMEA), Hopital Necker-Enfants Malades, 149 Rue de Sevres, Paris, 75015, France
| | - Martin Lindner
- University Children’s Hospital, Im Neuenheimer Feld 430, Heidelberg, 69120, Germany
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas (IBV-CSIC) and Centro de Investigación Biomédica en Red para Enfermedades Raras (CIBERER), C/ Jaume Roig 11, Valencia, 46010, Spain
| | - Carlo Dionisi-Vici
- Division of Metabolism, Bambino Gesù Children’s Hospital, IRCCS, Piazza S. Onofrio 4, Rome, I-00165, Italy
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102
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Bireley WR, Van Hove JLK, Gallagher RC, Fenton LZ. Urea cycle disorders: brain MRI and neurological outcome. Pediatr Radiol 2012; 42:455-62. [PMID: 21989980 DOI: 10.1007/s00247-011-2253-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 08/17/2011] [Accepted: 08/22/2011] [Indexed: 01/09/2023]
Abstract
BACKGROUND Urea cycle disorders encompass several enzyme deficiencies that can result in cerebral damage, with a wide clinical spectrum from asymptomatic to severe. OBJECTIVE The goal of this study was to correlate brain MRI abnormalities in urea cycle disorders with clinical neurological sequelae to evaluate whether MRI abnormalities can assist in guiding difficult treatment decisions. MATERIALS AND METHODS We performed a retrospective chart review of patients with urea cycle disorders and symptomatic hyperammonemia. Brain MRI images were reviewed for abnormalities that correlated with severity of clinical neurological sequelae. RESULTS Our case series comprises six urea cycle disorder patients, five with ornithine transcarbamylase deficiency and one with citrullinemia type 1. The observed trend in distribution of brain MRI abnormalities as the severity of neurological sequelae increased was the peri-insular region first, extending into the frontal, parietal, temporal and, finally, the occipital lobes. There was thalamic restricted diffusion in three children with prolonged hyperammonemia. Prior to death, this site is typically reported to be spared in urea cycle disorders. CONCLUSION The pattern and extent of brain MRI abnormalities correlate with clinical neurological outcome in our case series. This suggests that brain MRI abnormalities may assist in determining prognosis and helping clinicians with subsequent treatment decisions.
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Affiliation(s)
- William R Bireley
- Department of Radiology, University of Colorado, 12631 E. 17th Ave., Aurora, CO 80045, USA.
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103
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Wang L, Morizono H, Lin J, Bell P, Jones D, McMenamin D, Yu H, Batshaw ML, Wilson JM. Preclinical evaluation of a clinical candidate AAV8 vector for ornithine transcarbamylase (OTC) deficiency reveals functional enzyme from each persisting vector genome. Mol Genet Metab 2012; 105:203-11. [PMID: 22133298 PMCID: PMC3270700 DOI: 10.1016/j.ymgme.2011.10.020] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 10/31/2011] [Accepted: 10/31/2011] [Indexed: 10/15/2022]
Abstract
Ornithine transcarbamylase deficiency (OTCD), the most common and severe urea cycle disorder, is an excellent model for developing liver-directed gene therapy. No curative therapy exists except for liver transplantation which is limited by available donors and carries significant risk of mortality and morbidity. Adeno-associated virus 8 (AAV8) has been shown to be the most efficient vector for liver-directed gene transfer and is currently being evaluated in a clinical trial for treating hemophilia B. In this study, we generated a clinical candidate vector for a proposed OTC gene therapy trial in humans based on a self-complementary AAV8 vector expressing codon-optimized human OTC (hOTCco) under the control of a liver-specific promoter. Codon-optimization dramatically improved the efficacy of OTC gene therapy. Supraphysiological expression levels and activity of hOTC were achieved in adult spf(ash) mice following a single intravenous injection of hOTCco vector. Vector doses as low as 1×10(10) genome copies (GC) achieved robust and sustained correction of the OTCD biomarker orotic aciduria and clinical protection against an ammonia challenge. Functional expression of hOTC in 40% of liver areas was found in mice treated with a low vector dose of 1×10(9) GC. We suggest that the clinical candidate vector we have developed has the potential to achieve therapeutic effects in OTCD patients.
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Affiliation(s)
- Lili Wang
- Gene Therapy Program, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Hiroki Morizono
- Center for Genetic Medicine Research, Children’s National Medical Center, Children’s Research Institute, Washington, D.C., USA
| | - Jianping Lin
- Gene Therapy Program, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Peter Bell
- Gene Therapy Program, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David Jones
- Center for Genetic Medicine Research, Children’s National Medical Center, Children’s Research Institute, Washington, D.C., USA
| | - Deirdre McMenamin
- Gene Therapy Program, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Hongwei Yu
- Gene Therapy Program, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Mark L. Batshaw
- Center for Genetic Medicine Research, Children’s National Medical Center, Children’s Research Institute, Washington, D.C., USA
| | - James M. Wilson
- Gene Therapy Program, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Corresponding author: Department of Pathology and Laboratory Medicine University of Pennsylvania, Philadelphia, PA 19104, USA Phone: 215-898-0226; Fax: 215-494-5444
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104
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Hyperammonemia in review: pathophysiology, diagnosis, and treatment. Pediatr Nephrol 2012; 27:207-22. [PMID: 21431427 DOI: 10.1007/s00467-011-1838-5] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 01/09/2011] [Accepted: 01/12/2011] [Indexed: 12/31/2022]
Abstract
Ammonia is an important source of nitrogen and is required for amino acid synthesis. It is also necessary for normal acid-base balance. When present in high concentrations, ammonia is toxic. Endogenous ammonia intoxication can occur when there is impaired capacity of the body to excrete nitrogenous waste, as seen with congenital enzymatic deficiencies. A variety of environmental causes and medications may also lead to ammonia toxicity. Hyperammonemia refers to a clinical condition associated with elevated ammonia levels manifested by a variety of symptoms and signs, including significant central nervous system (CNS) abnormalities. Appropriate and timely management requires a solid understanding of the fundamental pathophysiology, differential diagnosis, and treatment approaches available. The following review discusses the etiology, pathogenesis, differential diagnosis, and treatment of hyperammonemia.
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105
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Gropman AL, Shattuck K, Prust MJ, Seltzer RR, Breeden AL, Hailu A, Rigas A, Hussain R, VanMeter J. Altered neural activation in ornithine transcarbamylase deficiency during executive cognition: an fMRI study. Hum Brain Mapp 2011; 34:753-61. [PMID: 22110002 DOI: 10.1002/hbm.21470] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 07/26/2011] [Accepted: 08/26/2011] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Ornithine transcarbamylase deficiency (OTCD) is an X-linked urea cycle disorder characterized by hyperammonemia resulting in white matter injury and impairments in working memory and executive cognition. OBJECTIVE To test for differences in BOLD signal activation between subjects with OTCD and healthy controls during a working memory task. DESIGN, SETTING AND PATIENTS Nineteen subjects with OTCD and 21 healthy controls participated in a case-control, IRB-approved study at Georgetown University Medical Center. INTERVENTION An N-back working memory task was performed in a block design using 3T functional magnetic resonance imaging. RESULTS In subjects with OTCD we observed increased BOLD signal in the right dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC) relative to healthy age matched controls. CONCLUSIONS Increased neuronal activation in OTCD subjects despite equivalent task performance points to sub-optimal activation of the working memory network in these subjects, most likely reflecting damage caused by hyperammonemic events. These increases directly relate to our previous finding of reduced frontal white matter integrity in the superior extents of the corpus callosum; key hemispheric connections for these areas. Future studies using higher cognitive load are required to further characterize these effects.
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Affiliation(s)
- Andrea L Gropman
- Department of Neurology, Children's National Medical Center, Washington, DC 20010, USA.
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106
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Häberle J. Varianten von Harnstoffzyklusstörungen. Monatsschr Kinderheilkd 2011. [DOI: 10.1007/s00112-011-2444-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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107
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Gelfand AA, Sznewajs A, Glass HC, Jelin AC, Sherr EH. Clinical Reasoning: An encephalopathic 3-day-old infant. Neurology 2011; 77:e1-5. [PMID: 21727263 DOI: 10.1212/wnl.0b013e3182231407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- A A Gelfand
- Univeristy of California San Francisco, Department of Neurology, Division of Child Neurology, Box 0114, 505 Parnassus Ave., M-798, San Francisco, CA 94143-0114, USA.
