Home / Deep Research / N-Acetylglutamate Synthase Deficiency

N-Acetylglutamate Synthase Deficiency

Disease Pathophysiology Research Template

2026-02-23
Falcon MONDO:0009377 Model: Edison Scientific Literature 49 citations

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Pathophysiology Research Template

Target Disease

  • Disease Name: N-acetylglutamate Synthase Deficiency
  • MONDO ID: (if available)
  • Category: Genetic

Research Objectives

Please provide a comprehensive research report on the pathophysiology of N-acetylglutamate Synthase Deficiency. Focus on the molecular and cellular mechanisms underlying disease progression.

Required Information

1. Core Pathophysiology

  • What are the primary pathophysiological mechanisms?
  • What molecular pathways are dysregulated?
  • What cellular processes are affected?

2. Key Molecular Players

  • Genes/Proteins: Which genes are causally involved or implicated?
  • Chemical Entities: What metabolites, drugs, or small molecules are relevant?
  • Cell Types: Which cell types are primarily affected?
  • Anatomical Locations: Which tissues/organs are involved?

3. Biological Processes (for GO annotation)

  • What biological processes (GO terms) are disrupted?
  • Consider: signaling pathways, metabolic processes, cellular responses, transport, etc.

4. Cellular Components

  • Where in the cell do key processes occur?
  • Consider: organelles, membrane compartments, extracellular space, etc.

5. Disease Progression

  • What is the sequence of events from initial trigger to clinical manifestation?
  • Are there distinct stages or phases?

6. Phenotypic Manifestations

  • What are the key clinical phenotypes?
  • How do they relate to the underlying mechanisms?

Citation Requirements

  • Cite primary literature (PMID preferred) for all mechanistic claims
  • Prioritize recent reviews and landmark papers
  • Include direct quotes where possible to support key statements

Output Format

Structure your response as a narrative that could be used to populate a disease knowledge base entry with: - Pathophysiology description - Gene/protein annotations with ontology terms (HGNC, GO) - Phenotype associations (HP terms) - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Evidence items with PMIDs

Disease pathophysiology research report: N-acetylglutamate synthase (NAGS) deficiency (hyperammonemia due to N-acetylglutamate synthase deficiency)

1) Disease definition, identifiers, and current understanding N-acetylglutamate synthase deficiency (NAGSD; also written NAGS deficiency) is an inherited proximal urea-cycle disorder in which loss of hepatic mitochondrial N-acetylglutamate synthase (NAGS) activity reduces production of N-acetyl-L-glutamate (NAG), the obligate allosteric activator (“cofactor”) required for carbamoyl phosphate synthetase 1 (CPS1) function, thereby impairing ureagenesis and causing hyperammonemia. Clinically, NAGSD is “phenotypically identical” to CPS1 deficiency and lacks “reliable differential biomarkers,” making molecular diagnosis essential for targeted treatment decisions. (gougeard2024useofpure pages 1-2, singh2024theefficacyof pages 1-2)

Disease identifiers • MONDO: MONDO_0009377 (“hyperammonemia due to N-acetylglutamate synthase deficiency”). (erdal2025aminoacidmetabolism pages 10-12) • Orphanet: 927 (“Hyperammonemia due to N-acetylglutamate synthetase deficiency”). (erdal2025aminoacidmetabolism pages 10-12) • OMIM/MIM: 237310 (N-acetylglutamate synthase deficiency). (gougeard2024useofpure pages 1-2)

Epidemiology NAGSD is extremely rare. A 2024 case series states an incidence of “less than one in 2,000,000 live births.” (singh2024theefficacyof pages 1-2) Older estimates (based on relative frequency among UCDs) place it at ~1:3,500,000–7,000,000, and 0.5–1% of urea cycle disorders. (kaabi2016nacetylglutamatesynthasedeficiency pages 1-2)

Inheritance and causal gene NAGSD is autosomal recessive and caused by pathogenic variation in NAGS. (singh2024theefficacyof pages 1-2, kenneson2020presentationandmanagement pages 1-3)

