1
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Singh RH, Bourdages MH, Kurtz A, MacLoed E, Norman C, Ratko S, van Calcar SC, Kenneson A. The efficacy of Carbamylglutamate impacts the nutritional management of patients with N-Acetylglutamate synthase deficiency. Orphanet J Rare Dis 2024; 19:168. [PMID: 38637895 PMCID: PMC11027358 DOI: 10.1186/s13023-024-03167-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 03/30/2024] [Indexed: 04/20/2024] Open
Abstract
BACKGROUND The autosomal recessive disorder N-acetylglutamate synthase (NAGS) deficiency is the rarest defect of the urea cycle, with an incidence of less than one in 2,000,000 live births. Hyperammonemic crises can be avoided in individuals with NAGS deficiency by the administration of carbamylglutamate (also known as carglumic acid), which activates carbamoyl phosphatase synthetase 1 (CPS1). The aim of this case series was to introduce additional cases of NAGS deficiency to the literature as well as to assess the role of nutrition management in conjunction with carbamylglutamate therapy across new and existing cases. METHODS We conducted retrospective chart reviews of seven cases of NAGS deficiency in the US and Canada, focusing on presentation, diagnosis, medication management, nutrition management, and outcomes. RESULTS Five new and two previously published cases were included. Presenting symptoms were consistent with previous reports. Diagnostic confirmation via molecular testing varied in protocol across cases, with consecutive single gene tests leading to long delays in diagnosis in some cases. All patients responded well to carbamylglutamate therapy, as indicated by normalization of plasma ammonia and citrulline, as well as urine orotic acid in patients with abnormal levels at baseline. Although protein restriction was not prescribed in any cases after carbamylglutamate initiation, two patients continued to self-restrict protein intake. One patient experienced two episodes of hyperammonemia that resulted in poor long-term outcomes. Both episodes occurred after a disruption in access to carbamylglutamate, once due to insurance prior authorization requirements and language barriers and once due to seizure activity limiting the family's ability to administer carbamylglutamate. CONCLUSIONS Follow-up of patients with NAGS deficiency should include plans for illness and for disruption of carbamylglutamate access, including nutrition management strategies such as protein restriction. Carbamylglutamate can help patients with NAGS deficiency to liberalize their diets, but the maximum safe level of protein intake to prevent hyperammonemia is not yet known. Patients using this medication should still monitor their diet closely and be prepared for any disruptions in medication access, which might require immediate dietary adjustments or medical intervention to prevent hyperammonemia.
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Affiliation(s)
- Rani H Singh
- Emory University School of Medicine, 101 Woodruff Circle, 7th Floor Suite 7130, 30322, Atlanta, GA, USA.
| | | | | | - Erin MacLoed
- Children's National Medical Center, Washington, DC, USA
| | | | | | | | - Aileen Kenneson
- Emory University School of Medicine, 101 Woodruff Circle, 7th Floor Suite 7130, 30322, Atlanta, GA, USA
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2
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Fátima Lopes F, Sitta A, de Moura Coelho D, Schmitt Ribas G, Lamberty Faverzani J, Gomes Dos Reis B, Wajner M, Vargas CR. Clinical findings of patients with hyperammonemia affected by urea cycle disorders with hepatic encephalopathy. Int J Dev Neurosci 2022; 82:772-788. [PMID: 36129623 DOI: 10.1002/jdn.10229] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 08/21/2022] [Accepted: 09/15/2022] [Indexed: 11/10/2022] Open
Abstract
Urea Cycle Disorders (UCD) are a group of genetic diseases caused by deficiencies in the enzymes and transporters involved in the urea cycle. The impairment of the cycle results in ammonia accumulation, leading to neurological dysfunctions and poor outcomes to affected patients. The aim of this study is to investigate and describe UCD patients principal clinical and biochemical presentations to support professionals on urgent diagnosis and quick management, aiming better outcomes for patients. We explored medical records of thirty patients diagnosed in a referral center from Brazil to delineate UCD clinical and biochemical profile. Patients demonstrated a range of signs and symptoms, such as altered levels of consciousness, acute encephalopathy, seizures, progressive loss of appetite, vomiting, coma, and respiratory distress, in most cases combined with high levels of ammonia, which is an immediate biomarker, leading to an UCD suspicion. The most prevalent UCD detected were ornithine transcarbamylase deficiency (11), followed by citrullinemia type I (10), hyperargininemia (5), carbamoyl phosphate synthase 1 deficiency (2) and argininosuccinic aciduria (2). Clinical symptoms were highly severe, being the majority developmental and neurological disabilities, with 20% of death rate. Laboratory analysis revealed high levels of ammonia (mean ± SD: 860 ± 470 μmol/L; reference value: ≤ 80 μmol/L), hypoglycemia, metabolic acidosis, and high excretion of orotic acid in the urine (except in CPS1 deficiency). We emphasize the need of urgent identification of UCD clinical and biochemical conditions, and immediate measurement of ammonia, to enable the correct diagnosis and increase the chances of patients survival, minimizing neurological and psychomotor damage caused by hepatic encephalopathy.
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Affiliation(s)
- Franciele Fátima Lopes
- Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Angela Sitta
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | | | | | - Jéssica Lamberty Faverzani
- Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Bianca Gomes Dos Reis
- Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Moacir Wajner
- Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Carmen Regla Vargas
- Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
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3
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Khaksari K, Chen WL, Gropman AL. Review of Applications of Near-Infrared Spectroscopy in Two Rare Disorders with Executive and Neurological Dysfunction: UCD and PKU. Genes (Basel) 2022; 13:genes13101690. [PMID: 36292574 PMCID: PMC9602148 DOI: 10.3390/genes13101690] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/12/2022] [Accepted: 09/16/2022] [Indexed: 11/16/2022] Open
Abstract
Studying rare diseases, particularly those with neurological dysfunction, is a challenge to researchers and healthcare professionals due to their complexity and small population with geographical dispersion. Universal and standardized biomarkers generated by tools such as functional neuroimaging have been forged to collect baseline data as well as treatment effects. However, the cost and heavily infrastructural requirement of those technologies have substantially limited their availability. Thus, developing non-invasive, portable, and inexpensive modalities has become a major focus for both researchers and clinicians. When considering neurological disorders and diseases with executive dysfunction, EEG is the most convenient tool to obtain biomarkers which can correlate the objective severity and clinical observation of these conditions. However, studies have also shown that EEG biomarkers and clinical observations alone are not sensitive enough since not all the patients present classical phenotypical features or EEG evidence of dysfunction. This article reviews disorders, including two rare disorders with neurological dysfunction and the usefulness of functional near-infrared spectroscopy (fNIRS) as a non-invasive optical modality to obtain hemodynamic biomarkers of diseases and for screening and monitoring the disease.