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108
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De Bie I, Lemyre E, Lambert M. Favorable long-term outcome following severe neonatal hyperammonemic coma in a patient with argininosuccinate synthetase deficiency. JIMD Rep 2011; 1:83-8. [PMID: 23430833 DOI: 10.1007/8904_2011_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 01/24/2011] [Accepted: 01/25/2011] [Indexed: 03/24/2023] Open
Abstract
This chapter reports on the sequelae-free 8-year follow-up with normal growth, intellectual development, and schooling of a boy with argininosuccinate synthetase deficiency (citrullinemia type I) who was rescued from severe neonatal hyperammonemic coma at 8 days of life (peak ammonia level of 1,058 μmol/L). Important clinical management aspects were: rapidity of response to emergency therapeutic measures that included specific drug regimen, protein restriction, optimal caloric intake and hemodialysis, short coma duration (14 h), possible neuroprotective effect of mild systemic hypothermia during the acute episode, long-term metabolic control with strict compliance to standard of care therapeutic and dietary regimens, active prevention of subsequent hyperammonemic episodes, and early neurodevelopmental evaluations and interventions. We conclude that good long-term neurological outcome following rescue from neonatal hyperammonemic coma is rarely reported but attainable. Prospective registries and interventional studies regrouping clinical data from urea cycle disorders patients will assist clinicians in instituting the appropriate therapeutic measures to provide the best prospect of positive long-term outcome for these children.
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Affiliation(s)
- Isabelle De Bie
- Medical Genetics Division, Department of Pediatrics, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, 3175 Côte Sainte-Catherine, Montréal, QC, Canada, H3T-1C5,
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109
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Abstract
Ornithine transcarbamylase deficiency is an inborn error of metabolism that commonly presents as hyperammonemia in neonates. We present a case of a 2-year-old girl who was referred to a pediatric emergency department for evaluation of hepatitis, an uncommon presentation of ornithine transcarbamylase deficiency. Recognition of late presentations of this disease is important for survival and neurological outcome.
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110
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Assessment of plasma ammonia and glutamine concentrations in urea cycle disorders. Clin Biochem 2011; 44:742-4. [DOI: 10.1016/j.clinbiochem.2011.03.136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 03/01/2011] [Accepted: 03/26/2011] [Indexed: 11/27/2022]
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111
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Erez A, Nagamani SCS, Lee B. Argininosuccinate lyase deficiency-argininosuccinic aciduria and beyond. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2011; 157C:45-53. [PMID: 21312326 DOI: 10.1002/ajmg.c.30289] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The urea cycle consists of six consecutive enzymatic reactions that convert waste nitrogen into urea. Deficiencies of any of these enzymes of the cycle result in urea cycle disorders (UCD), a group of inborn errors of hepatic metabolism that often result in life threatening hyperammonemia. Argininosuccinate lyase (ASL) is a cytosolic enzyme which catalyzes the fourth reaction in the cycle and the first degradative step, that is, the breakdown of argininosuccinic acid to arginine and fumarate. Deficiency of ASL results in an accumulation of argininosuccinic acid in tissues, and excretion of argininosuccinic acid in urine leading to the condition argininosuccinic aciduria (ASA). ASA is an autosomal recessive disorder and is the second most common UCD. In addition to the accumulation of argininosuccinic acid, ASL deficiency results in decreased synthesis of arginine, a feature common to all UCDs except argininemia. Arginine is not only the precursor for the synthesis of urea and ornithine as part of the urea cycle but it is also the substrate for the synthesis of nitric oxide, polyamines, proline, glutamate, creatine, and agmatine. Hence, while ASL is the only enzyme in the body able to generate arginine, at least four enzymes use arginine as substrate: arginine decarboxylase, arginase, nitric oxide synthetase (NOS) and arginine/glycine aminotransferase. In the liver, the main function of ASL is ureagenesis, and hence, there is no net synthesis of arginine. In contrast, in most other tissues, its role is to generate arginine that is designated for the specific cell's needs. While patients with ASA share the acute clinical phenotype of hyperammonemia, encephalopathy, and respiratory alkalosis common to other UCD, they also present with unique chronic complications most probably caused by a combination of tissue specific deficiency of arginine and/or elevation of argininosuccinic acid. This review article summarizes the clinical characterization, biochemical, enzymatic, and molecular features of this disorder. Current treatment, prenatal diagnosis, diagnosis through the newborn screening as well as hypothesis driven future treatment modalities are discussed.
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Affiliation(s)
- Ayelet Erez
- Department of Molecular and Human, Genetics at Baylor College of Medicine, Houston, TX 77030, USA
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112
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Quintero-Rivera F, Deignan JL, Peredo J, Grody WW, Crandall B, Sims M, Cederbaum SD. An exon 1 deletion in OTC identified using chromosomal microarray analysis in a mother and her two affected deceased newborns: implications for the prenatal diagnosis of ornithine transcarbamylase deficiency. Mol Genet Metab 2010; 101:413-6. [PMID: 20817516 DOI: 10.1016/j.ymgme.2010.08.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/06/2010] [Accepted: 08/07/2010] [Indexed: 11/24/2022]
Abstract
We describe the outcome of two consecutive pregnancies with a clinical presentation of ornithine transcarbamylase (OTC) deficiency (OTCD) without a molecular diagnosis. A 119kb deletion on Xp11.4 including the OTC gene was detected in the mother. The same deletion was identified in the blood spots from deceased male newborns. In patients with a clinical and biochemical presentation of OTCD and negative OTC sequencing, whole genome or targeted chromosomal microarray analysis (CMA) with coverage of the OTC and neighboring genes should be performed as a reflex test.
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Affiliation(s)
- Fabiola Quintero-Rivera
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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113
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Brusilow SW, Koehler RC, Traystman RJ, Cooper AJL. Astrocyte glutamine synthetase: importance in hyperammonemic syndromes and potential target for therapy. Neurotherapeutics 2010; 7:452-70. [PMID: 20880508 PMCID: PMC2975543 DOI: 10.1016/j.nurt.2010.05.015] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 05/17/2010] [Accepted: 05/19/2010] [Indexed: 12/21/2022] Open
Abstract
Many theories have been advanced to explain the encephalopathy associated with chronic liver disease and with the less common acute form. A major factor contributing to hepatic encephalopathy is hyperammonemia resulting from portacaval shunting and/or liver damage. However, an increasing number of causes of hyperammonemic encephalopathy have been discovered that present with the same clinical and laboratory features found in acute liver failure, but without liver failure. Here, we critically review the physiology, pathology, and biochemistry of ammonia (i.e., NH3 plus NH4+) and show how these elements interact to constitute a syndrome that clinicians refer to as hyperammonemic encephalopathy (i.e., acute liver failure, fulminant hepatic failure, chronic liver disease). Included will be a brief history of the status of ammonia and the centrality of the astrocyte in brain nitrogen metabolism. Ammonia is normally detoxified in the liver and extrahepatic tissues by conversion to urea and glutamine, respectively. In the brain, glutamine synthesis is largely confined to astrocytes, and it is generally accepted that in hyperammonemia excess glutamine compromises astrocyte morphology and function. Mechanisms postulated to account for this toxicity will be examined with emphasis on the osmotic effects of excess glutamine (the osmotic gliopathy theory). Because hyperammonemia causes osmotic stress and encephalopathy in patients with normal or abnormal liver function alike, the term "hyperammonemic encephalopathy" can be broadly applied to encephalopathy resulting from liver disease and from various other diseases that produce hyperammonemia. Finally, the possibility that a brain glutamine synthetase inhibitor may be of therapeutic benefit, especially in the acute form of liver disease, is discussed.
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Affiliation(s)
- Saul W. Brusilow
- grid.21107.350000000121719311Department of Pediatrics, The Johns Hopkins University School of Medicine, 21287 Baltimore, MD
| | - Raymond C. Koehler
- grid.21107.350000000121719311Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, 21287 Baltimore, MD
| | - Richard J. Traystman
- Office of the Vice Chancellor for Research, Department of Pharmacology, University of Colorado Denver, 80045 Aurora, CO
| | - Arthur J. L. Cooper
- grid.260917.b000000010728151XDepartment of Biochemistry and Molecular Biology, New York Medical College, 10595 Valhalla, NY
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114
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van den Akker CHP, Vlaardingerbroek H, van Goudoever JB. Nutritional support for extremely low-birth weight infants: abandoning catabolism in the neonatal intensive care unit. Curr Opin Clin Nutr Metab Care 2010; 13:327-35. [PMID: 20216411 DOI: 10.1097/mco.0b013e328337d925] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Obviously, the ultimate goal in neonatology is to achieve a functional outcome in premature infants that is comparable to healthy term-born infants. As nutrition is one of the key factors for normal cell growth, providing the right amount and quality of nutrients could prove pivotal for normal development. However, many premature infants are catabolic during the first week of life, which has directly been linked to growth failure, disease, and suboptimal long-term outcome. This review describes the progress in research on parenteral nutrition for premature infants with a focus on amino acids and the influence of nutrition on later outcome. RECENT FINDINGS Although randomized clinical trials on early nutrition for premature infants remain relatively sparse, evidence is accumulating on its beneficial effects both on the short-term and long-term. However, some research also warns for adverse effects. SUMMARY Despite the fact that substantially improved nutritional therapies for preterm neonates have been implemented, still, some reluctance exists when it comes to providing high amounts of nutrition to the most immature infants. Pros and cons are outlined, as well as deficits in knowledge, when it comes to providing the optimal nutrient strategy in the first postnatal phase.
