1
|
Lung J, Sathappan S, Sabir I, Maier R. Ornithine Transcarbamylase Deficiency Presenting as Acute Encephalopathy After Strabismus Surgery. Cureus 2022; 14:e26667. [PMID: 35949797 PMCID: PMC9357435 DOI: 10.7759/cureus.26667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/08/2022] [Indexed: 11/21/2022] Open
Abstract
Acute encephalopathy with an unclear etiology is a common presentation to the hospital. We describe the case of a 50-year-old male who presented with a one-day history of slurred speech, nausea, insomnia, and altered mental status. His surgical history was notable for a strabismus surgery two days ago. He presented with elevated ammonia levels that continued to increase. Metabolic studies were suggestive of hyperammonemia secondary to ornithine transcarbamylase (OTC) deficiency triggered due to fasting prior to the strabismus surgery. OTC gene sequencing confirmed the diagnosis of OTC deficiency. We summarize the current case reports in the literature and review the treatment options for OTC deficiency. Our case occurred after a low-risk outpatient strabismus surgery and is a good example of maintaining a broad differential and revising the suspected diagnosis constantly.
Collapse
|
2
|
Kazmierski D, Sharma N, O'Leary K, Ochieng P. Valproate-induced fatal acute hyperammonaemia-related encephalopathy in late-onset ornithine transcarbamylase deficiency. BMJ Case Rep 2021; 14:14/5/e241429. [PMID: 34035022 DOI: 10.1136/bcr-2020-241429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Ornithine transcarbamylase (OTC) deficiency is a genetic disorder of the urea cycle characterised by deficiency in the enzyme OTC, resulting in an accumulation of ammonia. Valproic acid (VPA), a commonly used medication in the treatment of neurologic and psychiatric conditions, has been known to cause episodes of acute hyperammonaemia in patients with OTC deficiency. We present the case of a 29-year-old man with a long history of non-specific psychiatric disorders, who suffered from a hyperammonaemic crisis following the administration of VPA, leading to the diagnosis of OTC deficiency. The patient's hospital course was complicated by progressive cerebral oedema, which resulted in worsening encephalopathy, seizures and death. We discuss the pathophysiology of hyperammonaemia in OTC deficiency, and various management strategies, including lactulose, levocarnitine, scavenger therapy and haemodialysis.
Collapse
Affiliation(s)
- Daniel Kazmierski
- Internal Medicine, Wright Center for Graduate Medical Education, Scranton, Pennsylvania, USA
| | - Nishant Sharma
- Internal Medicine, Wright Center for Graduate Medical Education, Scranton, Pennsylvania, USA
| | - Kelly O'Leary
- Internal Medicine, Regional Hospital of Scranton, Scranton, Pennsylvania, USA
| | - Pius Ochieng
- Pulmonary & Critical Care Medicine, Geisinger Community Medical Center, Scranton, Pennsylvania, USA
| |
Collapse
|
3
|
Sen K, Anderson AA, Whitehead MT, Gropman AL. Review of Multi-Modal Imaging in Urea Cycle Disorders: The Old, the New, the Borrowed, and the Blue. Front Neurol 2021; 12:632307. [PMID: 33995244 PMCID: PMC8113618 DOI: 10.3389/fneur.2021.632307] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/26/2021] [Indexed: 12/16/2022] Open
Abstract
The urea cycle disorders (UCD) are rare genetic disorder due to a deficiency of one of six enzymes or two transport proteins that act to remove waste nitrogen in form of ammonia from the body. In this review, we focus on neuroimaging studies in OTCD and Arginase deficiency, two of the UCD we have extensively studied. Ornithine transcarbamylase deficiency (OTCD) is the most common of these, and X-linked. Hyperammonemia (HA) in OTCD is due to deficient protein handling. Cognitive impairments and neurobehavioral disorders have emerged as the major sequelae in Arginase deficiency and OTCD, especially in relation to executive function and working memory, impacting pre-frontal cortex (PFC). Clinical management focuses on neuroprotection from HA, as well as neurotoxicity from other known and yet unclassified metabolites. Prevention and mitigation of neurological injury is a major challenge and research focus. Given the impact of HA on neurocognitive function of UCD, neuroimaging modalities, especially multi-modality imaging platforms, can bring a wealth of information to understand the neurocognitive function and biomarkers. Such information can further improve clinical decision making, and result in better therapeutic interventions. In vivo investigations of the affected brain using multimodal neuroimaging combined with clinical and behavioral phenotyping hold promise. MR Spectroscopy has already proven as a tool to study biochemical aberrations such as elevated glutamine surrounding HA as well as to diagnose partial UCD. Functional Near Infrared Spectroscopy (fNIRS), which assesses local changes in cerebral hemodynamic levels of cortical regions, is emerging as a non-invasive technique and will serve as a surrogate to fMRI with better portability. Here we review two decades of our research using non-invasive imaging and how it has contributed to an understanding of the cognitive effects of this group of genetic conditions.