2) Core pathophysiology (molecular → cellular → organ-level) 2.1 Primary biochemical lesion: failure to generate CPS1’s activator (NAG) NAGS catalyzes NAG formation from acetyl-CoA and L-glutamate. In mammals, its major role is to “produce the essential cofactor for carbamoyl phosphate synthetase 1 (CPS1) in the urea cycle.” (shi2015thenacetylglutamatesynthase pages 1-3) NAG is the physiological CPS1 activator: “Cohen's group identified NAG as the natural activator” of CPS1 (carbamoyl phosphate synthesis). (fernandez2015usingrecombinanthuman pages 37-41) Functionally, CPS1 is off without NAG; CPS1 is described as a metabolic switch: “human CPS1 is inactive without NAG,” turning the urea cycle on/off depending on NAG availability. (fernandez2015usingrecombinanthuman pages 34-37) Thus, NAGS loss → low NAG → underactivated CPS1 → reduced carbamoyl phosphate formation → reduced urea cycle flux → hyperammonemia. (singh2024theefficacyof pages 1-2, erdal2025aminoacidmetabolism pages 10-12)

2.2 Subcellular and tissue context NAGS localization: “Mammalian NAGS is found in the mitochondrial matrix of cells of the liver and intestines.” (shi2015thenacetylglutamatesynthase pages 3-6) Urea-cycle zonation: ammonia detoxification through CPS1 occurs in periportal hepatocytes, whereas glutamine synthetase is restricted to perivenous hepatocytes, highlighting the liver’s spatial partitioning of nitrogen handling. (fernandez2015usingrecombinanthuman pages 37-41)

2.3 Dysregulated pathways and cellular processes Core dysregulated pathway: urea cycle / ammonia detoxification. NAGS deficiency “results in dysregulation of ammonia detoxification.” (singh2024theefficacyof pages 1-2) A key regulatory axis is arginine → NAGS → NAG → CPS1. Mammalian NAGS is strongly regulated by L-arginine; in vitro, “Enzymatic activity ... more than doubles (2–5-fold) in the presence of L-arginine.” (shi2015thenacetylglutamatesynthase pages 3-6)

2.4 Secondary systemic and neurological pathophysiology of hyperammonemia Ammonia is the unifying toxic driver: “The common biochemical trait of all UCDs is hyperammonaemia,” and ammonia “can freely diffuse across the blood–brain barrier.” (haberle2020primaryhyperammonaemiacurrent pages 3-4) Brain edema mechanism: brain edema occurs “due to the accumulation of glutamine,” and glutamine “acts as an osmolyte leading to astrocytic water retention.” (haberle2020primaryhyperammonaemiacurrent pages 3-4) Neurotransmission and mitochondrial effects: hyperammonemia-associated glutamine accumulation is linked to “changes of glutamate and N-methyl-d-aspartate (NMDA)-mediated neurotransmission and brain mitochondrial function.” (haberle2020primaryhyperammonaemiacurrent pages 3-4) A complementary ICU-focused synthesis describes the astrocyte mechanism: ammonia is converted to glutamine by glutamine synthase; as glutamine is “the main intracellular osmole of the brain,” its accumulation causes “swelling of astrocytes,” potentially progressing to intracranial hypertension, coma, and death if untreated. (redant2021managementoflate pages 1-3)

3) Key molecular players 3.1 Genes/proteins Causal gene/protein • NAGS (HGNC: NAGS; protein: N-acetylglutamate synthase). (singh2024theefficacyof pages 1-2, gougeard2024useofpure pages 1-2) Key interacting/functional partner • CPS1 (carbamoyl phosphate synthetase 1), the “first and controlling enzyme” of the urea cycle activated by NAG. (gougeard2024useofpure pages 2-4)