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Affiliation(s)
- Chris H P van den Akker
- Division of Neonatology, Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands
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115
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Abstract
Although the protocol that most experienced metabolic centers in the United States follow for treating acute hyperammonemia in urea cycle disorders (UCDs) is similar to that proposed by Brusilow and Batshaw in the early 1980s, over the years a steady evolution has taken place. Continued developments in intensive care, surgical and hemodialysis techniques, fluid and electrolyte management, cardiovascular support, and emergency transport have contributed to improved management of acute hyperammonemia. Compared to historical data, survival of urea cycle patients has also improved following treatment with alternative pathway therapy, in addition to appropriate supportive care, including the provision of adequate calories to prevent catabolism and promote anabolism and hemodialysis if needed. However, overall neurological outcomes have been suboptimal. There are currently a number of exciting prospective new therapies on the horizon, including novel medications or cell-based treatments. Nevertheless, the therapeutic expertise that is currently in place at centers specializing in management of metabolic emergencies already has the potential to improve survival and outcome in these children significantly. The early identification of UCD patients so that transport to a metabolic treatment center may be carried out without delay continues to be a major area of focus and challenge.
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Affiliation(s)
- Gregory M Enns
- Division of Medical Genetics, Department of Pediatrics, Lucile Packard Children's Hospital, Stanford University, Stanford, CA 94305-5208, USA.
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116
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Ahn BW, Kim HJ, Park HD, Kim WD. A Novel Argininosuccinate Synthetase Gene Mutation in a Korean Family with Type I Citrullinemia. ACTA ACUST UNITED AC 2010. [DOI: 10.5385/jksn.2010.17.2.250] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Affiliation(s)
- Byoung Whan Ahn
- Department of Pediatrics, Daegu Fatima Hospital, Daegu, Korea
| | - Hyun Jeung Kim
- Department of Pediatrics, Daegu Fatima Hospital, Daegu, Korea
| | - Hyung-Doo Park
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Won Duck Kim
- Department of Pediatrics, Daegu Fatima Hospital, Daegu, Korea
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117
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Abstract
Urea cycle disorders (UCD) represent a group of rare inborn errors of metabolism that carry a high risk of mortality and neurological morbidity resulting from the effects of accumulation of ammonia and other biochemical intermediates. These disorders result from single gene defects involved in the detoxification pathway of ammonia to urea. UCD include deficiencies in any of the six enzymes and two membrane transporters involved in urea biosynthesis. It has previously been reported that approximately half of infants who present with hyperammonemic coma in the newborn period die of cerebral edema; and those who survive 3days or more of coma invariably have intellectual disability [1]. In children with partial defects there is an association between the number and severity of recurrent hyperammonemic (HA) episodes (i.e. with or without coma) and subsequent cognitive and neurologic deficits [2]. However, the effects of milder or subclinical HA episodes on the brain are largely unknown. This review discusses the results of neuroimaging studies performed as part of the NIH funded Rare Diseases Clinical Research Center in Urea Cycle Disorders and focuses on biomarkers of brain injury in ornithine transcarbamylase deficiency (OTCD). We used anatomic imaging, functional magnetic resonance imaging (fMRI), diffusion-tensor imaging (DTI), and (1)H/(13)C magnetic resonance spectroscopy (MRS) to study clinically stable adults with partial OTCD. This allowed us to determine alterations in brain biochemistry associated with changes in cell volume and osmolarity and permitted us to identify brain biomarkers of HA. We found that white matter tracts underlying specific pathways involved in working memory and executive function are altered in subjects with OTCD (as measured by DTI), including those heterozygous women who were previously considered asymptomatic. An understanding of the pathogenesis of brain injury in UCD is likely to advance our knowledge of more common disorders of liver dysfunction.
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Affiliation(s)
- Andrea Gropman
- Department of Neurology, Children's National Medical Center, Center for Neuroscience and Behavioral Medicine, Washington, DC 20010, USA.
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118
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Seminara J, Tuchman M, Krivitzky L, Krischer J, Lee HS, LeMons C, Baumgartner M, Cederbaum S, Diaz GA, Feigenbaum A, Gallagher RC, Harding CO, Kerr DS, Lanpher B, Lee B, Lichter-Konecki U, McCandless SE, Merritt JL, Oster-Granite ML, Seashore MR, Stricker T, Summar M, Waisbren S, Yudkoff M, Batshaw ML. Establishing a consortium for the study of rare diseases: The Urea Cycle Disorders Consortium. Mol Genet Metab 2010; 100 Suppl 1:S97-105. [PMID: 20188616 PMCID: PMC2858794 DOI: 10.1016/j.ymgme.2010.01.014] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 01/12/2010] [Accepted: 01/12/2010] [Indexed: 12/12/2022]
Abstract
The Urea Cycle Disorders Consortium (UCDC) was created as part of a larger network established by the National Institutes of Health to study rare diseases. This paper reviews the UCDC's accomplishments over the first 6years, including how the Consortium was developed and organized, clinical research studies initiated, and the importance of creating partnerships with patient advocacy groups, philanthropic foundations and biotech and pharmaceutical companies.
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Affiliation(s)
- Jennifer Seminara
- Children’s National Medical Center, 111 Michigan Avenue, N.W., Washington, DC 20010, USA
| | - Mendel Tuchman
- Children’s National Medical Center, 111 Michigan Avenue, N.W., Washington, DC 20010, USA
| | - Lauren Krivitzky
- Children’s National Medical Center, 111 Michigan Avenue, N.W., Washington, DC 20010, USA
| | - Jeffrey Krischer
- Data Management and Coordinating Center, University of South Florida, Tampa, Florida, USA
| | - Hye-Seung Lee
- Data Management and Coordinating Center, University of South Florida, Tampa, Florida, USA
| | - Cynthia LeMons
- National Urea Cycle Disorders Foundation, Pasadena, California, USA
| | | | | | | | | | | | | | | | - Brendan Lanpher
- Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Brendan Lee
- Baylor College of Medicine, Houston, Texas, USA
| | - Uta Lichter-Konecki
- Children’s National Medical Center, 111 Michigan Avenue, N.W., Washington, DC 20010, USA
| | | | | | - Mary Lou Oster-Granite
- National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Intellectual and Developmental Disabilities Branch, Bethesda, MD, USA
| | | | | | - Marshall Summar
- Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | | | - Marc Yudkoff
- Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Mark L. Batshaw
- Children’s National Medical Center, 111 Michigan Avenue, N.W., Washington, DC 20010, USA
- Corresponding author. Phone: 1- 202-476-4007; Fax: 1-202-476-5988; ; Address: Children’s National Medical Center, 111 Michigan Ave, NW, Washington, DC 20010, USA (ML Batshaw)
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119
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Balasubramaniam S, Rudduck C, Bennetts B, Peters G, Wilcken B, Ellaway C. Contiguous gene deletion syndrome in a female with ornithine transcarbamylase deficiency. Mol Genet Metab 2010; 99:34-41. [PMID: 19783189 DOI: 10.1016/j.ymgme.2009.08.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 08/21/2009] [Accepted: 08/21/2009] [Indexed: 10/20/2022]
Abstract
OTC deficiency, a partially dominant X-linked trait, is the most frequent inborn error of the urea cycle. We describe a female patient with a contiguous gene deletion syndrome encompassing the OTC, DMD, RPGR, CYBB and XK genes, amongst others, only manifesting features of OTC deficiency. Molecular characterization was ascertained by MLPA and confirmed by CGH microarray, which revealed an 8.7 Mb deletion of the X-chromosome. Complete de novo deletion of the OTC gene led to a severe clinical phenotype in the proband. The application of high resolution molecular genetic techniques such as MLPA and array CGH, in mutation negative OTC cases allows the identification of chromosomal rearrangements, such as large deletions and provides information for accurate genetic counseling and prenatal diagnosis.
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Affiliation(s)
- S Balasubramaniam
- Genetic Metabolic Disorders Service, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia
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120
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Braissant O. Current concepts in the pathogenesis of urea cycle disorders. Mol Genet Metab 2010; 100 Suppl 1:S3-S12. [PMID: 20227314 DOI: 10.1016/j.ymgme.2010.02.010] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2009] [Accepted: 02/08/2010] [Indexed: 12/14/2022]
Abstract
The common feature of urea cycle diseases (UCD) is a defect in ammonium elimination in liver, leading to hyperammonemia. This excess of circulating ammonium eventually reaches the central nervous system, where the main toxic effects of ammonium occur. These are reversible or irreversible, depending on the age of onset as well as the duration and the level of ammonium exposure. The brain is much more susceptible to the deleterious effects of ammonium during development than in adulthood, and surviving UCD patients may develop cortical and basal ganglia hypodensities, cortical atrophy, white matter atrophy or hypomyelination and ventricular dilatation. While for a long time, the mechanisms leading to these irreversible effects of ammonium exposure on the brain remained poorly understood, these last few years have brought new data showing in particular that ammonium exposure alters several amino acid pathways and neurotransmitter systems, cerebral energy, nitric oxide synthesis, axonal and dendritic growth, signal transduction pathways, as well as K(+) and water channels. All these effects of ammonium on CNS may eventually lead to energy deficit, oxidative stress and cell death. Recent work also proposed neuroprotective strategies, such as the use of NMDA receptor antagonists, nitric oxide inhibitors, creatine and acetyl-l-carnitine, to counteract the toxic effects of ammonium. Better understanding the pathophysiology of ammonium toxicity to the brain under UCD will allow the development of new strategies for neuroprotection.