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Affiliation(s)
- Kosar Khaksari
- Division of Neurogenetics and Developmental Pediatrics, Children’s National Health System, Washington, DC 20010, USA
- Correspondence:
| | - Wei-Liang Chen
- School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Andrea L. Gropman
- Division of Neurogenetics and Developmental Pediatrics, Children’s National Health System, Washington, DC 20010, USA
- Department of Neurology, George Washington University, Washington, DC 20052, USA
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4
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Selvanathan A, Demetriou K, Lynch M, Lipke M, Bursle C, Elliott A, Inwood A, Foyn L, McWhinney B, Coman D, McGill J. N-acetylglutamate synthase deficiency with associated 3-methylglutaconic aciduria: A case report. JIMD Rep 2022; 63:420-424. [PMID: 36101823 PMCID: PMC9458610 DOI: 10.1002/jmd2.12318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 07/01/2022] [Accepted: 07/12/2022] [Indexed: 11/05/2022] Open
Abstract
N-acetylglutamate synthase (NAGS) deficiency is a rare autosomal recessive disorder, which results in the inability to activate the key urea cycle enzyme, carbamoylphosphate synthetase 1 (CPS1). Patients often suffer life-threatening episodes of hyperammonaemia, both in the neonatal period and also at subsequent times of catabolic stress. Because NAGS generates the cofactor for CPS1, these two disorders are difficult to distinguish biochemically. However, there have now been numerous case reports of 3-methylglutaconic aciduria (3-MGA), a marker seen in mitochondrial disorders, occurring in CPS1 deficiency. Previously, this had not been reported in NAGS deficiency. We report a four-day-old neonate who was noted to have 3-MGA at the time of significant hyperammonaemia and lactic acidosis. Low plasma citrulline and borderline orotic aciduria were additional findings that suggested a proximal urea cycle disorder. Subsequent molecular testing identified bi-allelic pathogenic variants in NAGS. The 3-MGA was present at the time of persistent lactic acidosis, but improved with normalization of serum lactate, suggesting that it may reflect secondary mitochondrial dysfunction. NAGS deficiency should therefore also be considered in patients with hyperammonaemia and 3-MGA. Studies in larger numbers of patients are required to determine whether it could be a biomarker for severe decompensations.
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Affiliation(s)
- Arthavan Selvanathan
- Queensland Lifespan Metabolic Medicine ServiceQueensland Children's HospitalBrisbaneAustralia
| | - Kalliope Demetriou
- Queensland Lifespan Metabolic Medicine ServiceQueensland Children's HospitalBrisbaneAustralia
| | - Matthew Lynch
- Queensland Lifespan Metabolic Medicine ServiceQueensland Children's HospitalBrisbaneAustralia
| | - Michelle Lipke
- Queensland Lifespan Metabolic Medicine ServiceQueensland Children's HospitalBrisbaneAustralia
| | - Carolyn Bursle
- Queensland Lifespan Metabolic Medicine ServiceQueensland Children's HospitalBrisbaneAustralia
| | - Aoife Elliott
- Queensland Lifespan Metabolic Medicine ServiceQueensland Children's HospitalBrisbaneAustralia
| | - Anita Inwood
- Queensland Lifespan Metabolic Medicine ServiceQueensland Children's HospitalBrisbaneAustralia
| | - Leanne Foyn
- Chemical Pathology, Central LaboratoryPathology QueenslandHerstonAustralia
| | - Brett McWhinney
- Chemical Pathology, Central LaboratoryPathology QueenslandHerstonAustralia
| | - David Coman
- Queensland Lifespan Metabolic Medicine ServiceQueensland Children's HospitalBrisbaneAustralia
- School of MedicineUniversity of QueenslandBrisbaneAustralia
| | - Jim McGill
- Chemical Pathology, Central LaboratoryPathology QueenslandHerstonAustralia
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5
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Ribas GS, Lopes FF, Deon M, Vargas CR. Hyperammonemia in Inherited Metabolic Diseases. Cell Mol Neurobiol 2021; 42:2593-2610. [PMID: 34665389 DOI: 10.1007/s10571-021-01156-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/10/2021] [Indexed: 12/13/2022]
Abstract
Ammonia is a neurotoxic compound which is detoxified through liver enzymes from urea cycle. Several inherited or acquired conditions can elevate ammonia concentrations in blood, causing severe damage to the central nervous system due to the toxic effects exerted by ammonia on the astrocytes. Therefore, hyperammonemic patients present potentially life-threatening neuropsychiatric symptoms, whose severity is related with the hyperammonemia magnitude and duration, as well as the brain maturation stage. Inherited metabolic diseases caused by enzymatic defects that compromise directly or indirectly the urea cycle activity are the main cause of hyperammonemia in the neonatal period. These diseases are mainly represented by the congenital defects of urea cycle, classical organic acidurias, and the defects of mitochondrial fatty acids oxidation, with hyperammonemia being more severe and frequent in the first two groups mentioned. An effective and rapid treatment of hyperammonemia is crucial to prevent irreversible neurological damage and it depends on the understanding of the pathophysiology of the diseases, as well as of the available therapeutic approaches. In this review, the mechanisms underlying the hyperammonemia and neurological dysfunction in urea cycle disorders, organic acidurias, and fatty acids oxidation defects, as well as the therapeutic strategies for the ammonia control will be discussed.
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Affiliation(s)
- Graziela Schmitt Ribas
- Departamento de Análises Clínicas, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. .,Serviço de Genética Médica, Hospital de Clíınicas de Porto Alegre, Ramiro Barcelos, 2350, Porto Alegre, RS, CEP 90035-003, Brazil.
| | - Franciele Fátima Lopes
- Serviço de Genética Médica, Hospital de Clíınicas de Porto Alegre, Ramiro Barcelos, 2350, Porto Alegre, RS, CEP 90035-003, Brazil
| | - Marion Deon
- Serviço de Genética Médica, Hospital de Clíınicas de Porto Alegre, Ramiro Barcelos, 2350, Porto Alegre, RS, CEP 90035-003, Brazil
| | - Carmen Regla Vargas
- Departamento de Análises Clínicas, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. .,Serviço de Genética Médica, Hospital de Clíınicas de Porto Alegre, Ramiro Barcelos, 2350, Porto Alegre, RS, CEP 90035-003, Brazil.
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6
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Häberle J, Moore MB, Haskins N, Rüfenacht V, Rokicki D, Rubio-Gozalbo E, Tuchman M, Longo N, Yandell M, Andrews A, AhMew N, Caldovic L. Noncoding sequence variants define a novel regulatory element in the first intron of the N-acetylglutamate synthase gene. Hum Mutat 2021; 42:1624-1636. [PMID: 34510628 DOI: 10.1002/humu.24281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/19/2021] [Accepted: 09/08/2021] [Indexed: 11/10/2022]
Abstract
N-acetylglutamate synthase deficiency is an autosomal recessive urea cycle disorder caused either by decreased expression of the NAGS gene or defective NAGS enzyme resulting in decreased production of N-acetylglutamate (NAG), an allosteric activator of carbamylphosphate synthetase 1 (CPS1). NAGSD is the only urea cycle disorder that can be effectively treated with a single drug, N-carbamylglutamate (NCG), a stable NAG analog, which activates CPS1 to restore ureagenesis. We describe three patients with NAGSD due to four novel noncoding sequence variants in the NAGS regulatory regions. All three patients had hyperammonemia that resolved upon treatment with NCG. Sequence variants NM_153006.2:c.427-222G>A and NM_153006.2:c.427-218A>C reside in the 547 bp-long first intron of NAGS and define a novel NAGS regulatory element that binds retinoic X receptor α. Sequence variants NC_000017.10:g.42078967A>T (NM_153006.2:c.-3065A>T) and NC_000017.10:g.42078934C>T (NM_153006.2:c.-3098C>T) reside in the NAGS enhancer, within known HNF1 and predicted glucocorticoid receptor binding sites, respectively. Reporter gene assays in HepG2 and HuH-7 cells demonstrated that all four substitutions could result in reduced expression of NAGS. These findings show that analyzing noncoding regions of NAGS and other urea cycle genes can reveal molecular causes of disease and identify novel regulators of ureagenesis.