Variant-to-function mechanisms (2024 mechanistic advance) A major 2024 experimental study used stabilized recombinant human NAGS to functionally characterize 23 patient nonsynonymous variants, showing that pathogenicity is typically explained by specific biochemical defects including “loss of arginine activation, increased KmGlutamate, active site inactivation, decreased thermal stability, and protein misfolding.” (gougeard2024useofpure pages 1-2) The same study emphasizes loss of arginine activation as a dominant mechanism: “hampered NAGS activation by arginine has emerged as a paramount causative factor of NAGSD.” (gougeard2024useofpure pages 12-14)

3.2 Chemical entities and metabolites (with biomedical relevance) • N-acetyl-L-glutamate (NAG): essential CPS1 activator/cofactor. (shi2015thenacetylglutamatesynthase pages 1-3, fernandez2015usingrecombinanthuman pages 37-41) • Ammonia (NH3/NH4+): toxic metabolite accumulating systemically. (haberle2020primaryhyperammonaemiacurrent pages 3-4) • Glutamine: rises in blood and brain; contributes to cerebral edema via osmotic astrocyte swelling. (haberle2020primaryhyperammonaemiacurrent pages 3-4, redant2021managementoflate pages 1-3) • Citrulline: commonly decreased in proximal UCDs including NAGSD (but can be variable in newer case series). (kenneson2020presentationandmanagement pages 1-3, singh2024theefficacyof pages 2-4) • Orotic acid (urine): typically normal in NAGSD (distinguishing from distal blocks), but mild elevations have been reported in some NAGSD cases. (kenneson2020presentationandmanagement pages 1-3, singh2024theefficacyof pages 2-4) • Substrates: acetyl-CoA and glutamate (NAGS reaction substrates). (shi2015thenacetylglutamatesynthase pages 1-3, haskins2016effectofarginine pages 1-2)

Therapeutic small molecule • N-carbamyl-L-glutamate / carbamylglutamate / carglumic acid (drug; Carbaglu®): bioavailable NAG analog that activates CPS1 and bypasses deficient NAGS. (singh2024theefficacyof pages 1-2, gougeard2024useofpure pages 1-2)

3.3 Cell types and anatomical locations Cell types (CL-aligned) • Hepatocytes, especially periportal hepatocytes (primary site of urea cycle and CPS1 activity). (fernandez2015usingrecombinanthuman pages 37-41, savy2018acutepediatrichyperammonemia pages 1-2) • Astrocytes (brain ammonia detoxification via glutamine synthetase; cell swelling drives edema). (haberle2020primaryhyperammonaemiacurrent pages 3-4, redant2021managementoflate pages 1-3)

Anatomical locations (UBERON-aligned) • Liver (mitochondrial urea cycle compartment; periportal zone). (fernandez2015usingrecombinanthuman pages 37-41) • Intestine (NAGS expression in mitochondrial matrix of intestinal cells). (shi2015thenacetylglutamatesynthase pages 3-6) • Brain (site of ammonia neurotoxicity; cerebral edema/encephalopathy). (haberle2020primaryhyperammonaemiacurrent pages 3-4)

4) Biological processes disrupted (GO-oriented) The following GO-relevant processes are disrupted or centrally involved: • Urea cycle / ureagenesis / ammonia detoxification (loss of CPS1 activation due to low NAG). (shi2015thenacetylglutamatesynthase pages 1-3, singh2024theefficacyof pages 1-2) • N-acetylglutamate biosynthetic process (loss of NAGS activity). (shi2015thenacetylglutamatesynthase pages 1-3) • Regulation of urea cycle flux by allosteric activation (NAG activation of CPS1; arginine activation of NAGS). (fernandez2015usingrecombinanthuman pages 34-37, shi2015thenacetylglutamatesynthase pages 3-6) • Astrocyte glutamine biosynthetic process as compensatory ammonia detoxification in brain, leading to osmotic imbalance/cytotoxic edema. (haberle2020primaryhyperammonaemiacurrent pages 3-4, redant2021managementoflate pages 1-3) • Glutamatergic/NMDA-mediated neurotransmission perturbation and mitochondrial dysfunction in brain during hyperammonemia. (haberle2020primaryhyperammonaemiacurrent pages 3-4)