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Affiliation(s)
- Olivier Braissant
- Inborn Errors of Metabolism, Clinical Chemistry Laboratory, Centre Hospitalier Universitaire Vaudois and University of Lausanne, CI 02/33, Lausanne, Switzerland.
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121
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Valproic Acid-induced hyperammonemia in the elderly: a review of the literature. Case Rep Med 2009; 2009:802121. [PMID: 19724652 PMCID: PMC2731545 DOI: 10.1155/2009/802121] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 07/06/2009] [Indexed: 01/09/2023] Open
Abstract
Valproic acid and its derivatives are commonly used to treat many psychiatric conditions in the elderly. Hyperammonemia is a less common but important side effect of these drugs. The elderly patient appears highly vulnerable to this side effect of this group of medications. In this paper, we systematically review the published literature for hyperammonemia induced by valproic acid and its derivatives. We describe the three reported cases and review possible treatment strategies for this condition.
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122
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Cranial MRI in acute hyperammonemic encephalopathy. Pediatr Neurol 2009; 41:139-42. [PMID: 19589465 DOI: 10.1016/j.pediatrneurol.2009.02.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 02/16/2009] [Accepted: 02/23/2009] [Indexed: 11/20/2022]
Abstract
Cranial magnetic resonance imaging was performed in three cases of acute hyperammonemic encephalopathy with three diverse etiologies: infantile citrullinemia, acute hepatic encephalopathy, and proximal urea cycle disorder. All three patients exhibited diffuse extensive cortical signal changes and swelling. Neurologic outcome was poor in all three cases. Knowledge of the magnetic resonance imaging findings of hyperammonemic encephalopathy may help in early diagnosis and treatment and could influence the neurologic outcome.
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123
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Krivitzky L, Babikian T, Lee HS, Thomas NH, Burk-Paull KL, Batshaw ML. Intellectual, adaptive, and behavioral functioning in children with urea cycle disorders. Pediatr Res 2009; 66:96-101. [PMID: 19287347 PMCID: PMC2746951 DOI: 10.1203/pdr.0b013e3181a27a16] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Inborn errors of urea synthesis lead to an accumulation of ammonia in blood and brain and result in high rates of mortality and neurodevelopmental disability. This study seeks to characterize the cognitive, adaptive, and emotional/behavioral functioning of children with urea cycle disorders (UCDs). These domains were measured through testing and parent questionnaires in 92 children with UCDs [33 neonatal onset (NO), 59 late onset (LO)]. Results indicate that children who present with NO have poorer outcome than those who present later in childhood. Approximately half of the children with NO performed in the range of intellectual disability (ID), including a substantial number ( approximately 30%) who were severely impaired. In comparison, only a quarter of the LO group was in the range of ID. There is also evidence that the UCD group has difficulties in aspects of emotional/behavioral and executive skills domains. In conclusion, children with UCDs present with a wide spectrum of cognitive outcomes. Children with NO disease have a much higher likelihood of having an ID, which becomes even more evident with increasing age. However, even children with LO UCDs demonstrate evidence of neurocognitive and behavioral impairment, particularly in aspects of attention and executive functioning.
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Affiliation(s)
- Lauren Krivitzky
- Department of Psychiatry and Behavioral Sciences, George Washington University School of Medicine and Health Sciences, Washington, DC 20010, USA.
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124
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Bruggink JLM, van Spronsen FJ, Wijnberg-Williams BJ, Bos AF. Pilot use of the early motor repertoire in infants with inborn errors of metabolism: outcomes in early and middle childhood. Early Hum Dev 2009; 85:461-5. [PMID: 19403245 DOI: 10.1016/j.earlhumdev.2009.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2008] [Revised: 01/10/2009] [Accepted: 04/03/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND Predicting later outcome in neonates presenting with severe inborn errors of metabolism (IEM) is difficult. The assessment of the early motor repertoire is a reliable method of evaluating the integrity of the central nervous system in young infants. This method is based on an age-specific qualitative assessment of general movements (GMs, 0-8 weeks of age), fidgety movements (FMs) and the concurrent motor repertoire (9-20 weeks of age). AIM To determine the quality of the early motor repertoire (at 0-20 weeks post term age) in relation to later neurological outcome in infants with severe IEM. STUDY DESIGN Prospective cohort study. The quality of the motor repertoire was assessed from serial videotape recordings. SUBJECTS Five infants with IEM. Four presented with a severe IEM in the neonatal period: an undefined gluconeogenesis defect, propionic acidemia, arginosuccinate synthetase and arginosuccinate lyase deficiency. One neonate was antenatally diagnosed with arginosuccinate synthetase deficiency. OUTCOME MEASURES Outcome at the age of at least 18 m was determined by neurological examination and developmental tests. RESULTS All infants initially had abnormal GMs: hypokinesia, followed by GMs of a poor repertoire. The quality of the early motor repertoire normalised in 3 infants, and remained abnormal in 2. The more severe and persistent abnormalities of the motor repertoire were considered with the more abnormal neurological and developmental scores, later on. CONCLUSIONS The quality of the early motor repertoire might be related to later neurological outcome in infants with inborn errors of metabolism.
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Affiliation(s)
- J L M Bruggink
- Department of Pediatrics, Division of Neonatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
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125
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Gropman AL, Sailasuta N, Harris KC, Abulseoud O, Ross BD. Ornithine transcarbamylase deficiency with persistent abnormality in cerebral glutamate metabolism in adults. Radiology 2009; 252:833-41. [PMID: 19567648 DOI: 10.1148/radiol.2523081878] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To determine cerebral glutamate turnover rate in partial-ornithine transcarbamylase deficiency (OTCD) patients by using carbon 13 ((13)C) magnetic resonance (MR) spectroscopy. MATERIALS AND METHODS The study was performed with approval of the institutional review board, in compliance with HIPAA regulations, and with written informed consent of the subjects. MR imaging, hydrogen 1 ((1)H) MR spectroscopy, and (13)C MR spectroscopy were performed at 1.5 T in 10 subjects, six patients with OTCD and four healthy control subjects, who were in stable condition. Each received intravenous (13)C-glucose (0.2 g/kg), C1 or C2 position, as a 15-minute bolus. Cerebral metabolites were determined with proton decoupling in a parieto-occipital region (n = 9) and without proton decoupling in a frontal region (n = 1) during 60-120 minutes. RESULTS Uptake and removal of cerebral glucose ([1-(13)C]-glucose or [2-(13)C]-glucose) were comparable in healthy control subjects and subjects with OTCD (P = .1). Glucose C1 was metabolized to glutamate C4 and glucose C2 was metabolized to glutamate C5 at comparable rates, both of which were significantly reduced in OTCD (combined, P = .04). No significant differences in glutamine formation were found in subjects with OTCD (P = .1). [2-(13)C]-glucose and its metabolic products were observed in anterior cingulate gyrus without proton decoupling in one subject with OTCD. CONCLUSION Treatments that improve cerebral glucose metabolism and glutamate neurotransmission may improve neurologic outcome in patients with OTCD, in whom prevention and treatment of hyperammonemic episodes appear to be insufficient.
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Affiliation(s)
- Andrea L Gropman
- Department of Neurology, Children's National Medical Center, Washington, DC, USA
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126
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Ishida T, Hiroma T, Hashikura Y, Horiuchi M, Kobayashi K, Nakamura T. Early neonatal onset carbamoyl-phosphate synthase 1 deficiency treated with continuous hemodiafiltration and early living-related liver transplantation. Pediatr Int 2009; 51:409-10. [PMID: 19500281 DOI: 10.1111/j.1442-200x.2009.02831.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Takefumi Ishida
- Division of Neonatology, Nagano Children's Hospital, Nagano 399-8288, Japan
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127
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Picca S, Bartuli A, Dionisi-Vici C. Medical management and dialysis therapy for the infant with an inborn error of metabolism. Semin Nephrol 2008; 28:477-80. [PMID: 18790367 DOI: 10.1016/j.semnephrol.2008.05.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Optimal care of the neonate with hyperammonemia requires expertise in the evaluation, medical management, and decision to initiate dialytic therapy, and therefore compels expeditious collaboration between neonatal intensive care physicians, medical geneticists, and pediatric nephrologists. Neonatal and dialysis nursing expertise also is paramount for the successful provision of dialysis therapy in this setting. The current article addresses the underlying causes, medical management strategies, and dialytic therapy considerations in caring for the neonate with hyperammonemia.
