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Sen K, Whitehead M, Castillo Pinto C, Caldovic L, Gropman A. Fifteen years of urea cycle disorders brain research: Looking back, looking forward. Anal Biochem 2022; 636:114343. [PMID: 34637785 PMCID: PMC8671367 DOI: 10.1016/j.ab.2021.114343] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/13/2021] [Accepted: 08/17/2021] [Indexed: 01/03/2023]
Abstract
Urea cycle disorders (UCD) are inherited diseases resulting from deficiency in one of six enzymes or two carriers that are required to remove ammonia from the body. UCD may be associated with neurological damage encompassing a spectrum from asymptomatic/mild to severe encephalopathy, which results in most cases from Hyperammonemia (HA) and elevation of other neurotoxic intermediates of metabolism. Electroencephalography (EEG), Magnetic resonance imaging (MRI) and Proton Magnetic resonance spectroscopy (MRS) are noninvasive measures of brain function and structure that can be used during HA to guide management and provide prognostic information, in addition to being research tools to understand the pathophysiology of UCD associated brain injury. The Urea Cycle Rare disorders Consortium (UCDC) has been invested in research to understand the immediate and downstream effects of hyperammonemia (HA) on brain using electroencephalogram (EEG) and multimodal brain MRI to establish early patterns of brain injury and to track recovery and prognosis. This review highlights the evolving knowledge about the impact of UCD and HA in particular on neurological injury and recovery and use of EEG and MRI to study and evaluate prognostic factors for risk and recovery. It recognizes the work of others and discusses the UCDC's prior work and future research priorities.
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Affiliation(s)
- Kuntal Sen
- Division of Neurogenetics and Neurodevelopmental Pediatrics, Children's National Hospital, Washington D.C., United States
| | - Matthew Whitehead
- Division of Radiology, Children's National Hospital, Washington D.C., United States
| | | | - Ljubica Caldovic
- Childrens' Research Institute, Children's National Hospital, Washington D.C., United States
| | - Andrea Gropman
- Division of Neurogenetics and Neurodevelopmental Pediatrics, Children's National Hospital, Washington D.C., United States.
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Toquet S, Spodenkiewicz M, Douillard C, Maillot F, Arnoux JB, Damaj L, Odent S, Moreau C, Redonnet-Vernhet I, Mesli S, Servais A, Noel E, Charriere S, Rigalleau V, Lavigne C, Kaphan E, Roubertie A, Besson G, Bigot A, Servettaz A, Mochel F, Garnotel R. Adult-onset diagnosis of urea cycle disorders: Results of a French cohort of 71 patients. J Inherit Metab Dis 2021; 44:1199-1214. [PMID: 34014557 DOI: 10.1002/jimd.12403] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 12/19/2022]
Abstract
Urea cycle disorders (UCD) are rare diseases that usually affect neonates or young children. During decompensations, hyperammonemia is neurotoxic, leading to severe symptoms and even coma and death if not treated rapidly. The aim was to describe a cohort of patients with adult onset of UCDs in a multicentric, retrospective and descriptive study of French adult patients with a diagnosis after 16 years of age of UCDs due to a deficiency in one of the 6 enzymes (arginase, ASL, ASS, CPS1, NAGS, OTC) or the two transporters (ORNT1 or citrin). Seventy-one patients were included (68% female, 32% male). The diagnosis was made in the context of (a) a metabolic decompensation (42%), (b) family history (55%), or (c) chronic symptoms (3%). The median age at diagnosis was 33 years (range 16-86). Eighty-nine percent of patients were diagnosed with OTC deficiency, 7% CPS1 deficiency, 3% HHH syndrome and 1% argininosuccinic aciduria. For those diagnosed during decompensations (including 23 OTC cases, mostly female), 89% required an admission in intensive care units. Seven deaths were attributed to UCD-6 decompensations and 1 epilepsy secondary to inaugural decompensation. This is the largest cohort of UCDs diagnosed in adulthood, which confirms the triad of neurological, gastrointestinal and psychiatric symptoms during hyperammonemic decompensations. We stress that females with OTC deficiency can be symptomatic. With 10% of deaths in this cohort, UCDs in adults remain a life-threatening condition. Physicians working in adult care must be aware of late-onset presentations given the implications for patients and their families.