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Affiliation(s)
- Johannes Häberle
- Division of Metabolism and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Marvin B Moore
- Department of Human Genetics, University of Utah Health Science Center, Salt Lake City, Utah, USA
| | - Nantaporn Haskins
- Center for Genetic Medicine Research, Children's National Hospital, Washington, District of Columbia, USA
| | - Véronique Rüfenacht
- Division of Metabolism and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Dariusz Rokicki
- Department of Pediatrics, Nutrition and Metabolic Diseases, The Children's Memorial Health Institute, Warsaw, Poland
| | - Estela Rubio-Gozalbo
- Department of Pediatrics and Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Mendel Tuchman
- Center for Genetic Medicine Research, Children's National Hospital, Washington, District of Columbia, USA
| | - Nicola Longo
- Division of Medical Genetics, Department of Pediatrics, University of Utah Health Science Center, Salt Lake City, Utah, USA
| | - Mark Yandell
- Eccles Institute of Human Genetics, University of Utah Health Science Center, Salt Lake City, Utah, USA.,8USTAR Center for Genetic Discovery, University of Utah Health Science Center, Salt Lake City, Utah, USA
| | - Ashley Andrews
- Division of Medical Genetics, Pediatrics, University of Utah Health Science Center, Salt Lake City, Utah, USA
| | - Nicholas AhMew
- Center for Genetic Medicine Research, Children's National Hospital, Washington, District of Columbia, USA
| | - Ljubica Caldovic
- Center for Genetic Medicine Research, Children's National Hospital, Washington, District of Columbia, USA.,Department of Genomics and Precision Medicine, School of Medical and Health Sciences, The George Washington University, Washington, District of Columbia, USA
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7
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Waisbren SE, Stefanatos AK, Kok TMY, Ozturk‐Hismi B. Neuropsychological attributes of urea cycle disorders: A systematic review of the literature. J Inherit Metab Dis 2019; 42:1176-1191. [PMID: 31268178 PMCID: PMC7250134 DOI: 10.1002/jimd.12146] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 06/25/2019] [Accepted: 07/01/2019] [Indexed: 12/30/2022]
Abstract
Urea cycle disorders (UCDs) are rare inherited metabolic conditions that impair the effectiveness of the urea cycle responsible for removing excess ammonia from the body. The estimated incidence of UCDs is 1:35 000 births, or approximately 113 new patients with UCD per year. This review summarizes neuropsychological outcomes among patients with the eight UCDs in reports published since 1980. Rates of intellectual disabilities published before (and including) 2000 and after 2000 were pooled and compared for each UCD. Since diagnoses for UCDs tended to occur earlier and better treatments became more readily available after the turn of the century, this assessment will characterize the extent that current management strategies have improved neuropsychological outcomes. The pooled sample included data on cognitive abilities of 1649 individuals reported in 58 citations. A total of 556 patients (34%) functioned in the range of intellectual disabilities. The decline in the proportion of intellectual disabilities in six disorders, ranged from 7% to 41%. Results from various studies differed and the cohorts varied with respect to age at symptom onset, age at diagnosis and treatment initiation, current age, severity of the metabolic deficiency, management strategies, and ethnic origins. The proportion of cases with intellectual disabilities ranged from 9% to 65% after 2000 in the seven UCDs associated with cognitive deficits. Positive outcomes from some studies suggest that it is possible to prevent or reverse the adverse impact of UCDs on neuropsychological functioning. It is time to "raise the bar" in terms of expectations for treatment effectiveness.
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Affiliation(s)
- Susan E. Waisbren
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's HospitalBostonMassachusetts
- Department of Medicine, Harvard Medical SchoolBostonMassachusetts
| | - Arianna K. Stefanatos
- Department of Child & Adolescent Psychiatry and Behavioral Sciences, Children's Hospital of PhiladelphiaPhiladelphiaPennsylvania
| | | | - Burcu Ozturk‐Hismi
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's HospitalBostonMassachusetts
- Tepecik Education and Research HospitalIzmirTurkey
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8
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Häberle J, Burlina A, Chakrapani A, Dixon M, Karall D, Lindner M, Mandel H, Martinelli D, Pintos-Morell G, Santer R, Skouma A, Servais A, Tal G, Rubio V, Huemer M, Dionisi-Vici C. Suggested guidelines for the diagnosis and management of urea cycle disorders: First revision. J Inherit Metab Dis 2019; 42:1192-1230. [PMID: 30982989 DOI: 10.1002/jimd.12100] [Citation(s) in RCA: 249] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 04/04/2019] [Accepted: 04/08/2019] [Indexed: 02/06/2023]
Abstract
In 2012, we published guidelines summarizing and evaluating late 2011 evidence for diagnosis and therapy of urea cycle disorders (UCDs). With 1:35 000 estimated incidence, UCDs cause hyperammonemia of neonatal (~50%) or late onset that can lead to intellectual disability or death, even while effective therapies do exist. In the 7 years that have elapsed since the first guideline was published, abundant novel information has accumulated, experience on newborn screening for some UCDs has widened, a novel hyperammonemia-causing genetic disorder has been reported, glycerol phenylbutyrate has been introduced as a treatment, and novel promising therapeutic avenues (including gene therapy) have been opened. Several factors including the impact of the first edition of these guidelines (frequently read and quoted) may have increased awareness among health professionals and patient families. However, under-recognition and delayed diagnosis of UCDs still appear widespread. It was therefore necessary to revise the original guidelines to ensure an up-to-date frame of reference for professionals and patients as well as for awareness campaigns. This was accomplished by keeping the original spirit of providing a trans-European consensus based on robust evidence (scored with GRADE methodology), involving professionals on UCDs from nine countries in preparing this consensus. We believe this revised guideline, which has been reviewed by several societies that are involved in the management of UCDs, will have a positive impact on the outcomes of patients by establishing common standards, and spreading and harmonizing good practices. It may also promote the identification of knowledge voids to be filled by future research.