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Affiliation(s)
- Stefano Picca
- Department of Nephrology and Urology, Dialysis Unit, Bambino Gesù Children's Research Hospital, Rome, Italy.
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128
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Brunetti-Pierri N, Clarke C, Mane V, Palmer DJ, Lanpher B, Sun Q, O'Brien W, Lee B. Phenotypic correction of ornithine transcarbamylase deficiency using low dose helper-dependent adenoviral vectors. J Gene Med 2008; 10:890-6. [PMID: 18563850 DOI: 10.1002/jgm.1218] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Helper-dependent adenoviral vectors (HDAd) can mediate long-term phenotypic correction in the ornithine transacarbamylase (OTC)-deficient mice model with negligible chronic toxicity. However, the high doses required for metabolic correction will result in systemic inflammatory response syndrome in humans. This acute toxicity represents the major obstacle for clinical applications of HDAd vectors for the treatment of OTC deficiency. Strategies for reducing the dose necessary for disease correction are highly desirable because HDAd acute toxicity is clearly dose-dependent. METHODS We analysed a potent expression cassette and the hydrodynamic injection for the ability to reduce the HDAd dose necessary for phenotypic correction in OTC-deficient spf-ash mice. RESULTS We have developed a vector containing a potent expression cassette expressing the OTC transgene, which allowed phenotypic correction at lower doses. Our results suggest that vector expressing greater OTC levels allows correction of orotic acid overproduction at lower doses that make clinical translation more relevant. We were able to further reduce the minimal effective dose by delivering the vector through the hydrodynamic injection technique. CONCLUSIONS Vectors containing the expression cassette used in the present study, combined with other strategies for improving HDAd therapeutic index, will likely permit application of these vectors for the treatment of OTC deficiency as well as other urea cycle disorders.
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Affiliation(s)
- Nicola Brunetti-Pierri
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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129
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Enns GM. Neurologic damage and neurocognitive dysfunction in urea cycle disorders. Semin Pediatr Neurol 2008; 15:132-9. [PMID: 18708004 DOI: 10.1016/j.spen.2008.05.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Although the survival of patients who have urea cycle disorders has improved with the use of modalities such as alternative pathway therapy and hemodialysis, neurologic outcome is suboptimal. Patients often manifest with a variety of neurologic abnormalities, including cerebral edema, seizures, cognitive impairment, and psychiatric illness. Current hypotheses of the pathogenesis underlying brain dysfunction in these patients have focused on several lines of investigation, including the role of glutamine in causing cerebral edema, mitochondrial dysfunction leading to energy failure and the production of free radicals, and altered neurotransmitter metabolism. Advances in understanding the pathogenetic mechanisms underlying brain impairment in urea cycle disorders may lead to the development of therapies designed to interfere with the molecular cascade that ultimately leads to cerebral edema and other brain pathological findings.
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Affiliation(s)
- Gregory M Enns
- Department of Pediatrics, Division of Medical Genetics, Lucile Packard Children's Hospital, Stanford University, Stanford, CA 94305, USA.
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130
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Gropman AL, Fricke ST, Seltzer RR, Hailu A, Adeyemo A, Sawyer A, van Meter J, Gaillard WD, McCarter R, Tuchman M, Batshaw M. 1H MRS identifies symptomatic and asymptomatic subjects with partial ornithine transcarbamylase deficiency. Mol Genet Metab 2008; 95:21-30. [PMID: 18662894 PMCID: PMC3724938 DOI: 10.1016/j.ymgme.2008.06.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2008] [Revised: 06/13/2008] [Accepted: 06/13/2008] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To evaluate brain metabolism in subjects with partial ornithine transcarbamylase deficiency (OTCD) utilizing (1)H MRS. METHODS Single-voxel (1)H MRS was performed on 25 medically-stable adults with partial OTCD, and 22 similarly aged controls. Metabolite concentrations from frontal and parietal white matter (FWM, PWM), frontal gray matter (FGM), posterior cingulate gray matter (PCGM), and thalamus (tha) were compared with controls and IQ, plasma ammonia, glutamine, and disease severity. RESULTS Cases ranged from 19 to 59 years; average 34 years; controls ranged from 18 to 59 years; average 33 years. IQ scores were lower in cases (full scale 111 vs. 126; performance IQ 106 vs. 117). Decreased myoinositol (mI) in FWM (p=0.005), PWM (p<0.001), PCGM (p=0.003), and tha (p=0.004), identified subjects with OTCD, including asymptomatic heterozygotes. Glutamine (gln) was increased in FWM (p<0.001), PWM (p<0.001), FGM (p=0.002), and PCGM (p=0.001). Disease severity was inversely correlated with [mI] in PWM (r=-0.403; p=0.046) and directly correlated with [gln] in PCGM (r=0.548; p=0.005). N-Acetylaspartate (NAA) was elevated in PWM (p=0.002); choline was decreased in FWM (p=0.001) and tha (p=0.002). There was an inverse relationship between [mI] and [gln] in cases only. Total buffering capacity (measured by [mI/mI+gln] ratio, a measure of total osmolar capacity) was inversely correlated with disease severity in FWM (r=-0.479; p=0.018), PWM (r=-0.458; p=0.021), PCGM (r=-0.567; p=0.003), and tha (r=-0.345; p=0.037). CONCLUSION Brain metabolism is impaired in partial OTCD. Depletion of mI and total buffering capacity are inversely correlated with disease severity, and serve as biomarkers.
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Affiliation(s)
- A L Gropman
- Department of Neurology, Children's National Medical Center, George Washington University School of Medicine and Health Sciences, Washington, DC 20010, USA.
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131
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Lichter-Konecki U. Profiling of astrocyte properties in the hyperammonaemic brain: shedding new light on the pathophysiology of the brain damage in hyperammonaemia. J Inherit Metab Dis 2008; 31:492-502. [PMID: 18683079 DOI: 10.1007/s10545-008-0834-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2007] [Revised: 05/30/2008] [Accepted: 06/03/2008] [Indexed: 10/21/2022]
Abstract
Acute hyperammonaemia (HA) causes cerebral oedema and severe brain damage in patients with urea cycle disorders (UCDs) or acute liver failure (ALF). Chronic HA is associated with developmental delay and intellectual disability in patients with UCDs and with neuropsychiatric symptoms in patients with chronic liver failure. Treatment often cannot prevent severe brain injury and neurological sequelae. The causes of the brain oedema in hyperammonaemic encephalopathy (HAE) have been subject of intense controversy among physicians and scientists working in this field. Currently favoured hypotheses are astrocyte swelling due to increased intracellular glutamine content and neuronal cell death due to excitotoxicity caused by elevated extracellular glutamate levels. While many researchers focus on these mechanisms of cytotoxicity, others emphasize vascular causes of brain oedema. New data gleaned from expression profiling of astrocytes acutely isolated from hyperammonaemic mouse brains point to disturbed water and potassium homeostasis as regulated by astrocytes at the brain microvasculature and in the perisynaptic space as a potential mechanism of brain oedema development in hyperammonaemia.
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Affiliation(s)
- U Lichter-Konecki
- Center for Neuroscience Research, and Division of Genetics & Metabolism, Children's National Medical Center, Washington, DC 20010-2970, USA.
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132
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Collen JF, Das NP, Koff JM, Neff RT, Abbott KC. Hemodialysis for hyperammonemia associated with ornithine transcarbamylase deficiency. APPLICATION OF CLINICAL GENETICS 2008; 1:1-5. [PMID: 23776342 DOI: 10.2147/tacg.s3536] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Acute hyperammonemia is a medical emergency requiring rapid recognition and treatment to prevent devastating neurologic sequelae. Its varying etiologies include primary hepatic failure, drug toxicity, infection, and inherited disorders of metabolism. Ornithine transcarbamylase (OTC) deficiency is the most common inherited urea cycle disorder and can result in hyperammonemic encephalopathy and coma, often presenting in the newborn or early childhood. Partial deficiencies of the enzyme can present later in adulthood with protean neuropsychiatric signs and symptoms. Early recognition and management of metabolic encephalopathy is crucial to avoid neurologic damage, and may require hemodialysis for rapid removal of ammonia, with adjunctive medications and dietary modifications to decrease endogenous nitrogen production and activate alternate pathways of nitrogen excretion. We present the case of an adult patient with partial OTC deficiency who presented with encephalopathy, coma, and seizures, accompanied by hyperammonemia and treated acutely with hemodialysis.