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Affiliation(s)
- Ségolène Toquet
- Service de Médecine Interne, Hôpital Robert Debré, CHU Reims, France
| | | | - Claire Douillard
- Service d'Endocrinologie et Métabolismes, Hôpital Claude Huriez, Centre de Référence des Maladies Héréditaires du métabolisme, CHU Lille, France
| | - François Maillot
- Service de Médecine Interne, Hôpital Bretonneau, CHRU de Tours, France
| | - Jean-Baptiste Arnoux
- Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Necker-Enfants Malades, CHU Paris, France
| | - Lena Damaj
- Service de Pédiatrie, CHU Hôpital Sud, Rennes, France
| | - Sylvie Odent
- Service de Génétique Clinique, CHU Hôpital Sud, Rennes, France
| | - Caroline Moreau
- Service de Biochimie et Toxicologie, CHU Pontchaillou, Rennes, France
| | | | - Samir Mesli
- Laboratoire de Biochimie, Hôpital Pellegrin, CHU Bordeaux, France
| | - Aude Servais
- Service de Néphrologie adulte, Hôpital Necker-Enfants Malades, CHU Paris, France
| | - Esther Noel
- Service de Médecine Interne, Hôpital Universitaire de Strasbourg, CHRU Strasbourg, France
| | - Sybill Charriere
- Fédération d'endocrinologie, maladies métaboliques, diabète et nutrition, Hôpital Louis Pradel, Centre de Référence des Maladies Héréditaires du Métabolisme, Bron, France
| | | | | | - Elsa Kaphan
- Pôle de Neurosciences Cliniques, CHU Timone, AP-HM, Marseille, France
| | - Agathe Roubertie
- Département de neuropédiatrie, Hôpital Gui de Chauliac, CHU Montpellier, France
| | | | - Adrien Bigot
- Service de Médecine Interne, Hôpital Bretonneau, CHRU de Tours, France
| | - Amélie Servettaz
- Service de Médecine Interne, Hôpital Robert Debré, CHU Reims, France
| | - Fanny Mochel
- Département de génétique, Hôpital Pitié-Salpêtrière, CHU Paris, France
| | - Roselyne Garnotel
- Laboratoire de Biochimie-Pharmacologie-Toxicologie, CHU Reims, France
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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: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [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.
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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
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Bigot A, Brunault P, Lavigne C, Feillet F, Odent S, Kaphan E, Thauvin C, Leguy V, Broué P, Tchan MC, Maillot F. Psychiatric adult-onset of urea cycle disorders: A case-series. Mol Genet Metab Rep 2017; 12:103-109. [PMID: 28725569 PMCID: PMC5502717 DOI: 10.1016/j.ymgmr.2017.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/02/2017] [Accepted: 07/02/2017] [Indexed: 12/30/2022] Open
Abstract
Adult onset urea cycle disorders (UCD) may present with psychiatric symptoms, occasionally as the initial presentation. We aimed to describe the characteristics of patients presenting with a psychiatric adult-onset of UCDs, to discuss which signs could suggest this diagnosis in such a situation, and to determine which tests should be conducted. A survey of psychiatric symptoms occurring in teenagers or adults with UCD was conducted in 2010 among clinicians involved in the French society for the study of inborn errors of metabolism (SFEIM). Fourteen patients from 14 to 57 years old were reported. Agitation was reported in 10 cases, perseveration in 5, delirium in 4, and disinhibition in 3 cases. Three patients had pre-existing psychiatric symptoms. All patients had neurological symptoms associated with psychiatric symptoms, such as ataxia or dysmetria, psychomotor slowing, seizures, or hallucinations. Fluctuations of consciousness and coma were reported in 9 cases. Digestive symptoms were reported in 7 cases. 9 patients had a personal history suggestive of UCD. The differential diagnoses most frequently considered were exogenous intoxication, non-convulsive status epilepticus, and meningoencephalitis. Hyperammonemia (180-600 μmol/L) was found in all patients. The outcome was severe: mechanical ventilation was required in 10 patients, 5 patients died, and only 4 patients survived without sequelae. Adult onset UCDs can present with predominant psychiatric symptoms, associated with neurological involvement. These patients, as well as patients presenting with a suspicion of intoxication, must have UCD considered and ammonia measured without delay.