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Affiliation(s)
- Johannes Häberle
- University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland
| | - Alberto Burlina
- Division of Inborn Metabolic Disease, Department of Pediatrics, University Hospital Padua, Padova, Italy
| | - Anupam Chakrapani
- Department of Metabolic Medicine, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Marjorie Dixon
- Dietetics, Great Ormond Street Hospital for Children, NHS Trust, London, UK
| | - Daniela Karall
- Clinic for Pediatrics, Division of Inherited Metabolic Disorders, Medical University of Innsbruck, Innsbruck, Austria
| | - Martin Lindner
- University Children's Hospital, Frankfurt am Main, Germany
| | - Hanna Mandel
- Institute of Human Genetics and metabolic disorders, Western Galilee Medical Center, Nahariya, Israel
| | - Diego Martinelli
- Division of Metabolism, Bambino Gesù Children's Hospital, Rome, Italy
| | - Guillem Pintos-Morell
- Centre for Rare Diseases, University Hospital Vall d'Hebron, Barcelona, Spain
- CIBERER_GCV08, Research Institute IGTP, Barcelona, Spain
- Universitat Autònoma de Barcelona, Barcelona, Spain
| | - René Santer
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anastasia Skouma
- Institute of Child Health, Agia Sofia Children's Hospital, Athens, Greece
| | - Aude Servais
- Service de Néphrologie et maladies métaboliques adulte Hôpital Necker 149, Paris, France
| | - Galit Tal
- The Ruth Rappaport Children's Hospital, Rambam Medical Center, Haifa, Israel
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia (IBV-CSIC), Centro de Investigación Biomédica en Red para Enfermedades Raras (CIBERER), Valencia, Spain
| | - Martina Huemer
- University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland
- Department of Paediatrics, Landeskrankenhaus Bregenz, Bregenz, Austria
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9
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Guo H, Wang J, Yao J, Sun S, Sheng N, Zhang X, Guo X, Guo Y, Sun Y, Dai J. Comparative Hepatotoxicity of Novel PFOA Alternatives (Perfluoropolyether Carboxylic Acids) on Male Mice. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:3929-3937. [PMID: 30865431 DOI: 10.1021/acs.est.9b00148] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
As novel alternatives to perfluorooctanoic acid (PFOA), perfluoropolyether carboxylic acids (multiether PFECAs, CF3(OCF2) nCOO-, n = 2-4) have been detected in various environmental matrices; however, public information regarding their toxicities remains unavailable. To compare the hepatotoxicity of multiether PFECAs (e.g., PFO2HxA, PFO3OA, and PFO4DA) with PFOA, male mice were exposed to 0.4, 2, or 10 mg/kg/d of each chemical for 28 d, respectively. Results demonstrated that PFO2HxA and PFO3OA exposure did not induce marked increases in relative liver weight; whereas 2 and 10 mg/kg/d of PFO4DA significantly increased relative liver weight. Furthermore, PFO2HxA and PFO3OA demonstrated almost no accumulation in the liver or serum; whereas PFO4DA was accumulated but with weaker potential than PFOA. Exposure to 10 mg/kg/d of PFO4DA led to 198 differentially expressed liver genes (56 down-regulated, 142 up-regulated), with bioinformatics analysis highlighting the urea cycle disorder. Like PFOA, 10 mg/kg/d of PFO4DA decreased the urea cycle-related enzyme protein levels (e.g., carbamoyl phosphate synthetase 1) and serum ammonia content in a dose-dependent manner. Both PFOA and PFO4DA treatment (highest concentration) caused a decrease in glutamate content and increase in both glutamine synthetase activity and aquaporin protein levels in the brain. Thus, we concluded that PFO4DA caused hepatotoxicity, as indicated by hepatomegaly and karyolysis, though to a lesser degree than PFOA, and induced urea cycle disorder, which may contribute to the observed toxic effects.
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Affiliation(s)
- Hua Guo
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Jinghua Wang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Jingzhi Yao
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Sujie Sun
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Nan Sheng
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Xiaowen Zhang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology , Chinese Academy of Sciences , Beijing 100101 , China
| | - Xuejiang Guo
- State Key Laboratory of Reproductive Medicine , Nanjing Medical University , Nanjing 210029 , China
| | - Yong Guo
- Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry , Chinese Academy of Sciences , Shanghai 200032 , China
| | - Yan Sun
- Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry , Chinese Academy of Sciences , Shanghai 200032 , China
| | - Jiayin Dai
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology , Chinese Academy of Sciences , Beijing 100101 , China
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10
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N-Acetylglutamate Synthase Deficiency Due to a Recurrent Sequence Variant in the N-acetylglutamate Synthase Enhancer Region. Sci Rep 2018; 8:15436. [PMID: 30337552 PMCID: PMC6194121 DOI: 10.1038/s41598-018-33457-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 09/26/2018] [Indexed: 12/31/2022] Open
Abstract
N-acetylglutamate synthase deficiency (NAGSD, MIM #237310) is an autosomal recessive disorder of the urea cycle that results from absent or decreased production of N-acetylglutamate (NAG) due to either decreased NAGS gene expression or defective NAGS enzyme. NAG is essential for the activity of carbamylphosphate synthetase 1 (CPS1), the first and rate-limiting enzyme of the urea cycle. NAGSD is the only urea cycle disorder that can be treated with a single drug, N-carbamylglutamate (NCG), which can activate CPS1 and completely restore ureagenesis in patients with NAGSD. We describe a novel sequence variant NM_153006.2:c.-3026C > T in the NAGS enhancer that was found in three patients from two families with NAGSD; two patients had hyperammonemia that resolved upon treatment with NCG, while the third patient increased dietary protein intake after initiation of NCG therapy. Two patients were homozygous for the variant while the third patient had the c.-3026C > T variant and a partial uniparental disomy that encompassed the NAGS gene on chromosome 17. The c.-3026C > T sequence variant affects a base pair that is highly conserved in vertebrates; the variant is predicted to be deleterious by several bioinformatics tools. Functional assays in cultured HepG2 cells demonstrated that the c.-3026C > T substitution could result in reduced expression of the NAGS gene. These findings underscore the importance of analyzing NAGS gene regulatory regions when looking for molecular causes of NAGSD.
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Savy N, Brossier D, Brunel-Guitton C, Ducharme-Crevier L, Du Pont-Thibodeau G, Jouvet P. Acute pediatric hyperammonemia: current diagnosis and management strategies. Hepat Med 2018; 10:105-115. [PMID: 30254497 PMCID: PMC6140721 DOI: 10.2147/hmer.s140711] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Acute hyperammonemia may induce a neurologic impairment leading to an acute life-threatening condition. Coma duration, ammonia peak level, and hyperammonemia duration are the main risk factors of hyperammonemia-related neurologic deficits and death. In children, hyperammonemia is mainly caused by severe liver failure and inborn errors of metabolism. In an acute setting, obtaining reliable plasma ammonia levels can be challenging because of the preanalytical difficulties that need to be addressed carefully. The management of hyperammonemia includes 1) identification of precipitating factors and cerebral edema presence, 2) a decrease in ammonia production by reducing protein intake and reversing catabolism, and 3) ammonia removal with pharmacologic treatment and, in the most severe cases, with extracorporeal therapies. In case of severe coma, transcranial Doppler ultrasound could be the method of choice to noninvasively monitor cerebral blood flow and titrate therapies.