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133
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Lichter-Konecki U, Mangin JM, Gordish-Dressman H, Hoffman EP, Gallo V. Gene expression profiling of astrocytes from hyperammonemic mice reveals altered pathways for water and potassium homeostasis in vivo. Glia 2008; 56:365-77. [PMID: 18186079 DOI: 10.1002/glia.20624] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Acute hyperammonemia (HA) causes cerebral edema and brain damage in children with urea cycle disorders (UCDs) and in patients in acute liver failure. Chronic HA is associated with developmental delay and mental retardation in children with UCDs, and with neuropsychiatric symptoms in patients with chronic liver failure. Astrocytes are a major cellular target of hyperammonemic encephalopathy, and changes occurring in these cells are thought to be causally related to the brain edema of acute HA. To study the effect of HA on astrocytes in vivo, we crossed the Otc(spf) mouse, a mouse with the X-linked UCD ornithine transcarbamylase (OTC) deficiency, with the hGFAP-EGFP mouse, a mouse selectively expressing green fluorescent protein in astrocytes. We used FACS to purify astrocytes from the brains of hyperammonemic and healthy Otcspf/GFAP-EGFP mice. RNA isolated from these astrocytes was used in microarray expression analyses and qRT-PCR. When compared with healthy littermates, we observed a significant downregulation of the gap-junction channel connexin 43 (Cx43) the water channel aquaporin 4 (Aqp4) genes, and the astrocytic inward-rectifying potassium channel (Kir) genes Kir4.1 and Kir5.1 in hyperammonemic mice. Aqp4, Cx43, and Kir4.1/Kir5.1 are co-localized to astrocytic end-feet at the brain vasculature, where they regulate potassium and water transport. Since, NH4+ ions can permeate water and K+-channels, downregulation of these three channels may be a direct effect of elevated blood ammonia levels. Our results suggest that alterations in astrocyte-mediated water and potassium homeostasis in brain may be key to the development of the brain edema.
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Affiliation(s)
- Uta Lichter-Konecki
- Center for Neuroscience Research, Children's National Medical Center, Washington, DC 20010, USA
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134
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Abstract
The aim of this article is to provide essential information for hepatologists, who primarily care for adults, regarding liver-based inborn errors of metabolism with particular reference to those that may be treatable with liver transplantation and to provide adequate references for more in-depth study should one of these disease states be encountered.
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Affiliation(s)
- Keli Hansen
- Division of Transplant Surgery and Division of Gastroenterology, Children's Hospital and Regional Medical Center, Seattle, WA 98105, USA
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135
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Abstract
The aim of this article is to provide essential information for hepatologists, who primarily care for adults, regarding liver-based inborn errors of metabolism with particular reference to those that may be treatable with liver transplantation and to provide adequate references for more in-depth study should one of these disease states be encountered.
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Affiliation(s)
- Keli Hansen
- Children's Hospital and Regional Medical Center, Seattle, WA 98105, USA.
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136
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Leonard JV, Ward Platt MP, Morris AAM. Hypothesis: proposals for the management of a neonate at risk of hyperammonaemia due to a urea cycle disorder. Eur J Pediatr 2008; 167:305-9. [PMID: 17436013 DOI: 10.1007/s00431-007-0486-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Revised: 03/19/2007] [Accepted: 03/20/2007] [Indexed: 10/23/2022]
Abstract
It is difficult to prevent hyperammonaemia in patients with urea cycle disorders that present in the newborn period. This is true, even if treatment is started prospectively because of an affected relative. We propose several additional measures that could be used in conjunction with conventional therapy to improve the metabolic control. Catabolism could be reduced by delivering the babies by elective caesarean section, by starting intravenous glucose immediately after delivery and, possibly, by using beta-blockers or octreotide and insulin. The effectiveness of sodium benzoate and sodium phenylbutyrate might be increased by giving phenobarbital to the mother before delivery and subsequently to the baby to induce the enzymes for conjugation. We would expect the proposed measures to reduce the risk of hyperammonaemia and to improve the outcome for these patients. They have not, however, previously been used in this context, so families would need to be counselled carefully and controlled studies should be undertaken.
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Affiliation(s)
- James Vivian Leonard
- Clinical and Molecular Genetics Unit, Institute of Child Health, University College London, London, UK
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137
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Puppi J, Tan N, Mitry RR, Hughes RD, Lehec S, Mieli-Vergani G, Karani J, Champion MP, Heaton N, Mohamed R, Dhawan A. Hepatocyte transplantation followed by auxiliary liver transplantation--a novel treatment for ornithine transcarbamylase deficiency. Am J Transplant 2008; 8:452-7. [PMID: 18211511 DOI: 10.1111/j.1600-6143.2007.02058.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We report the first successful use of hepatocyte transplantation as a bridge to subsequent auxiliary partial orthotopic liver transplantation (APOLT) in a child antenatally diagnosed with severe ornithine transcarbamylase (OTC) deficiency. A total of 1.74 x 10(9) fresh and cryopreserved hepatocytes were administered intraportally into the liver over a period of 6 months. Immunosuppression was with tacrolimus and prednisolone. A sustained decrease in ammonia levels and a gradual increase in serum urea were observed except during episodes of sepsis in the first 6 months of life. The patient was able to tolerate a normal protein intake and presented a normal growth and neurological development. APOLT was successfully performed at 7 months of age. We conclude that hepatocyte transplantation can be used in conjunction with APOLT as an effective treatment for severe OTC-deficient patients, improving neurodevelopmental outcomes.
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Affiliation(s)
- J Puppi
- Institute of Liver Studies, King's College Hospital, London, UK
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138
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Pela I, Seracini D, Donati MA, Lavoratti G, Pasquini E, Materassi M. Peritoneal dialysis in neonates with inborn errors of metabolism: is it really out of date? Pediatr Nephrol 2008; 23:163-8. [PMID: 17899205 DOI: 10.1007/s00467-007-0607-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 08/04/2007] [Accepted: 08/06/2007] [Indexed: 12/31/2022]
Abstract
Peritoneal and extracorporeal dialysis are used to treat newborns affected by inborn errors of metabolism to minimize the effects of the acute accumulation of neurotoxic metabolites that can produce irreversible and severe neurological damage and even death. In recent papers, extracorporeal dialysis has been described as more effective than peritoneal dialysis in improving the prognosis in newborns with inborn errors of metabolism and hyperammonemia. However, it appears that the outcome is primarily related to the duration of neonatal hyperammonemic coma. Here we report seven newborns with hyperammonemia caused by inborn errors of metabolism (five with organic acidemias, two with urea-cycle disorders). They received dietetic and pharmacological treatment as well as peritoneal dialysis. Four of the five patients with organic acidemia survived with and without mild neurological impairment (follow-up 3.5-10 years). One died from bacterial sepsis after peritoneal dialysis was discontinued and the peritoneal catheter was removed. One of the two patients affected by urea-cycle disorders, a boy, died during the neonatal period, and the other, a girl, died at the age of 13 months due to severe neurological damage. Our results demonstrate that peritoneal dialysis may still be an effective treatment for neonatal hyperammonemia caused by inborn errors of metabolism. Furthermore, peritoneal dialysis can be administered quickly and easily in all settings, clearly an advantage when fast intervention is so crucial.
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Affiliation(s)
- Ivana Pela
- Pediatrics, Meyer Hospital, Via Luca Giordano 13, Florence 50135, Italy
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139
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Abstract
Patients experiencing acute elevations of ammonia present to the ICU with encephalopathy, which may progress quickly to cerebral herniation. Patient survival requires immediate treatment of intracerebral hypertension and the reduction of ammonia levels. When hyperammonemia is not thought to be the result of liver failure, treatment for an occult disorder of metabolism must begin prior to the confirmation of an etiology. This article reviews ammonia metabolism, the effects of ammonia on the brain, the causes of hyperammonemia, and the diagnosis of inborn errors of metabolism in adult patients.
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Affiliation(s)
- Alison S Clay
- Department of Surgery and Medicine, Duke University Medical Center, Box 2945, Durham, NC 27710, USA.
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140
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Gropman AL, Summar M, Leonard JV. Neurological implications of urea cycle disorders. J Inherit Metab Dis 2007; 30:865-79. [PMID: 18038189 PMCID: PMC3758693 DOI: 10.1007/s10545-007-0709-5] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 10/13/2007] [Accepted: 10/18/2007] [Indexed: 12/19/2022]
Abstract
The urea cycle disorders constitute a group of rare congenital disorders caused by a deficiency of the enzymes or transport proteins required to remove ammonia from the body. Via a series of biochemical steps, nitrogen, the waste product of protein metabolism, is removed from the blood and converted into urea. A consequence of these disorders is hyperammonaemia, resulting in central nervous system dysfunction with mental status changes, brain oedema, seizures, coma, and potentially death. Both acute and chronic hyperammonaemia result in alterations of neurotransmitter systems. In acute hyperammonaemia, activation of the NMDA receptor leads to excitotoxic cell death, changes in energy metabolism and alterations in protein expression of the astrocyte that affect volume regulation and contribute to oedema. Neuropathological evaluation demonstrates alterations in the astrocyte morphology. Imaging studies, in particular (1)H MRS, can reveal markers of impaired metabolism such as elevations of glutamine and reduction of myoinositol. In contrast, chronic hyperammonaemia leads to adaptive responses in the NMDA receptor and impairments in the glutamate-nitric oxide-cGMP pathway, leading to alterations in cognition and learning. Therapy of acute hyperammonaemia has relied on ammonia-lowering agents but in recent years there has been considerable interest in neuroprotective strategies. Recent studies have suggested restoration of learning abilities by pharmacological manipulation of brain cGMP with phosphodiesterase inhibitors. Thus, both strategies are intriguing areas for potential investigation in human urea cycle disorders.