Collapse
Affiliation(s)
- Kuntal Sen
- Division of Neurogenetics and Neurodevelopmental Pediatrics, Department of Neurology, Children's National Hospital, George Washington University School of Medicine, Washington, DC, United States
| | - Afrouz A Anderson
- Department of Research, Focus Foundation, Crofton, MD, United States
| | - Matthew T Whitehead
- Department of Radiology, Children's National Hospital, George Washington University School of Medicine, Washington, DC, United States
| | - Andrea L Gropman
- Division of Neurogenetics and Neurodevelopmental Pediatrics, Department of Neurology, Children's National Hospital, George Washington University School of Medicine, Washington, DC, United States
| |
Collapse
|
4
|
Redant S, Empain A, Mugisha A, Kamgang P, Attou R, Honoré PM, De Bels D. Management of late onset urea cycle disorders-a remaining challenge for the intensivist? Ann Intensive Care 2021; 11:2. [PMID: 33409766 PMCID: PMC7788146 DOI: 10.1186/s13613-020-00797-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 12/26/2020] [Indexed: 12/31/2022] Open
Abstract
Background Hyperammonemia caused by a disorder of the urea cycle is a rare cause of metabolic encephalopathy that may be underdiagnosed by the adult intensivists because of its rarity. Urea cycle disorders are autosomal recessive diseases except for ornithine transcarbamylase deficiency (OTCD) that is X-linked. Optimal treatment is crucial to improve prognosis. Main body We systematically reviewed cases reported in the literature on hyperammonemia in adulthood. We used the US National Library of Medicine Pubmed search engine since 2009. The two main causes are ornithine transcarbamylase deficiency followed by type II citrullinemia. Diagnosis by the intensivist remains very challenging therefore delaying treatment and putting patients at risk of fatal cerebral edema. Treatment consists in adapted nutrition, scavenging agents and dialysis. As adults are more susceptible to hyperammonemia, emergent hemodialysis is mandatory before referral to a reference center if ammonia levels are above 200 µmol/l as the risk of cerebral edema is then above 55%. Definitive therapy in urea cycle abnormalities is liver transplantation. Conclusion Awareness of urea cycle disorders in adults intensive care units can optimize early management and accordingly dramatically improve prognosis. By preventing hyperammonemia to induce brain edema and herniation leading to death.
Collapse
Affiliation(s)
- S Redant
- Department of Intensive Care, Université Libre de Bruxelles (ULB), CHU Brugmann-Brugmann University Hospital, 4, Place Arthur Van Gehuchten, 1020, Brussels, Belgium
| | - A Empain
- Department of Metabolic Diseases, Hôpital universitaire des enfants reine Fabiola, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - A Mugisha
- Department of Intensive Care, Université Libre de Bruxelles (ULB), CHU Brugmann-Brugmann University Hospital, 4, Place Arthur Van Gehuchten, 1020, Brussels, Belgium
| | - P Kamgang
- Department of Internal Medicine, Brugmann University Hospital, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - R Attou
- Department of Intensive Care, Université Libre de Bruxelles (ULB), CHU Brugmann-Brugmann University Hospital, 4, Place Arthur Van Gehuchten, 1020, Brussels, Belgium
| | - P M Honoré
- Department of Intensive Care, Université Libre de Bruxelles (ULB), CHU Brugmann-Brugmann University Hospital, 4, Place Arthur Van Gehuchten, 1020, Brussels, Belgium.