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Affiliation(s)
- Nadia Savy
- Department of Pediatrics, CHU Sainte-Justine, University of Montreal, Montreal, QC, Canada,
| | - David Brossier
- Department of Pediatrics, Pediatric Intensive Care Unit, CHU Caen, Caen, France
| | | | | | | | - Philippe Jouvet
- Department of Pediatrics, CHU Sainte-Justine, University of Montreal, Montreal, QC, Canada,
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12
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Shi D, Caldovic L, Tuchman M. Sources and Fates of Carbamyl Phosphate: A Labile Energy-Rich Molecule with Multiple Facets. BIOLOGY 2018; 7:biology7020034. [PMID: 29895729 PMCID: PMC6022934 DOI: 10.3390/biology7020034] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 05/25/2018] [Accepted: 06/07/2018] [Indexed: 11/16/2022]
Abstract
Carbamyl phosphate (CP) is well-known as an essential intermediate of pyrimidine and arginine/urea biosynthesis. Chemically, CP can be easily synthesized from dihydrogen phosphate and cyanate. Enzymatically, CP can be synthesized using three different classes of enzymes: (1) ATP-grasp fold protein based carbamyl phosphate synthetase (CPS); (2) Amino-acid kinase fold carbamate kinase (CK)-like CPS (anabolic CK or aCK); and (3) Catabolic transcarbamylase. The first class of CPS can be further divided into three different types of CPS as CPS I, CPS II, and CPS III depending on the usage of ammonium or glutamine as its nitrogen source, and whether N-acetyl-glutamate is its essential co-factor. CP can donate its carbamyl group to the amino nitrogen of many important molecules including the most well-known ornithine and aspartate in the arginine/urea and pyrimidine biosynthetic pathways. CP can also donate its carbamyl group to the hydroxyl oxygen of a variety of molecules, particularly in many antibiotic biosynthetic pathways. Transfer of the carbamyl group to the nitrogen group is catalyzed by the anabolic transcarbamylase using a direct attack mechanism, while transfer of the carbamyl group to the oxygen group is catalyzed by a different class of enzymes, CmcH/NodU CTase, using a different mechanism involving a three-step reaction, decomposition of CP to carbamate and phosphate, transfer of the carbamyl group from carbamate to ATP to form carbamyladenylate and pyrophosphate, and transfer of the carbamyl group from carbamyladenylate to the oxygen group of the substrate. CP is also involved in transferring its phosphate group to ADP to generate ATP in the fermentation of many microorganisms. The reaction is catalyzed by carbamate kinase, which may be termed as catabolic CK (cCK) in order to distinguish it from CP generating CK. CP is a thermally labile molecule, easily decomposed into phosphate and cyanate, or phosphate and carbamate depending on the pH of the solution, or the presence of enzyme. Biological systems have developed several mechanisms including channeling between enzymes, increased affinity of CP to enzymes, and keeping CP in a specific conformation to protect CP from decomposition. CP is highly important for our health as both a lack of, or decreased, CP production and CP accumulation results in many disease conditions.
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Affiliation(s)
- Dashuang Shi
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA.
- Department of Genomics and Precision Medicine, The George Washington University, Washington, DC 20010, USA.
| | - Ljubica Caldovic
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA.
- Department of Genomics and Precision Medicine, The George Washington University, Washington, DC 20010, USA.
| | - Mendel Tuchman
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA.
- Department of Genomics and Precision Medicine, The George Washington University, Washington, DC 20010, USA.
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13
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Cavicchi C, Chilleri C, Fioravanti A, Ferri L, Ripandelli F, Costa C, Calabresi P, Prontera P, Pochiero F, Pasquini E, Funghini S, la Marca G, Donati MA, Morrone A. Late-Onset N-Acetylglutamate Synthase Deficiency: Report of a Paradigmatic Adult Case Presenting with Headaches and Review of the Literature. Int J Mol Sci 2018; 19:ijms19020345. [PMID: 29364180 PMCID: PMC5855567 DOI: 10.3390/ijms19020345] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 01/17/2018] [Accepted: 01/18/2018] [Indexed: 12/30/2022] Open
Abstract
N-acetylglutamate synthase deficiency (NAGSD) is an extremely rare urea cycle disorder (UCD) with few adult cases so far described. Diagnosis of late-onset presentations is difficult and delayed treatment may increase the risk of severe hyperammonemia. We describe a 52-year-old woman with recurrent headaches who experienced an acute onset of NAGSD. As very few papers focus on headaches in UCDs, we also report a literature review of types and pathophysiologic mechanisms of UCD-related headaches. In our case, headaches had been present since puberty (3–4 days a week) and were often accompanied by nausea, vomiting, or behavioural changes. Despite three previous episodes of altered consciousness, ammonia was measured for the first time at 52 years and levels were increased. Identification of the new homozygous c.344C>T (p.Ala115Val) NAGS variant allowed the definite diagnosis of NAGSD. Bioinformatic analysis suggested that an order/disorder alteration of the mutated form could affect the arginine-binding site, resulting in poor enzyme activation and late-onset presentation. After optimized treatment for NAGSD, ammonia and amino acid levels were constantly normal and prevented other headache bouts. The manuscript underlies that headache may be the presenting symptom of UCDs and provides clues for the rapid diagnosis and treatment of late-onset NAGSD.
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Affiliation(s)
- Catia Cavicchi
- Molecular and Cell Biology Laboratory of Neurometabolic Diseases, Neuroscience Department, Meyer Children's Hospital, 50139 Florence, Italy.
| | - Chiara Chilleri
- Molecular and Cell Biology Laboratory of Neurometabolic Diseases, Neuroscience Department, Meyer Children's Hospital, 50139 Florence, Italy.
| | - Antonella Fioravanti
- Structural Biology Researcher Center, VIB, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
| | - Lorenzo Ferri
- Molecular and Cell Biology Laboratory of Neurometabolic Diseases, Neuroscience Department, Meyer Children's Hospital, 50139 Florence, Italy.
| | | | - Cinzia Costa
- Neurology Unit, Santa Maria della Misericordia Hospital, 06123 Perugia, Italy.
| | - Paolo Calabresi
- Neurology Unit, Santa Maria della Misericordia Hospital, 06123 Perugia, Italy.
| | - Paolo Prontera
- Medical Genetics Unit, Santa Maria della Misericordia Hospital, 06123 Perugia, Italy.
| | - Francesca Pochiero
- Metabolic and Muscular Unit, Neuroscience Department, Meyer Children's Hospital, 50139 Florence, Italy.
| | - Elisabetta Pasquini
- Metabolic and Muscular Unit, Neuroscience Department, Meyer Children's Hospital, 50139 Florence, Italy.
| | - Silvia Funghini
- Newborn Screening, Biochemistry and Pharmacology Laboratory, Neuroscience Department, Meyer Children's Hospital, 50139 Florence, Italy.
| | - Giancarlo la Marca
- Newborn Screening, Biochemistry and Pharmacology Laboratory, Neuroscience Department, Meyer Children's Hospital, 50139 Florence, Italy.