5) Cellular components (subcellular localization) • Mitochondrial matrix: NAGS localization in liver and intestine; CPS1 abundance in liver mitochondria. (shi2015thenacetylglutamatesynthase pages 3-6, fernandez2015usingrecombinanthuman pages 37-41) • Blood–brain barrier: ammonia crosses into CNS. (haberle2020primaryhyperammonaemiacurrent pages 3-4)

6) Disease progression and sequence of events Initiation/trigger • Genetic NAGS deficiency (autosomal recessive) leads to insufficient NAG production, with susceptibility to hyperammonemia during high nitrogen load or catabolic stress. (kenneson2020presentationandmanagement pages 1-3)

Biochemical progression 1) Reduced NAG → CPS1 underactivation (“inactive without NAG”) → reduced carbamoyl phosphate formation and urea cycle throughput. (fernandez2015usingrecombinanthuman pages 34-37) 2) Systemic ammonia rises (hyperammonemia) with typical proximal-UCD amino-acid patterns (often elevated glutamine, decreased citrulline, normal orotic acid). (kenneson2020presentationandmanagement pages 1-3) 3) CNS toxicity: ammonia crosses BBB; astrocyte glutamine accumulation → astrocyte swelling → cerebral edema; neurotransmission and mitochondrial dysfunction contribute to encephalopathy/seizures. (haberle2020primaryhyperammonaemiacurrent pages 3-4, redant2021managementoflate pages 1-3)

Clinical phases (pragmatic) • Neonatal-onset hyperammonemic encephalopathy is common (majority present in neonatal period), but later-onset presentations occur, including adult-onset in some cases. (kenneson2020presentationandmanagement pages 1-3, cavicchi2018lateonsetnacetylglutamatesynthase pages 1-3) • Acute crises recur particularly with illness, catabolism, dietary protein load, or interruptions in therapy. (kenneson2020presentationandmanagement pages 1-3, singh2024theefficacyof pages 1-2)

7) Phenotypic manifestations (HP-oriented) and mechanistic links Key phenotypes • Hyperammonemia (core biochemical/clinical trait). (haberle2020primaryhyperammonaemiacurrent pages 3-4) • Encephalopathy, seizures, and cerebral edema driven by brain glutamine-mediated osmotic swelling and neurotransmission/mitochondrial effects. (haberle2020primaryhyperammonaemiacurrent pages 3-4, redant2021managementoflate pages 1-3) • Biochemical profile consistent with proximal urea cycle block: elevated plasma glutamine and decreased/low citrulline; urine orotic acid typically normal (but can vary). (kenneson2020presentationandmanagement pages 1-3, singh2024theefficacyof pages 2-4)

Clinical example (neonatal case) A molecularly confirmed neonatal case showed ammonia rising to 1194 µM with “elevated glutamine and glycine” and “undetectable citrulline,” consistent with a proximal urea cycle defect. (kaabi2016nacetylglutamatesynthasedeficiency pages 1-2)

8) Recent developments and latest research (prioritizing 2023–2024) 8.1 2024 mechanistic advance: functional assessment of human NAGS missense variants Gougeard et al. (May 2024) provide a high-resolution genotype-to-mechanism mapping for NAGSD variants using stabilized recombinant human NAGS, identifying multiple mechanistic classes (loss of arginine activation, increased Km for glutamate, misfolding, etc.) and explicitly arguing this approach “outperforms” reliance on bacterial surrogates or in silico prediction for therapeutic guidance. (gougeard2024useofpure pages 1-2, gougeard2024useofpure pages 9-11)