| | - D De Bels
- Department of Intensive Care, Université Libre de Bruxelles (ULB), CHU Brugmann-Brugmann University Hospital, 4, Place Arthur Van Gehuchten, 1020, Brussels, Belgium
| |
Collapse
|
5
|
Hidaka M, Higashi E, Uwatoko T, Uwatoko K, Urashima M, Takashima H, Watanabe Y, Kitazono T, Sugimori H. Late-onset ornithine transcarbamylase deficiency: a rare cause of recurrent abnormal behavior in adults. Acute Med Surg 2020; 7:e565. [PMID: 32995020 PMCID: PMC7507316 DOI: 10.1002/ams2.565] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 07/16/2020] [Accepted: 07/31/2020] [Indexed: 11/12/2022] Open
Abstract
Background Ornithine transcarbamylase is an enzyme of the urea cycle, which produces urea from ammonia. Although ornithine transcarbamylase deficiency mainly occurs as a severe neonatal-onset disease, a late-onset form that could become symptomatic from infancy to adulthood is also known. Case presentation A 34-year-old man presented with sudden onset of abnormal behavior, lethargy, and hyperammonemia (108 µmol/L). He had recently increased daily protein intake, which suggested urea cycle disorder. After initiation of protein-restricted diet and treatment with arginine and sodium phenylbutyrate, his symptoms resolved, along with a decrease in the ammonia level. An R40H(c.119G > A) mutation in the OTC gene was identified. Conclusion Awareness of adult onset ornithine transcarbamylase deficiency in a patient with acute psychiatric symptoms due to hyperammonemia is important.
Collapse
Affiliation(s)
- Masaoki Hidaka
- Department of Cerebrovascular Medicine Stroke Center Saga Prefecture Medical Centre Koseikan Saga Japan
| | - Eiji Higashi
- Department of Cerebrovascular Medicine Stroke Center Saga Prefecture Medical Centre Koseikan Saga Japan
| | - Takeshi Uwatoko
- Department of Cerebrovascular Medicine Stroke Center Saga Prefecture Medical Centre Koseikan Saga Japan
| | - Kiku Uwatoko
- Department of Neurology Stroke Center Saga Prefecture Medical Centre Koseikan Saga Japan
| | - Mayumi Urashima
- Department of Pediatrics Saga Prefecture Medical Centre Koseikan Saga Japan
| | - Hiroshi Takashima
- Department of Neurology Stroke Center Saga Prefecture Medical Centre Koseikan Saga Japan
| | - Yoriko Watanabe
- Research Institute of Medical Mass Spectrometry Kurume University School of Medicine Kurume Japan.,Department of Pediatrics and Child Health Kurume University School of Medicine Kurume Japan
| | - Takanari Kitazono
- Department of Medicine and Clinical Science Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Hiroshi Sugimori
- Department of Cerebrovascular Medicine Stroke Center Saga Prefecture Medical Centre Koseikan Saga Japan
| |
Collapse
|
6
|
Abstract
The adult endocrinologist may be asked to consult on a patient for unexplained biochemical disturbances that could be caused by an underlying inborn error of metabolism. A genetic disorder is generally less likely to be the cause as these disorders are individually rare, however inborn errors of metabolism are collectively not infrequent and important to consider as they may be treatable and tragic outcomes avoided. Hyperammonemia or lactic acidosis are most often secondary markers of an acquired primary disease process, but they may be a clue to the presence of a genetic disorder. Herein is presented an approach to the differential diagnosis of elevated ammonia and lactate, and a brief discussion of management for when an inborn error is diagnosed.