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50139 Florence, Italy.
| | - Maria Alice Donati
- Metabolic and Muscular Unit, Neuroscience Department, Meyer Children's Hospital, 50139 Florence, Italy.
| | - Amelia Morrone
- Molecular and Cell Biology Laboratory of Neurometabolic Diseases, Neuroscience Department, Meyer Children's Hospital, 50139 Florence, Italy.
- Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, 50139 Florence, Italy.
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14
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Bigot A, Tchan MC, Thoreau B, Blasco H, Maillot F. Liver involvement in urea cycle disorders: a review of the literature. J Inherit Metab Dis 2017; 40:757-769. [PMID: 28900784 DOI: 10.1007/s10545-017-0088-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 08/13/2017] [Accepted: 08/29/2017] [Indexed: 12/20/2022]
Abstract
Urea cycle disorders (UCDs) are inborn errors of metabolism of the nitrogen detoxification pathway and encompass six principal enzymatic deficiencies. The aging of UCD patients leads to a better knowledge of the long-term natural history of the condition and to the reporting of previously unnoticed manifestations. Despite historical evidence of liver involvement in UCDs, little attention has been paid to this organ until recently. Hence, we reviewed the available scientific evidence on acute and chronic liver dysfunction and liver carcinogenesis in UCDs and discuss their pathophysiology. Overall, liver involvement, such as acute liver failure or steatotic-like disease, which may evolve toward cirrhosis, has been reported in all six main UCDs. Excessive glycogen storage is also a prominent histologic feature, and hypoglycemia has been reported in citrin deficiency. Hepatocarcinomas seem frequent in some UCDs, such as in citrin deficiency, and can sometimes occur in non-cirrhotic patients. UCDs may differ in liver involvement according to the enzymatic deficiency. Ornithine transcarbamylase deficiency may be associated more with acute liver failure and argininosuccinic aciduria with chronic liver failure and cirrhosis. Direct toxicity of metabolites, downstream metabolic deficiencies, impaired tricarboxylic acid cycle, oxidative stress, mitochondrial dysfunction, energy deficit, and putative toxicity of therapies combine in various ways to cause the different liver diseases reported.
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Affiliation(s)
- Adrien Bigot
- CHRU de Tours, service médecine interne, Tours, France.
- CHRU de Tours, centre de référence des maladies héréditaires du métabolisme, Tours, France.
- Department of Genetic Medicine, Westmead Hospital, Sydney, Australia.
- Service de Médecine Interne, Hôpital Bretonneau, 2, boulevard Tonnelle, 37044, Tours, France.
| | - Michel C Tchan
- Department of Genetic Medicine, Westmead Hospital, Sydney, Australia
| | - Benjamin Thoreau
- CHRU de Tours, service médecine interne, Tours, France
- CHRU de Tours, centre de référence des maladies héréditaires du métabolisme, Tours, France
- Université François Rabelais, Tours, France
- UMR INSERM U 1069, Tours, France
| | - Hélène Blasco
- CHRU de Tours, centre de référence des maladies héréditaires du métabolisme, Tours, France
- Université François Rabelais, Tours, France
- CHRU de Tours, service de biochimie-biologie moléculaire, Tours, France
- UMR INSERM U930, 37000, Tours, France
| | - François Maillot
- CHRU de Tours, service médecine interne, Tours, France
- CHRU de Tours, centre de référence des maladies héréditaires du métabolisme, Tours, France
- Université François Rabelais, Tours, France
- UMR INSERM U 1069, Tours, France
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15
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Chapel-Crespo CC, Diaz GA, Oishi K. Efficacy of N-carbamoyl-L-glutamic acid for the treatment of inherited metabolic disorders. Expert Rev Endocrinol Metab 2016; 11:467-473. [PMID: 30034506 PMCID: PMC6054484 DOI: 10.1080/17446651.2016.1239526] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
INTRODUCTION N-carbamoyl-L-glutamic acid (NCG) is a synthetic analogue of N-acetyl glutamate (NAG) that works effectively as a cofactor for carbamoyl phosphate synthase 1 and enhances ureagenesis by activating the urea cycle. NCG (brand name, Carbaglu) was recently approved by the United States Food and Drug Administration (US FDA) for the management of NAGS deficiency and by the European Medicines Agency (EMA) for the treatment of NAGS deficiency as well as for the treatment of hyperammonenia in propionic, methylmalonic and isovaleric acidemias in Europe. AREAS COVERED The history, mechanism of action, and efficacy of this new drug are described. Moreover, clinical utility of NCG in a variety of inborn errors of metabolism with secondary NAGS deficiency is discussed. EXPERT COMMENTARY NCG has favorable pharmacological features including better bioavailability compared to NAG. The clinical use of NCG has proven to be so effective as to make dietary protein restriction unnecessary for patients with NAGS deficiency. It has been also demonstrated to be effective for hyperammonemia secondary to other types of inborn errors of metabolism. NCG may have additional therapeutic potential in conditions such as hepatic hyperammonemic encephalopathy secondary to chemotherapies or other liver pathology.
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Affiliation(s)
- Cristel C Chapel-Crespo
- Department of Genetics and Genomic Sciences, Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - George A Diaz
- Department of Genetics and Genomic Sciences, Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Kimihiko Oishi
- Department of Genetics and Genomic Sciences, Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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16
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Al Kaabi EH, El-Hattab AW. N-acetylglutamate synthase deficiency: Novel mutation associated with neonatal presentation and literature review of molecular and phenotypic spectra. Mol Genet Metab Rep 2016; 8:94-8. [PMID: 27570737 PMCID: PMC4992009 DOI: 10.1016/j.ymgmr.2016.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 08/07/2016] [Accepted: 08/07/2016] [Indexed: 12/30/2022] Open
Abstract
The urea cycle is the main pathway for the disposal of excess nitrogen. Carbamoylphosphate synthetase 1 (CPS1), the first and rate-limiting enzyme of urea cycle, is activated by N-acetylglutamate (NAG), and thus N-acetylglutamate synthase (NAGS) is an essential part of the urea cycle. Although NAGS deficiency is the rarest urea cycle disorder, it is the only one that can be specifically and effectively treated by a drug, N-carbamylglutamate, a stable structural analogous of NAG that activates CPS1. Here we report an infant with NAGS deficiency who presented with neonatal hyperammonemia. She was found to have a novel homozygous splice-site mutation, c.1097-2A>T, in the NAGS gene. We describe the clinical course of this infant, who had rapid response to N-carbamylglutamate treatment. In addition, we reviewed the clinical and molecular spectra of previously reported individuals with NAGS deficiency, which presents in most cases with neonatal hyperammonemia, and in some cases the presentation is later, with a broad spectrum of ages and manifestations. With this broad later-onset phenotypic spectrum, maintaining a high index of suspicion is needed for the early diagnosis of this treatable disease.