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Affiliation(s)
- Adrien Bigot
- CHRU de Tours, Médecine interne, Tours, France
- CHRU de Toulouse, Service de pédiatrie, Toulouse, France
- Genetic Medicine, Westmead Hospital, NSW, Australia
| | - Paul Brunault
- CHRU de Tours, Clinique Psychiatrique Universitaire, Tours, France
- CHRU de Tours, Équipe de Liaison et de Soins en Addictologie, Tours, France
| | | | - François Feillet
- CHRU de Nancy, Centre de références des maladies héréditaires du métabolisme, Nancy, France
| | - Sylvie Odent
- CHRU de Rennes, Service de génétique, Rennes, France
| | - Elsa Kaphan
- CHRU de Marseille, Service de neurologie, La Timone, Marseille, France
| | | | - Vanessa Leguy
- CHRU de Dijon, Service de Médecine Interne, Dijon, France
| | - Pierre Broué
- CHRU de Toulouse, Service de pédiatrie, Toulouse, France
| | | | - François Maillot
- CHRU de Tours, Médecine interne, Tours, France
- Université François-Rabelais, INSERM 1069, Tours, France
- Corresponding author at: Service de Médecine Interne, Hopital Bretonneau, 2bd Tonnellé, 37044 Tours CEDEX 9, France.Service de Médecine InterneHopital Bretonneau2bd TonnelléTours CEDEX 937044France
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Cavicchi C, Donati M, Parini R, Rigoldi M, Bernardi M, Orfei F, Gentiloni Silveri N, Colasante A, Funghini S, Catarzi S, Pasquini E, la Marca G, Mooney S, Guerrini R, Morrone A. Sudden unexpected fatal encephalopathy in adults with OTC gene mutations-Clues for early diagnosis and timely treatment. Orphanet J Rare Dis 2014; 9:105. [PMID: 25026867 PMCID: PMC4304088 DOI: 10.1186/s13023-014-0105-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 06/27/2014] [Indexed: 12/30/2022] Open
Abstract
Background X-linked Ornithine Transcarbamylase deficiency (OTCD) is often unrecognized in adults, as clinical manifestations are non-specific, often episodic and unmasked by precipitants, and laboratory findings can be normal outside the acute phase. It may thus be associated with significant mortality if not promptly recognized and treated. The aim of this study was to provide clues for recognition of OTCD in adults and analyze the environmental factors that, interacting with OTC gene mutations, might have triggered acute clinical manifestations. Methods We carried out a clinical, biochemical and molecular study on five unrelated adult patients (one female and four males) with late onset OTCD, who presented to the Emergency Department (ED) with initial fatal encephalopathy. The molecular study consisted of OTC gene sequencing in the probands and family members and in silico characterization of the newly detected mutations. Results We identified two new, c.119G>T (p.Arg40Leu) and c.314G>A (p.Gly105Glu), and three known OTC mutations. Both new mutations were predicted to cause a structural destabilization, correlating with late onset OTCD. We also identified, among the family members, 8 heterozygous females and 2 hemizygous asymptomatic males. Patients' histories revealed potential environmental triggering factors, including steroid treatment, chemotherapy, diet changes and hormone therapy for in vitro fertilization. Conclusions This report raises awareness of the ED medical staff in considering OTCD in the differential diagnosis of sudden neurological and behavioural disorders associated with hyperammonemia at any age and in both genders. It also widens the knowledge about combined effect of genetic and environmental factors in determining the phenotypic expression of OTCD.
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Mukhtar A, Dabbous H, El Sayed R, Aboulfetouh F, Bahaa M, Abdelaal A, Fathy M, El-Meteini M. A novel mutation of the ornithine transcarbamylase gene leading to fatal hyperammonemia in a liver transplant recipient. Am J Transplant 2013; 13:1084-1087. [PMID: 23551631 DOI: 10.1111/ajt.12146] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Revised: 11/22/2012] [Accepted: 12/10/2012] [Indexed: 02/06/2023]
Abstract
Ornithine transcarbamylase (OTC) deficiency (OTCD) is an X-linked urea cycle disorder. Being an X-linked disease, the onset and severity of the disease may vary among female carriers. Some of them start to develop the disease early in life, whereas others remain asymptomatic throughout their lives. Our patient was a 42-year-old man who developed severe hyperammonemia and fatal brain edema after receiving a right lobe graft from an asymptomatic female living donor with unrecognized OTCD. The donor developed hyperammonemia and disturbed level of consciousness that was managed successfully by hemodialysis. Molecular testing of the OTC gene in the donor revealed a heterozygous nonsense mutation (c.429T>A) in exon 5.