Collapse
Affiliation(s)
- Michel Tchan
- Department of Genetic Medicine, Westmead Hospital, Westmead, NSW, Australia.
- Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
| |
Collapse
|
7
|
Sherry EB, Lee P, Choi IY. In Vivo NMR Studies of the Brain with Hereditary or Acquired Metabolic Disorders. Neurochem Res 2015; 40:2647-85. [PMID: 26610379 DOI: 10.1007/s11064-015-1772-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 11/10/2015] [Accepted: 11/12/2015] [Indexed: 01/09/2023]
Abstract
Metabolic disorders, whether hereditary or acquired, affect the brain, and abnormalities of the brain are related to cellular integrity; particularly in regard to neurons and astrocytes as well as interactions between them. Metabolic disturbances lead to alterations in cellular function as well as microscopic and macroscopic structural changes in the brain with diabetes, the most typical example of metabolic disorders, and a number of hereditary metabolic disorders. Alternatively, cellular dysfunction and degeneration of the brain lead to metabolic disturbances in hereditary neurological disorders with neurodegeneration. Nuclear magnetic resonance (NMR) techniques allow us to assess a range of pathophysiological changes of the brain in vivo. For example, magnetic resonance spectroscopy detects alterations in brain metabolism and energetics. Physiological magnetic resonance imaging (MRI) detects accompanying changes in cerebral blood flow related to neurovascular coupling. Diffusion and T1/T2-weighted MRI detect microscopic and macroscopic changes of the brain structure. This review summarizes current NMR findings of functional, physiological and biochemical alterations within a number of hereditary and acquired metabolic disorders in both animal models and humans. The global view of the impact of these metabolic disorders on the brain may be useful in identifying the unique and/or general patterns of abnormalities in the living brain related to the pathophysiology of the diseases, and identifying future fields of inquiry.
Collapse
|
8
|
Singh S, Suresh S, McClave SA, Cave M. Treating Every Needle in the Haystack. JPEN J Parenter Enteral Nutr 2014; 39:977-85. [DOI: 10.1177/0148607114546900] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 07/20/2014] [Indexed: 12/16/2022]
Affiliation(s)
- Sanjeev Singh
- Department of General Internal Medicine, Palliative Medicine and Medical Education, Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky
| | - Swetha Suresh
- Department of General Internal Medicine, Palliative Medicine and Medical Education, Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky
- Department Pediatrics, University of Louisville School of Medicine, Louisville, Kentucky
| | - Stephen A. McClave
- Department of General Internal Medicine, Palliative Medicine and Medical Education, Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky
| | - Matt Cave
- Department of General Internal Medicine, Palliative Medicine and Medical Education, Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky
- Department of Pharmacology & Toxicology, University of Louisville, Louisville, Kentucky
- Robley Rex Louisville VAMC, Louisville, Kentucky
| |
Collapse
|
9
|
Abstract
Seizures are a common paediatric problem, with inborn errors of metabolism being a rare underlying aetiology. The clinical presentation of inborn errors of metabolism is often associated with other neurological symptoms, such as hypotonia, movement disorders, and cognitive disturbances. However, the occurrence of epilepsy associated with inborn errors of metabolism represents a major challenge that needs to be identified quickly; for some cases, specific treatments are available, metabolic decompensation might be avoided, and accurate counselling can be given about recurrence risk. Some clinical presentations are more likely than others to point to an inborn error of metabolism as the cause of seizures. Knowledge of important findings at examination, and appropriate biochemical investigation of children with seizures of uncertain cause, can aid the diagnosis of an inborn error of metabolism and ascertain whether or not the seizures are amenable to specific metabolic treatment.