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Affiliation(s)
- Eiman H Al Kaabi
- Pediatrics Department, Tawam Hospital, Al-Ain, United Arab Emirates
| | - Ayman W El-Hattab
- Division of Clinical Genetics and Metabolic Disorders, Pediatrics Department, Tawam Hospital, Al-Ain, United Arab Emirates
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17
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Hyperammonemia due to Adult-Onset N-Acetylglutamate Synthase Deficiency. JIMD Rep 2016; 31:95-99. [PMID: 27147233 DOI: 10.1007/8904_2016_565] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 03/25/2016] [Accepted: 03/29/2016] [Indexed: 03/29/2023] Open
Abstract
A 59-year-old woman, with a medical history of intellectual disability after perinatal asphyxia, was admitted because of coma due to hyperammonemia after she was treated for a fracture of the pelvis. The ammonia level was 280 μM. Acquired disorders as explanation for the hyperammonemia were excluded. Metabolic investigations showed an elevated glutamine and alanine and low citrulline, suspect for a urea cycle defect (UCD). Orotic acid could not be demonstrated in urine. DNA investigations were negative for mutations or deletions in the OTC and CPS1 gene, but revealed a homozygous c.603G>C mutation in exon 2 of the N-acetylglutamate synthase (NAGS) gene (NM_153006.2:c.603G>C), which mandates p.Lys201Asn. This is a novel mutation in the NAGS gene.After the diagnosis of NAGS deficiency was made carbamylglutamate was started in a low dose. In combination with mild protein restriction the ammonia level decreased to 26 μM.This is one of the first patients in literature in whom the diagnosis of a UCD is made at such an advanced age. It is important for the adult physician to consider a metabolic disorder at every age.
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18
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Chaturvedi S, Singh AK, Keshari AK, Maity S, Sarkar S, Saha S. Human Metabolic Enzymes Deficiency: A Genetic Mutation Based Approach. SCIENTIFICA 2016; 2016:9828672. [PMID: 27051561 PMCID: PMC4804091 DOI: 10.1155/2016/9828672] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/21/2016] [Accepted: 01/31/2016] [Indexed: 05/30/2023]
Abstract
One of the extreme challenges in biology is to ameliorate the understanding of the mechanisms which emphasize metabolic enzyme deficiency (MED) and how these pretend to have influence on human health. However, it has been manifested that MED could be either inherited as inborn error of metabolism (IEM) or acquired, which carries a high risk of interrupted biochemical reactions. Enzyme deficiency results in accumulation of toxic compounds that may disrupt normal organ functions and cause failure in producing crucial biological compounds and other intermediates. The MED related disorders cover widespread clinical presentations and can involve almost any organ system. To sum up the causal factors of almost all the MED-associated disorders, we decided to embark on a less traveled but nonetheless relevant direction, by focusing our attention on associated gene family products, regulation of their expression, genetic mutation, and mutation types. In addition, the review also outlines the clinical presentations as well as diagnostic and therapeutic approaches.
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Affiliation(s)
- Swati Chaturvedi
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Raebareli Road, Vidyavihar, Lucknow 226025, India
| | - Ashok K. Singh
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Raebareli Road, Vidyavihar, Lucknow 226025, India
| | - Amit K. Keshari
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Raebareli Road, Vidyavihar, Lucknow 226025, India
| | - Siddhartha Maity
- Department of Pharmaceutical Technology, Jadavpur University, Kolkata 700032, India
| | - Srimanta Sarkar
- Dr. Reddy's Laboratories Limited, Bachupally, Hyderabad, Telangana 502325, India
| | - Sudipta Saha
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Raebareli Road, Vidyavihar, Lucknow 226025, India
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19
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Chen CT, Chen YC, Yamaguchi H, Hung MC. Carglumic acid promotes apoptosis and suppresses cancer cell proliferation in vitro and in vivo. Am J Cancer Res 2015; 5:3560-3569. [PMID: 26885446 PMCID: PMC4731631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 06/19/2015] [Indexed: 06/05/2023] Open
Abstract
Drug repurposing is a therapeutic strategy that applies drugs to treat different diseases based on new therapeutic function. Carglumic acid (Carbaglu; Orphan Europe) is an orphan drug approved by the FDA for hyperammonemia. Administration of carglumic acid for treatment of hyperammonemia has few side effects and has been used for 10 years to effectively treat hyperammonemia symptoms of both adult and pediatric patients. Here, we tested the potential of carglumic acid to be repurposed as an anticancer agent and showed that carglumic acid promotes apoptosis and inhibits cancer cell growth ina wide variety of human cancers, including pancreatic ductal adenocarcinoma, triple-negative breast cancer (TNBC), hepatoma, and lung cancer. Our data from in vivo models indicates that orally taking 10% of the carglumic acid dose currently used for the treatment of hyperammonemia ise ffective to suppress the growth of pancreatic ductal adenocarcinomaand TNBC. If given intravenously, only 5% of the carglumic acid doseis needed to be effective against TNBC. These findings suggest that carglumic acid may serve as a safe and effective therapeutic to treat both TNBC and pancreatic cancer.
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Affiliation(s)
- Chun-Te Chen
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer CenterHouston, Texas 77030, USA
| | - Yi-Chun Chen
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer CenterHouston, Texas 77030, USA
| | - Hirohito Yamaguchi
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer CenterHouston, Texas 77030, USA
| | - Mien-Chie Hung
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer CenterHouston, Texas 77030, USA
- Center for Molecular Medicine and Graduate Institute of Cancer Biology, China Medical UniversityTaichung 404, Taiwan
- Department of Biotechnology, Asia UniversityTaichung 413, Taiwan
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21
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Feldman B, Tuchman M, Caldovic L. A zebrafish model of hyperammonemia. Mol Genet Metab 2014; 113:142-7. [PMID: 25069822 PMCID: PMC4191821 DOI: 10.1016/j.ymgme.2014.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 07/01/2014] [Accepted: 07/01/2014] [Indexed: 02/08/2023]
Abstract
Hyperammonemia is the principal consequence of urea cycle defects and liver failure, and the exposure of the brain to elevated ammonia concentrations leads to a wide range of neuro-cognitive deficits, intellectual disabilities, coma and death. Current treatments focus almost exclusively on either reducing ammonia levels through the activation of alternative pathways for ammonia disposal or on liver transplantation. Ammonia is toxic to most fish and its pathophysiology appears to be similar to that in mammals. Since hyperammonemia can be induced in fish simply by immersing them in water with elevated concentration of ammonia, we sought to develop a zebrafish (Danio rerio) model of hyperammonemia. When exposed to 3mM ammonium acetate (NH4Ac), 50% of 4-day old (dpf) fish died within 3hours and 4mM NH4Ac was 100% lethal. We used 4dpf zebrafish exposed to 4mM NH4Ac to test whether the glutamine synthetase inhibitor methionine sulfoximine (MSO) and/or NMDA receptor antagonists MK-801, memantine and ketamine, which are known to protect the mammalian brain from hyperammonemia, prolong survival of hyperammonemic fish. MSO, MK-801, memantine and ketamine all prolonged the lives of the ammonia-treated fish. Treatment with the combination of MSO and an NMDA receptor antagonist was more effective than either drug alone. These results suggest that zebrafish can be used to screen for ammonia-neuroprotective agents. If successful, drugs that are discovered in this screen could complement current treatment approaches to improve the outcome of patients with hyperammonemia.