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Affiliation(s)
- A L Gropman
- Department of Neurology, Children's National Medical Center and the George Washington University of the Health Sciences, 111 Michigan Avenue, N. W., Washington, DC 20010, USA.
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141
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Cagnon L, Braissant O. Hyperammonemia-induced toxicity for the developing central nervous system. ACTA ACUST UNITED AC 2007; 56:183-97. [PMID: 17881060 DOI: 10.1016/j.brainresrev.2007.06.026] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 06/15/2007] [Accepted: 06/15/2007] [Indexed: 12/12/2022]
Abstract
In pediatric patients, hyperammonemia can be caused by various acquired or inherited disorders such as urea cycle deficiencies or organic acidemias. The brain is much more susceptible to the deleterious effects of ammonium during development than in adulthood. Hyperammonemia can provoke irreversible damages to the developing central nervous system that lead to cortical atrophy, ventricular enlargement and demyelination, responsible for cognitive impairment, seizures and cerebral palsy. Until recently, the mechanisms leading to these irreversible cerebral damages were poorly understood. Using experimental models allowing the analysis of the neurotoxic effects of ammonium on the developing brain, these last years have seen the emergence of new clues showing that ammonium exposure alters several amino acid pathways and neurotransmitter systems, as well as cerebral energy metabolism, nitric oxide synthesis, oxidative stress, mitochondrial permeability transition and signal transduction pathways. Those alterations may explain neuronal loss and impairment of axonal and dendritic growth observed in the different models of congenital hyperammonemia. Some neuroprotective strategies such as the potential use of NMDA receptor antagonists, nitric oxide inhibitors, creatine and acetyl-l-carnitine have been suggested to counteract these toxic effects. Unraveling the molecular mechanisms involved in the chain of events leading to neuronal dysfunction under hyperammonemia may be useful to develop new potential strategies for neuroprotection.
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Affiliation(s)
- Laurène Cagnon
- Clinical Chemistry Laboratory, Centre Hospitalier Universitaire Vaudois and University of Lausanne, CI 02/33, Avenue Pierre-Decker 2, CH-1011 Lausanne, Switzerland
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142
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de Boo HA, Harding JE. Protein metabolism in preterm infants with particular reference to intrauterine growth restriction. Arch Dis Child Fetal Neonatal Ed 2007; 92:F315-9. [PMID: 17585098 PMCID: PMC2675441 DOI: 10.1136/adc.2006.099697] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/15/2006] [Indexed: 11/03/2022]
Abstract
There is growing evidence that neonatal and long-term morbidity in preterm infants, particularly those born before 32 weeks' gestation, can be modified by attained growth rate in the neonatal period. Guidelines for optimal growth and the nutritional intakes, particular of protein, required to achieve this are not well defined. Due to delays in postnatal feeding and a lack of energy stores developed in the last trimester of pregnancy, preterm infants often suffer early postnatal catabolism until feeding is established. There are indications that infants born with intrauterine growth restriction have perturbations in protein metabolism. Therefore, they may have different protein requirements than appropriate for gestational age infants. This review summarises what is known about protein requirements and metabolism in the fetus and preterm infant, with particular emphasis on the distinct requirements of the growth-restricted infant.
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Affiliation(s)
- H A de Boo
- Liggins Institute, University of Auckland, Private Bag 92019, Auckland, New Zealand.
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143
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Bunchman TE, Barletta GM, Winters JW, Gardner JJ, Crumb TL, McBryde KD. Phenylacetate and benzoate clearance in a hyperammonemic infant on sequential hemodialysis and hemofiltration. Pediatr Nephrol 2007; 22:1062-5. [PMID: 17277951 DOI: 10.1007/s00467-007-0436-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 12/13/2006] [Accepted: 12/15/2006] [Indexed: 11/27/2022]
Abstract
An infant with a suspected inborn metabolism error was treated with a metabolic cocktail of intravenous sodium phenylacetate (NaPh) and sodium benzoate (NaBz) for hyperammonemia. Sequential hemodialysis (HD) then hemofiltration (HF) was performed due to hyperammonemia. Dialytic and convective clearance (K; ml/min) of ammonia, NaPh, and NaBz was measured. The K of ammonia was 57 and 37 for HD and HF, respectively. The K of NaBz was 37 and 12 for HD and HF, respectively. The K of NaPh was 38 and 14 ml/min for HD and HF, respectively. Despite high clearance of both NaPh and NaBz by HD and HF, the hyperammonemia was corrected.
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Affiliation(s)
- Timothy E Bunchman
- Pediatric Nephrology, Dialysis and Transplantation, Helen DeVos Children's Hospital, Grand Rapids, MI, USA.
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144
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Enns GM, Berry SA, Berry GT, Rhead WJ, Brusilow SW, Hamosh A. Survival after treatment with phenylacetate and benzoate for urea-cycle disorders. N Engl J Med 2007; 356:2282-92. [PMID: 17538087 DOI: 10.1056/nejmoa066596] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND The combination of intravenous sodium phenylacetate and sodium benzoate has been shown to lower plasma ammonium levels and improve survival in small cohorts of patients with historically lethal urea-cycle enzyme defects. METHODS We report the results of a 25-year, open-label, uncontrolled study of sodium phenylacetate and sodium benzoate therapy (Ammonul, Ucyclyd Pharma) in 299 patients with urea-cycle disorders in whom there were 1181 episodes of acute hyperammonemia. RESULTS Overall survival was 84% (250 of 299 patients). Ninety-six percent of the patients survived episodes of hyperammonemia (1132 of 1181 episodes). Patients over 30 days of age were more likely than neonates to survive an episode (98% vs. 73%, P<0.001). Patients 12 or more years of age (93 patients), who had 437 episodes, were more likely than all younger patients to survive (99%, P<0.001). Eighty-one percent of patients who were comatose at admission survived. Patients less than 30 days of age with a peak ammonium level above 1000 micromol per liter (1804 microg per deciliter) were least likely to survive a hyperammonemic episode (38%, P<0.001). Dialysis was also used in 56 neonates during 60% of episodes and in 80 patients 30 days of age or older during 7% of episodes. CONCLUSIONS Prompt recognition of a urea-cycle disorder and treatment with both sodium phenylacetate and sodium benzoate, in conjunction with other therapies, such as intravenous arginine hydrochloride and the provision of adequate calories to prevent catabolism, effectively lower plasma ammonium levels and result in survival in the majority of patients. Hemodialysis may also be needed to control hyperammonemia, especially in neonates and older patients who do not have a response to intravenous sodium phenylacetate and sodium benzoate.
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Affiliation(s)
- Gregory M Enns
- Department of Pediatrics, Division of Medical Genetics, Stanford University, School of Medicine, Lucile Packard Children's Hospital, Stanford, CA 94305-5208, USA.
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145
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Nagasaka H, Yorifuji T, Murayama K, Kubota M, Kurokawa K, Murakami T, Kanazawa M, Takatani T, Ogawa A, Ogawa E, Yamamoto S, Adachi M, Kobayashi K, Takayanagi M. Effects of arginine treatment on nutrition, growth and urea cycle function in seven Japanese boys with late-onset ornithine transcarbamylase deficiency. Eur J Pediatr 2006; 165:618-24. [PMID: 16703326 DOI: 10.1007/s00431-006-0143-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Accepted: 03/01/2006] [Indexed: 12/17/2022]
Abstract
BACKGROUND The aim of this study was to investigate the effects of arginine on nutrition, growth and urea cycle function in boys with late-onset ornithine transcarbamylase deficiency (OTCD). Seven Japanese boys with late-onset OTCD enrolled in this study resumed arginine treatment after the cessation of this therapy for a few years. Clinical presentations such as vomiting and unconsciousness, plasma amino acids and urinary orotate excretion were followed chronologically to evaluate urea cycle function and protein synthesis with and without this therapy. In addition to height and body weight, blood levels of proteins, lipids, growth hormone (GH), insulin-like growth factor-I (IGF-I) and IGF-binding protein -3 (IGFBP-3) were monitored. RESULTS The frequency of hyperammonemic attacks and urinary orotate excretion decreased significantly following the resumption of arginine treatment. Despite showing no marked change in body weight, height increased gradually. Extremely low plasma arginine increased to normal levels, while plasma glutamine and alanine levels decreased considerably. Except for a slight increase in high-density lipoprotein cholesterol level, blood levels of markers for nutrition did not change. In contrast, low serum IGF-I and IGFBP-3 levels increased to age-matched control levels, and normal urinary GH secretion became greater than the level observed in the controls. CONCLUSION Arginine treatment is able to reduces attacks of hyperammonemia in boys with late-onset OTCD and to increase their growth.