Collapse
Affiliation(s)
- Olivier Dulac
- Paris Descartes University, Inserm U1129, Paris, France; CEA, Gif-sur-Yvette, France; Department of Paediatric Neurology, Hôpital Necker-Enfants Malades, AP-HP, Paris, France.
| | - Barbara Plecko
- Department of Child Neurology, University Children's Hospital, University of Zurich, Switzerland
| | | | - Nicole I Wolf
- Department of Child Neurology, VU University Medical Center, Amsterdam, Netherlands; Neuroscience Campus Amsterdam, Amsterdam, Netherlands
| |
Collapse
|
10
|
Abstract
Inborn errors of metabolism (IEM) are a phenotypically and genetically heterogeneous group of disorders caused by a defect in a metabolic pathway, leading to malfunctioning metabolism and/or the accumulation of toxic intermediate metabolites. To date, more than 1000 different IEM have been identified. While individually rare, the cumulative incidence has been shown to be upwards of 1 in 800. Clinical presentations are protean, complicating diagnostic pathways. IEM are present in all ethnic groups and across every age. Some IEM are amenable to treatment, with promising outcomes. However, high clinical suspicion alone is not sufficient to reduce morbidities and mortalities. In the last decade, due to the advent of tandem mass spectrometry, expanded newborn screening (NBS) has become a mandatory public health strategy in most developed and developing countries. The technology allows inexpensive simultaneous detection of more than 30 different metabolic disorders in one single blood spot specimen at a cost of about USD 10 per baby, with commendable analytical accuracy and precision. The sensitivity and specificity of this method can be up to 99% and 99.995%, respectively, for most amino acid disorders, organic acidemias, and fatty acid oxidation defects. Cost-effectiveness studies have confirmed that the savings achieved through the use of expanded NBS programs are significantly greater than the costs of implementation. The adverse effects of false positive results are negligible in view of the economic health benefits generated by expanded NBS and these could be minimized through increased education, better communication, and improved technologies. Local screening agencies should be given the autonomy to develop their screening programs in order to keep pace with international advancements. The development of biochemical genetics is closely linked with expanded NBS. With ongoing advancements in nanotechnology and molecular genomics, the field of biochemical genetics is still expanding rapidly. The potential of tandem mass spectrometry is extending to cover more disorders. Indeed, the use of genetic markers in T-cell receptor excision circles for severe combined immunodeficiency is one promising example. NBS represents the highest volume of genetic testing. It is more than a test and it warrants systematic healthcare service delivery across the pre-analytical, analytical, and post-analytical phases. There should be a comprehensive reporting system entailing genetic counselling as well as short-term and long-term follow-up. It is essential to integrate existing clinical IEM services with the expanded NBS program to enable close communication between the laboratory, clinicians, and allied health parties. In this review, we will discuss the history of IEM, its clinical presentations in children and adult patients, and its incidence among different ethnicities; the history and recent expansion of NBS, its cost-effectiveness, associated pros and cons, and the ethical issues that can arise; the analytical aspects of tandem mass spectrometry and post-analytical perspectives regarding result interpretation.
Collapse
Affiliation(s)
- Chloe Miu Mak
- Chemical Pathology Laboratory, Department of Pathology, Princess Margaret Hospital , Hong Kong, SAR , China and
| | | | | | | |
Collapse
|
11
|
Bergmann KR, McCabe J, Smith TR, Guillaume DJ, Sarafoglou K, Gupta S. Late-onset ornithine transcarbamylase deficiency: treatment and outcome of hyperammonemic crisis. Pediatrics 2014; 133:e1072-6. [PMID: 24616362 DOI: 10.1542/peds.2013-1324] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Hyperammonemic crises in ornithine transcarbamylase deficiency (OTC) can be associated with devastating cerebral edema resulting in severe long-term neurologic impairment and death. We present an 8-year-old boy who had late-onset OTC deficiency in which early and aggressive management of hyperammonemia and associated cerebral edema, including therapeutic hypothermia and barbiturate-induced coma, resulted in favorable neurologic outcome. Our patient presented with vomiting and altered mental status, and was found to have a significantly elevated serum ammonia level of 1561 μmol/L. Hyperammonemia was managed with hemodialysis, 10% sodium phenylacetate, 10% sodium benzoate, L-arginine, intravenous 10% dextrose, intralipids, and protein restriction. He developed significant cerebral edema with intracranial pressures >20 mm Hg, requiring treatment with 3% saline and mannitol. Despite this treatment our patient continued to have elevated intracranial pressures, which were treated aggressively with non-conventional modalities including therapeutic hypothermia, barbiturate-induced coma, and external ventricular drainage. This therapy resulted in stabilization of hyperammonemia and resolution of cerebral edema. Molecular testing later revealed a hemizygous mutation within the OTC gene. Neuropsychological testing 1 year after discharge showed normal intelligence with no visual-motor deficits, minor deficits in working memory and processing speed, and slightly below average processing speed and executive functioning.