8.2 2024 clinical care advance: carbamylglutamate efficacy and nutrition management Singh et al. (Apr 2024) added seven North American cases and reported that “All patients responded well to carbamylglutamate therapy, as indicated by normalization of plasma ammonia and citrulline, as well as urine orotic acid” when abnormal. (singh2024theefficacyof pages 1-2) They also report that disruptions in drug access can directly precipitate hyperammonemia and poor outcomes, making medication continuity a major implementation priority. (singh2024theefficacyof pages 1-2)

9) Current applications and real-world implementations 9.1 Diagnosis (biochemical + molecular) Biochemical suspicion relies on hyperammonemia with a proximal-UCD amino-acid pattern: “elevated glutamine and decreased citrulline” with urine orotic acid “not elevated.” (kenneson2020presentationandmanagement pages 6-7) Because NAGSD and CPS1 deficiency are clinically indistinguishable and lack “reliable differential biomarkers,” confirmatory genetic testing is critical. (gougeard2024useofpure pages 1-2) A therapeutic trial of carbamylglutamate is recommended for patients with unexplained hyperammonemia: “a therapeutic trial be initiated for any patient with unexplained hyperammonemia.” (kenneson2020presentationandmanagement pages 6-7)

Newborn screening NAGS deficiency is not reliably captured by newborn screening markers; limitations include “instability of glutamine and low specificity and sensitivity of reduced citrulline levels,” and neonatal-onset disease may present before results are available. (kenneson2020presentationandmanagement pages 7-9)

9.2 Acute management Acute hyperammonemia care commonly includes nitrogen scavengers (benzoate, phenylacetate) plus carbamylglutamate in suspected NAGS deficiency. (singh2024theefficacyof pages 1-2) Severe crises may require extracorporeal detoxification (dialysis/CVVH), as illustrated by neonatal and broader UCD management reports. (singh2024theefficacyof pages 4-5, mcnutt2024fatalconsequencesof pages 2-3)

9.3 Targeted disease-modifying therapy: carglumic acid (N-carbamylglutamate) Mechanism Carbamylglutamate (carglumic acid) is a synthetic NAG analog that “activates” CPS1, bypassing deficient NAGS and restoring urea cycle flux. (singh2024theefficacyof pages 1-2) Clinical effect In the 2024 case series, ammonia normalization sometimes required carbamylglutamate after partial response to scavengers; long-term therapy enabled protein liberalization in most patients. (singh2024theefficacyof pages 2-4) Dosing (reported ranges) • Maintenance dosing in case literature: 100–200 mg/kg/day in 3–4 divided doses, with down-titration possible (as low as 10–15 mg/kg/day) to maintain ammonia control (older literature summary). (kaabi2016nacetylglutamatesynthasedeficiency pages 4-4) • In the 2024 series, the lowest daily dose used without recurrent hyperammonemia was 43 mg/kg/day (noting individualization and uncertainty in “maximum safe protein intake”). (singh2024theefficacyof pages 2-4)

Implementation barriers Medication access interruptions are a major, documented cause of preventable decompensation. Singh et al. describe hyperammonemic episodes after disruptions due to insurance authorization and language barriers, and after seizures limited caregivers’ ability to administer medication. (singh2024theefficacyof pages 1-2) Earlier reports highlight limited drug availability in some settings (e.g., tertiary center) affecting treatment continuity. (kaabi2016nacetylglutamatesynthasedeficiency pages 1-2) Broader urea-cycle care also demonstrates that limited health literacy and fragmented access to metabolic supplies/medications can be fatal (case example in another UCD subtype). (mcnutt2024fatalconsequencesof pages 2-3)

10) Relevant statistics and data (recent studies prioritized) Key disease statistics • Incidence: “less than one in 2,000,000 live births.” (Apr 2024) (singh2024theefficacyof pages 1-2) • Presentation age: a review of 98 cases found 58% presented before 1 month of age. (singh2024theefficacyof pages 1-2)