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Affiliation(s)
- B Feldman
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - M Tuchman
- Children's National Medical Center, Washington DC, USA
| | - L Caldovic
- Children's National Medical Center, Washington DC, USA.
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22
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Ah Mew N, McCarter R, Daikhin Y, Lichter U, Nissim I, Yudkoff M, Tuchman AM. Augmenting ureagenesis in patients with partial carbamyl phosphate synthetase 1 deficiency with N-carbamyl-L-glutamate. J Pediatr 2014; 165:401-403.e3. [PMID: 24880889 PMCID: PMC4111993 DOI: 10.1016/j.jpeds.2014.04.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 03/05/2014] [Accepted: 04/07/2014] [Indexed: 11/30/2022]
Abstract
Identical studies using stable isotopes were performed before and after a 3-day trial of oral N-carbamyl-l-glutamate (NCG) in 5 subjects with late-onset carbamyl phosphate synthetase deficiency. NCG augmented ureagenesis and decreased plasma ammonia in 4 of 5 subjects. There was marked improvement in nitrogen metabolism with long-term NCG administration in 1 subject.
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Affiliation(s)
- Nicholas Ah Mew
- Center for Translational Sciences, Children's National Health System, The George Washington University, Washington, DC 20010, USA, Division of Genetics and Metabolism, Children's National Health System, The George Washington University, Washington, DC 20010, USA,Corresponding author: Nicholas Ah Mew Division of Genetics and Metabolism Children's National Health System 111 Michigan Avenue, NW Washington, DC 20010, USA Telephone: (202) 476-5863 Fax: (202) 476-5650
| | - Robert McCarter
- Center for Translational Sciences, Children's National Health System, The George Washington University, Washington, DC 20010, USA
| | - Yevgeny Daikhin
- Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Uta Lichter
- Center for Translational Sciences, Children's National Health System, The George Washington University, Washington, DC 20010, USA, Division of Genetics and Metabolism, Children's National Health System, The George Washington University, Washington, DC 20010, USA
| | - Ilana Nissim
- Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Marc Yudkoff
- Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - and Mendel Tuchman
- Center for Genetic Medicine Research, Children's National Health System, The George Washington University, Washington, DC 20010, USA
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Abstract
N-acetyl-glutamate synthase (NAGS) deficiency is a rare autosomal recessive urea cycle disorder (UCD) that uncommonly presents in adulthood. Adult presentations of UCDs include; confusional episodes, neuropsychiatric symptoms and encephalopathy. To date, there have been no detailed neurological descriptions of an adult onset presentation of NAGS deficiency. In this review we examine the clinical presentation and management of UCDs with an emphasis on NAGS deficiency. An illustrative case is provided. Plasma ammonia levels should be measured in all adult patients with unexplained encephalopathy, as treatment can be potentially life-saving. Availability of N-carbamylglutamate (NCG; carglumic acid) has made protein restriction largely unnecessary in treatment regimens currently employed. Genetic counselling remains an essential component of management of NAGS.
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Senkevitch E, Cabrera-Luque J, Morizono H, Caldovic L, Tuchman M. A novel biochemically salvageable animal model of hyperammonemia devoid of N-acetylglutamate synthase. Mol Genet Metab 2012; 106:160-8. [PMID: 22503289 PMCID: PMC3356441 DOI: 10.1016/j.ymgme.2012.03.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 03/09/2012] [Accepted: 03/09/2012] [Indexed: 02/05/2023]
Abstract
All knockout mouse models of urea cycle disorders die in the neonatal period or shortly thereafter. Since N-acetylglutamate synthase (NAGS) deficiency in humans can be effectively treated with N-carbamyl-l-glutamate (NCG), we sought to develop a mouse model of this disorder that could be rescued by biochemical intervention, reared to adulthood, reproduce, and become a novel animal model for hyperammonemia. Founder NAGS knockout heterozygous mice were obtained from the trans-NIH Knock-Out Mouse Project. Genotyping of the mice was performed by PCR and confirmed by Western blotting of liver and intestine. NCG and L-citrulline (Cit) were used to rescue the NAGS knockout homozygous (Nags(-/-)) pups and the rescued animals were characterized. We observed an 85% survival rate of Nags(-/-) mice when they were given intraperitoneal injections with NCG and Cit during the newborn period until weaning and supplemented subsequently with both compounds in their drinking water. This regimen has allowed for normal development, apparent health, and reproduction. Interruption of this rescue intervention resulted in the development of severe hyperammonemia and death within 48 h. In addition to hyperammonemia, interruption of rescue supplementation was associated with elevated plasma glutamine, glutamate, and lysine, and reduced citrulline, arginine, ornithine and proline levels. We conclude that NAGS deprived mouse model has been developed which can be rescued by NCG and Cit and reared to reproduction and beyond. This biochemically salvageable mouse model recapitulates the clinical phenotype of proximal urea cycle disorders and can be used as a reliable model of induced hyperammonemia by manipulating the administration of the rescue compounds.
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Affiliation(s)
- Emilee Senkevitch
- Research Center for Genetic Medicine, Children’s National Medical Center, Washington DC, USA
- Biological Sciences Program, University of Maryland, College Park, Maryland, USA
| | - Juan Cabrera-Luque
- Research Center for Genetic Medicine, Children’s National Medical Center, Washington DC, USA
| | - Hiroki Morizono
- Research Center for Genetic Medicine, Children’s National Medical Center, Washington DC, USA
| | - Ljubica Caldovic
- Research Center for Genetic Medicine, Children’s National Medical Center, Washington DC, USA
| | - Mendel Tuchman
- Research Center for Genetic Medicine, Children’s National Medical Center, Washington DC, USA
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25
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Häberle J. Carglumic acid for the treatment of N-acetylglutamate synthase deficiency and acute hyperammonemia. Expert Rev Endocrinol Metab 2012; 7:263-271. [PMID: 30780843 DOI: 10.1586/eem.12.17] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Carglumic acid is a structural analog and the first registered synthetic form of the naturally occurring allosteric activator of the urea cycle, N-acetylglutamate (NAG), which is the product of the enzyme NAG synthase (NAGS). Because NAG is essential for the function of carbamoylphosphate synthetase 1 as the first step of the urea cycle, a decreased availability of NAG due to primary or secondary defects of NAGS will affect ammonia detoxification in the urea cycle. Carglumic acid (Carbaglu®, Orphan Europe SARL, Paris, France) is approved for the acute and long-term treatment of primary defects of NAGS in Europe and the USA. In addition, it is approved in Europe for the treatment of acute hyperammonemia in patients with specific organic acidurias that can lead to NAG deficiency secondary to inhibition of NAGS. This article reviews the use of carglumic acid for both approved indications and considers the potential of this compound for acute hyperammonemias in general.
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Affiliation(s)
- Johannes Häberle
- a University Children's Hospital, Division of Metabolism, Children's Research Center, Steinwiesstrasse 75, CH-8032 Zürich, Switzerland.
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