Collapse
|
12
|
|
13
|
Abstract
Epilepsies associated with inborn errors of metabolism (IEM) represent a major challenge. Seizures rarely dominate the clinical presentation, which is more frequently associated with other neurological symptoms, such as hypotonia and/or cognitive disturbances. Although epilepsy in IEM can be classified in various ways according to pathogenesis, age of onset, or electroclinical presentation, the most pragmatic approach is determined by whether they are accessible to specific treatment or not. The main potentially treatable causes comprise vitamin B6 (pyridoxine deficiency), biotine, and GLUT1 deficiency (GLUT1DS) syndromes. Folinic acid-dependent seizures are allelic with pyridoxine dependency. Incompletely treatable IEMs include pyridoxal phosphate, serine, and creatine deficiencies. The main IEMs that present with epilepsy but offer no specific treatment are nonketotic hyperglycinemia, mitochondrial disorders, sulfite oxidase deficiency, ceroid-lipofuscinosis, Menkes disease, and peroxisomal disorders.
Collapse
Affiliation(s)
- Nadia Bahi-Buisson
- Department of Pediatric Neurology, Université Paris Descartes; Imaging Institute; INSERM U781, Paris, France.
| | | |
Collapse
|
14
|
Aires CCP, van Cruchten A, Ijlst L, de Almeida IT, Duran M, Wanders RJA, Silva MFB. New insights on the mechanisms of valproate-induced hyperammonemia: inhibition of hepatic N-acetylglutamate synthase activity by valproyl-CoA. J Hepatol 2011; 55:426-34. [PMID: 21147182 DOI: 10.1016/j.jhep.2010.11.031] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 10/22/2010] [Accepted: 11/08/2010] [Indexed: 12/04/2022]
Abstract
BACKGROUND & AIMS Hyperammonemia is a frequent side-effect of valproic acid (VPA) therapy, which points to an imbalance between ammoniagenesis and ammonia disposal via the urea cycle. The impairment of this liver-specific metabolic pathway induced either by primary genetic defects or by secondary causes, namely associated with drugs administration, may result in accumulation of ammonia. To elucidate the mechanisms which underlie VPA-induced hyperammonemia, the aim of this study was to evaluate the effect of both VPA and its reactive intermediate, valproyl-CoA (VP-CoA), on the synthesis of N-acetylglutamate (NAG), a prime metabolite activator of the urea cycle. METHODS The amount of NAG in livers of rats treated with VPA was quantified by HPLC-MS/MS. The NAG synthase (NAGS) activity was evaluated in vitro in rat liver mitochondria, and the effect of both VPA and VP-CoA was characterized. RESULTS The present results clearly show that VP-CoA is a stronger inhibitor of NAGS activity in vitro than the parent drug VPA. The hepatic levels of NAG were significantly reduced in VPA-treated rats as compared with control tissues. CONCLUSIONS These data strongly suggest that the hyperammonemia observed in patients under VPA treatment may result from a direct inhibition of the NAGS activity by VP-CoA. The subsequent reduced availability of NAG will impair the flux through the urea cycle and compromise the major role of this pathway in ammonia detoxification.