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Affiliation(s)
- Hironori Nagasaka
- Division of Metabolism, Chiba Children's Hospital, Chiba 266-0007, Japan.
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146
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Scaglia F, Lee B. Clinical, biochemical, and molecular spectrum of hyperargininemia due to arginase I deficiency. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2006; 142C:113-20. [PMID: 16602094 PMCID: PMC4052756 DOI: 10.1002/ajmg.c.30091] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The urea cycle consists of six consecutive enzymatic reactions that convert waste nitrogen into urea. Urea cycle disorders are a group of inborn errors of hepatic metabolism that often result in life threatening hyperammonemia and hyperglutaminemia. Deficiencies of all of the enzymes of the cycle have been described and although each specific disorder results in the accumulation of different precursors, hyperammonemia and hyperglutaminemia are common biochemical hallmarks of these disorders. Arginase is the enzyme involved in the last step of the urea cycle. It catalyzes the conversion of arginine to urea and ornithine. The latter reenters the mitochondrion to continue the cycle. Hyperargininemia is an autosomal recessive disorder caused by a defect in the arginase I enzyme. Unlike other urea cycle disorders, this condition is not generally associated with a hyperammonemic encephalopathy in the neonatal period. It typically presents later in childhood between 2 and 4 years of age with predominantly neurological features. If untreated, it progresses with gradual developmental regression. A favorable outcome can be achieved if dietary treatment and alternative pathway therapy are instituted early in the disease course. With this approach, further neurological deterioration is prevented and partial recovery of skills ensues. Early diagnosis of this disorder through newborn screening programs may lead to a better outcome. This review article summarizes the clinical characterization of this disorder; as well as its biochemical, enzymatic, and molecular features. Treatment, prenatal diagnosis and diagnosis through newborn screening are also discussed.
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Affiliation(s)
- Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine and Texas Children's Hospital, Clinical Care Center Suite 1560, 6621 Fannin Street, Houston, TX 77030, USA.
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147
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Lanpher B, Brunetti-Pierri N, Lee B. Inborn errors of metabolism: the flux from Mendelian to complex diseases. Nat Rev Genet 2006; 7:449-60. [PMID: 16708072 DOI: 10.1038/nrg1880] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Inborn errors of metabolism are characterized by dysregulation of the metabolic networks that underlie development and homeostasis, and constitute an important and expanding group of genetic disorders in humans. Diagnostic methods that are based on molecular genetic tools have a limited ability to correlate phenotypes with subtle changes in metabolic fluxes. We argue that the direct and dynamic measurement of metabolite flux will facilitate the integration of environmental, genetic and biochemical factors with phenotypic information. Ultimately, this integration will lead to new diagnostic and therapeutic approaches that are focused on the manipulation of these pathways.
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Affiliation(s)
- Brendan Lanpher
- Department of Molecular and Human Genetics, Baylor College of Medicine One Baylor Plaza, Houston, Texas 77030, USA
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148
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McBryde KD, Kershaw DB, Bunchman TE, Maxvold NJ, Mottes TA, Kudelka TL, Brophy PD. Renal replacement therapy in the treatment of confirmed or suspected inborn errors of metabolism. J Pediatr 2006; 148:770-8. [PMID: 16769384 DOI: 10.1016/j.jpeds.2006.01.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 12/07/2005] [Accepted: 01/03/2006] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Analysis of mortality and risk factors for mortality in the use of renal replacement therapy to correct metabolic disturbances associated with confirmed or suspected inborn errors of metabolism. STUDY DESIGN A retrospective review of an institutional review board-approved pediatric acute renal failure data base at the University of Michigan. Eighteen patients underwent 21 renal replacement therapy treatments for metabolic disturbances caused by urea cycle defects (n = 14), organic acidemias (n = 5), idiopathic hyperammonemia (n = 1), and Reye syndrome (n = 1). RESULTS There were 14 boys (74%) and 4 girls (26%), with a mean age and weight of 56.2 +/- 71.0 months and 18.5 +/- 19.2 kg, respectively, at the initiation of renal replacement therapy. Overall treatment mortality rate was 57.2% (12 of 21 treatments), with 11 of the 18 patients (61.1%) dying before hospital discharge. Two-year follow-up on those patients demonstrated that 5 patients (71.4%) remained alive. Initial therapy with hemodialysis was associated with improved survival. Ten treatments (47.6%) required transition to another form of renal replacement therapy to maintain ongoing metabolic control, with a mean duration of 6.1 +/- 9.8 days. Time to renal replacement therapy >24 hours was associated with an increased risk of mortality, whereas a blood pressure >5th percentile for age at the initiation of therapy and the use of anticoagulation were associated with a decreased risk of mortality. CONCLUSIONS Renal replacement therapy can correct the metabolic disturbances that accompany suspected or confirmed inborn errors of metabolism. Our experience demonstrates an approximately 60% mortality rate associated with renal replacement treatment, with more than 70% of survivors living longer than 2 years.
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Affiliation(s)
- Kevin D McBryde
- Department of Nephrology, Children's National Medical Center, Washington, DC 20010, USA.
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149
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Marini JC, Broussard SR. Hyperammonemia increases sensitivity to LPS. Mol Genet Metab 2006; 88:131-7. [PMID: 16497529 DOI: 10.1016/j.ymgme.2005.12.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 12/23/2005] [Accepted: 12/29/2005] [Indexed: 12/19/2022]
Abstract
Metabolic and cognitive alterations occur during hyperammonemia. Here, we report that chronic hyperammonemia also leads to increased sensitivity to LPS. Sparse-fur mice were challenged i.p. with LPS or saline control and then tested for motivation to investigate a novel juvenile over 24 h. Cytokine, ammonia, and urea concentration were quantified at the peak of sickness (2 h post injection). Chronic hyperammonemic Otc(spf-ash) mice displayed more pronounced and prolonged sickness behavior in response to LPS (P=0.02). LPS significantly (P<0.0001) increased plasma concentrations of TNFalpha, IL-1 beta, IL-6, IL-15, IL-9, IL-2, IL-1 alpha, IL-1 beta, Rantes, MIP1 alpha, MIP1 beta, MCP-1, KC, GM-CSF, G-CSF, Eotaxin, IL-13, and IL-12 in both wild type and Otc(spf-ash) mice. No significant genotype/treatment interactions (P>0.1) were detected for any cytokine. Adult Otc(spf-ash) mice (168+/-41 microM) had four times higher plasma ammonia compared to wild type mice (40 +/- 6 microM) (P=0.002). Two hours after LPS injection, plasma ammonia concentrations tended (P=0.08) to decrease in both wild type and Otc(spf-ash) mice. Learning and memory behaviors were assessed in mice under basal conditions to determine the impact of chronic hyperammonemia on cognition. Otc(spf-ash) mice performed significantly poorer in the two trial Y-maze (P=0.02) and the Morris water maze (P=0.001) than their littermate wild type controls. Taken together, these data indicate that chronic hyperammonemia results in impaired cognition and creates a state of LPS hypersensitivity.
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Affiliation(s)
- Juan C Marini
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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150
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Moscioni D, Morizono H, McCarter RJ, Stern A, Cabrera-Luque J, Hoang A, Sanmiguel J, Wu D, Bell P, Gao GP, Raper SE, Wilson JM, Batshaw ML. Long-term correction of ammonia metabolism and prolonged survival in ornithine transcarbamylase-deficient mice following liver-directed treatment with adeno-associated viral vectors. Mol Ther 2006; 14:25-33. [PMID: 16677864 DOI: 10.1016/j.ymthe.2006.03.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Revised: 02/12/2006] [Accepted: 03/14/2006] [Indexed: 11/25/2022] Open
Abstract
The purpose of this study was to determine the efficacy of novel recombinant adeno-associated viral (AAV) vector constructs in correcting metabolic defects in the liver in two strains of ornithine transcarbamylase (OTC)-deficient mice (spf and spf-ash). AAV vectors expressing mouse OTC were produced with capsids from AAV2 and the novel serotypes AAV7, 8, and 9. OTC-deficient mice were infused with these vectors as well as a control AAV2/8 vector expressing LacZ. In vivo activity of OTC was assessed by measuring a surrogate marker, urine orotate. The novel vectors restored orotate levels to virtually normal 15 days after infusion, and each persisted to 1 year posttreatment. Liver OTC enzyme activity in spf mice was substantially higher in animals receiving novel vectors compared to those receiving AAV2 vectors. Animals receiving novel OTC-expressing vectors lived longer than those treated with AAV2 OTC or untreated controls, and they were tolerant to a challenge with NH3 at 21 days and beyond, which caused severe morbidity in control OTC-deficient animals. Numerous mice, representative of all treatment groups followed for +250 days, were observed to have either nodules or discrete tumors in the liver, the etiology of which is the subject of a companion paper.
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Affiliation(s)
- David Moscioni
- Gene Therapy Program, Division of Medical Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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