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Affiliation(s)
- A Mukhtar
- Department of Anesthesia and Critical Care, Cairo University, Egypt
| | - H Dabbous
- Ain-Shams Center for Organ Transplant (ASCOT), Ain Shams University, Cairo, Egypt
| | - R El Sayed
- Department of Clinical and Chemical Pathology, Cairo University, Egypt
| | - F Aboulfetouh
- Department of Anesthesia and Critical Care, Cairo University, Egypt
| | - M Bahaa
- Ain-Shams Center for Organ Transplant (ASCOT), Ain Shams University, Cairo, Egypt
| | - A Abdelaal
- Ain-Shams Center for Organ Transplant (ASCOT), Ain Shams University, Cairo, Egypt
| | - M Fathy
- Ain-Shams Center for Organ Transplant (ASCOT), Ain Shams University, Cairo, Egypt
| | - M El-Meteini
- Ain-Shams Center for Organ Transplant (ASCOT), Ain Shams University, Cairo, Egypt
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Wakiya T, Sanada Y, Urahashi T, Ihara Y, Yamada N, Okada N, Egami S, Sakamoto K, Murayama K, Hakamada K, Yasuda Y, Mizuta K. Living donor liver transplantation from an asymptomatic mother who was a carrier for ornithine transcarbamylase deficiency. Pediatr Transplant 2012; 16:E196-200. [PMID: 22583334 DOI: 10.1111/j.1399-3046.2012.01716.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Liver transplantation (LT) has been adopted as a radical treatment for ornithine transcarbamylase deficiency (OTCD), yielding favorable outcomes. Despite the fact that it is an inheritable disease, a blood relative who is heterozygous for the disorder must sometimes be used as a liver donor for living donor LT. There is ongoing discussion regarding the use of heterozygous donors, however, to our knowledge, no cases where donation was determined based on the Ornithine transcarbamylase (OTC) activity before LT have been reported. Between May 2001 and April 2011, 17 patients were indicated for living donor LT because of OTCD at our facility. There were three cases with heterozygous donor candidate (17.6%). All heterozygous candidates underwent a liver biopsy to measure their OTC activity before LT and made efforts to secure the safety of the both donor and recipient. Two of 3 candidates had headaches sometimes, and their activity was less than 40%, and thus they were not employed as the donor. One candidate with 104.4% activity was employed, yielding favorable outcomes. Our current experience supported the effectiveness of our donation criteria, however it is necessary to collect sufficient data on a large number of patients to confirm the safety of the procedure.
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Affiliation(s)
- T Wakiya
- Department of Transplant Surgery, Jichi Medical University, Tochigi, Japan.
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Jörck C, Kiess W, Weigel JFW, Mütze U, Bierbach U, Beblo S. Transient hyperammonemia due to L-asparaginase therapy in children with acute lymphoblastic leukemia or non-Hodgkin lymphoma. Pediatr Hematol Oncol 2011; 28:3-9. [PMID: 20615069 DOI: 10.3109/08880018.2010.484852] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The standard treatment protocol for acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL) in childhood includes intravenous therapy with asparaginase (Asp), which may cause hyperammonemia. In this study, all patients receiving asparaginase therapy at the Hospital for Children and Adolescents of the University of Leipzig between January 2002 and December 2007 were reviewed for the occurrence of hyperammonemia. Fifty-four patients were identified (22 girls, 32 boys; mean age 5.8 years). Blood ammonia concentrations were determined in 4 patients due to suspicious clinical signs. All showed hyperammonemia with NH(3) concentrations between 260 and 700 μmol/L. They received specific acute detoxification therapy consisting in protein restriction, administration of benzoic acid, glucose/insulin. All 4 recovered completely. All patients receiving therapeutic regimes that include asparaginase (Asp) should be monitored for the development of transient hyperammonemia.