Collapse
Affiliation(s)
- Cátia C P Aires
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
15
|
Ritter E, Husain RA, Hinderhofer K, Prell T, Fricke H, Scholl S, Hochhaus A, La Rosée P. Ornithine transcarbamylase (OTC) deficiency based on a hemizygous p.R277W mutation causing life-threatening hyperammonemic crisis during treatment for Hodgkin’s lymphoma. Ann Hematol 2011; 90:857-9. [DOI: 10.1007/s00277-010-1106-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
16
|
Abstract
The clinical application of pharmacogenetics has been well accepted by some medical specialties, but not all. The aim of this review is to discuss the current use of pharmacogenetics in reproductive and perinatal medicine and to highlight areas where pharmacogenetics may be able to help in the future to predict response to medicines in terms of efficacy and safety. This applies to drugs that are specific to pregnancy and reproduction, as well as drugs prescribed for the treatment of medical disorders in pregnancy. Our review points out the need for well-designed clinical studies on the efficacy and safety of medicines used in women of childbearing age in order to define the additional utility provided by pharmacogenetic testing.
Collapse
Affiliation(s)
- Ana Alfirevic
- Department of Pharmacology & Therapeutics, Sherrington Building, Ashton Street, University of Liverpool, Liverpool, Merseyside, L69 3GE, UK
| | | | - Munir Pirmohamed
- Department of Pharmacology & Therapeutics, Sherrington Building, Ashton Street, University of Liverpool, Liverpool, Merseyside, L69 3GE, UK
| |
Collapse
|
17
|
Garcia M, Huppertz HJ, Ziyeh S, Buechert M, Schumacher M, Mader I. Valproate-induced metabolic changes in patients with epilepsy: Assessment with1H-MRS. Epilepsia 2009; 50:486-92. [DOI: 10.1111/j.1528-1167.2008.01801.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
18
|
Katiyar A, Aaron C. Case files of the Children's Hospital of Michigan Regional Poison Control Center: the use of carnitine for the management of acute valproic acid toxicity. J Med Toxicol 2007; 3:129-38. [PMID: 18072149 DOI: 10.1007/BF03160923] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
|
19
|
Nott L, Price TJ, Pittman K, Patterson K, Fletcher J. Hyperammonemia encephalopathy: an important cause of neurological deterioration following chemotherapy. Leuk Lymphoma 2007; 48:1702-11. [PMID: 17786705 DOI: 10.1080/10428190701509822] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Idiopathic hyperammonemic encephalopathy is an uncommon but frequently fatal complication of chemotherapy. It is characterised by abrupt alteration in mental status with markedly elevated plasma ammonia levels in the absence of obvious liver disease or any other identifiable cause, and frequently results in intractable coma and death. It usually occurs in patients with haematologic malignancies during the period of neutropenia following cytoreductive therapy or bone marrow transplantation, and in solid organ malignancies treated with 5-fluorouracil. Although the aetiology of this syndrome is yet to be determined, it appears to be multi-factorial in nature. Optimal management remains to be formally established, and the critical step is increased awareness of the syndrome by measurement of plasma ammonium levels in patients with neurological symptoms, leading to early diagnosis and the prompt implementation of therapy.
Collapse
Affiliation(s)
- Louise Nott
- Department of Oncology, The Queen Elizabeth Hospital, Woodville, Australia
| | | | | | | | | |
Collapse
|
20
|
Chiong MA, Bennetts BH, Strasser SI, Wilcken B. Fatal late-onset ornithine transcarbamylase deficiency after coronary artery bypass surgery. Med J Aust 2007; 186:418-9. [PMID: 17437397 DOI: 10.5694/j.1326-5377.2007.tb00976.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2006] [Accepted: 01/29/2007] [Indexed: 11/17/2022]
Affiliation(s)
- Mary Anne Chiong
- Western Sydney Genetics Program, The Children's Hospital at Westmead, Sydney, NSW
| | | | | | | |
Collapse
|