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Affiliation(s)
- C Jörck
- Hospital for Children and Adolescents, University of Leipzig, Leipzig, Germany
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Brajon D, Carassou P, Pruna L, Feillet F, Kaminsky P. [Ornithine transcarbamylase deficiency in adult]. Rev Med Interne 2010; 31:709-11. [PMID: 20570026 DOI: 10.1016/j.revmed.2010.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 01/11/2010] [Accepted: 02/06/2010] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Ornithine transcarbamylase (OTC) deficiency is a X-linked inherited disorder characterized by hyperammoniemic encephalopathy in male neonates. However, there is an increased evidence of late-onset disease, including in adults. CASE REPORTS A 23-year-old woman presented with vomiting, somnolence, confusion and hyperammonemia. Familial history revealed OTC deficiency in three brothers and one sister, but urinary orotic acid level was normal at birth in the reported patient who therefore was considered as mutation-free. The mother was asymptomatic but had cognitive defect and moderate mental deficiency. Molecular biology demonstrated that both our patient and her mother were heterozygous for complete OCT deletion. CONCLUSION OCT deficiency could be diagnosed in adult patients at any age and clinical features are various, including hyperammonemic encephalopathy, psychiatric disorders or mental deficiency.
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Affiliation(s)
- D Brajon
- Médecine interne orientée vers les maladies orphelines et systémiques, Tour Drouet, hôpitaux de Brabois, CHU de Nancy, 54511 Vandœuvre cedex, France
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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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11
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Acute hyperammonemic encephalopathy in adult onset ornithine transcarbamylase deficiency. Intensive Care Med 2008; 34:1922-4. [PMID: 18651132 DOI: 10.1007/s00134-008-1217-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Accepted: 06/19/2008] [Indexed: 02/06/2023]
Abstract
OBJECTIVES To report the clinical manifestations of acute hyperammonemic encephalopathy in adult onset ornithine transcarbamylase deficiency (OTCD). DESIGN Case report. SETTING Intensive care unit of a tertiary medical centre. PATIENT A 48-year-old Caucasian male body builder who developed acute loss of consciousness after a febrile illness. INTERVENTIONS The patient was immediately started on hemodia-filtration, protein elimination and ammonia scavenging medications. MEASUREMENTS AND RESULTS Serum ammonium was elevated and plasma and urine amino acids had a pattern indicative of a urea cycle defect. DNA studies revealed a mutation of the urea cycle enzyme, ornithine transcarbamylase. The encephalopathy resolved and the patient slowly recovered though with some cognitive impairment. CONCLUSIONS Adult presentation of OTCD is rare and the mortality and morbidity rates are high. However, survival is possible with rapid correction of hyperammonemia. As the clinical manifestations are non-specific, a high index of suspicion is necessary for the correct diagnosis and management.
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Abstract
INTRODUCTION Urea cycle disorders (UCD) usually present after 24 h to 48 h of life with failure to thrive, lethargy and coma leading to death, but milder forms may occur from infancy to adulthood. STATE OF THE ART Survival of children with UCD has significantly improved and the need for transitional care to adulthood has emerged. Adult onset UCD present with chronic or acute neurological, psychiatric and digestive symptoms associated with protein avoidance. Ornithine transcarbamylase (OTC) deficiency, which is inherited as an X-linked disorder, is the most well-described UCD in adults. Acute decompensations associate the triad of encephalopathy, respiratory alkalosis and hyperammonemia. Acute encephalopathy is characterized by brain edema, which is life-threatening without treatment. Specific urea cycle enzyme deficiency can be suspected in the presence of abnormal plasma amino acids concentrations and urinary excretion of orotic acid. A measurement enzyme activity in appropriate tissue, or DNA analysis if available, is required for diagnosis. Treatment requires restriction of dietary protein intake and the use of alternative pathways of waste nitrogen excretion with sodium benzoate and sodium phenylbutyrate. Patients with acute forms may need hemodialysis or hemodiafiltration. Therapeutic goals for OTC deficiency are to maintain plasma ammonia<80 micromol/L, plasma glutamine<1,000 micromol/L, argininemia 80-150 micromol/L and branched chain amino acids within the normal range, in order to prevent episodes of potentially lethal acute hyperammonemia. CONCLUSION Potentially fatal acute hyperammonemia may occur in male or female patients at any age. Ammonia should be measured promptly in case of acute neurological and psychiatric symptoms or coma.
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Affiliation(s)
- F Maillot
- Service de Médecine Interne et Nutrition, CHRU,Tours, France.
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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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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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