Biomarker/response data (2024 series) Singh et al. report NAGS deficiency presentations with very high ammonia (example 1257 µmol/L), elevated glutamine at presentation in all cases, variable citrulline, and mildly elevated urine orotic acid in some; and that response to carbamylglutamate included normalization of ammonia/citrulline/orotic acid where abnormal. (singh2024theefficacyof pages 2-4, singh2024theefficacyof media 8fe48c65)

Variant mechanism statistics (2024 mechanistic study) Gougeard et al. report that altered arginine activation is common among variants: e.g., “9 of 17 enzymatically active variants ... not activated” by arginine in their assays, and increased Km for glutamate was frequent among active variants. (gougeard2024useofpure pages 12-14, gougeard2024useofpure pages 11-12)

11) Expert opinions and authoritative analyses Guideline perspective The 2019 revision of urea cycle disorder guidelines emphasizes ongoing “under-recognition and delayed diagnosis” despite effective therapies, and aims to harmonize best practices across centers. (haberle2019suggestedguidelinesfor pages 1-3) Mechanistic/therapeutic guidance perspective (2024) Gougeard et al. emphasize that because NAGSD is “cured by substitutive therapy” with N-carbamyl-L-glutamate while CPS1D may require transplantation, accurate molecular diagnosis and functional interpretation of variants are central to therapeutic decision-making. (gougeard2024useofpure pages 1-2)

12) Knowledge-base–ready structured annotations 12.1 Pathophysiology summary (narrative for KB entry) NAGSD is caused by biallelic pathogenic variants in NAGS leading to reduced mitochondrial NAG production in liver (and intestine). NAG is the essential allosteric activator required for CPS1 activity; without NAG, CPS1 is inactive and the urea cycle fails to convert ammonia to urea. Systemic hyperammonemia results, often with elevated glutamine and low/variable citrulline and typically normal urine orotic acid. Ammonia crosses the blood–brain barrier; astrocytes convert ammonia to glutamine, which acts as an osmolyte and drives astrocyte swelling and cerebral edema, with downstream neurotransmission and mitochondrial dysfunction causing encephalopathy and seizures. Targeted therapy with N-carbamyl-L-glutamate (carglumic acid) restores CPS1 activation and can prevent crises, but outcomes depend strongly on early recognition and uninterrupted access to therapy. (fernandez2015usingrecombinanthuman pages 34-37, singh2024theefficacyof pages 1-2, haberle2020primaryhyperammonaemiacurrent pages 3-4)

12.2 Gene/protein annotations (HGNC/GO-style) • NAGS (HGNC symbol: NAGS): enzyme catalyzing N-acetylglutamate synthesis from acetyl-CoA and glutamate; localized to mitochondrial matrix in liver/intestine; regulated by L-arginine. (shi2015thenacetylglutamatesynthase pages 3-6, haskins2016effectofarginine pages 1-2) • CPS1: urea-cycle initiating enzyme requiring NAG as essential activator/cofactor. (shi2015thenacetylglutamatesynthase pages 1-3, fernandez2015usingrecombinanthuman pages 34-37)

12.3 Candidate GO biological processes (labels; IDs not provided in sources) • Urea cycle / ammonia detoxification (disrupted). (singh2024theefficacyof pages 1-2) • N-acetylglutamate biosynthesis (disrupted). (shi2015thenacetylglutamatesynthase pages 1-3) • Allosteric regulation of carbamoyl phosphate synthetase activity (disrupted due to absent NAG). (fernandez2015usingrecombinanthuman pages 34-37) • Astrocyte glutamine biosynthesis and osmotic homeostasis (pathogenic in crisis). (haberle2020primaryhyperammonaemiacurrent pages 3-4)

12.4 Cellular components (labels) • Mitochondrial matrix (primary site of NAGS/CPS1 function). (shi2015thenacetylglutamatesynthase pages 3-6, fernandez2015usingrecombinanthuman pages 37-41) • Blood–brain barrier (ammonia transfer). (haberle2020primaryhyperammonaemiacurrent pages 3-4)

12.5 Phenotype associations (HP-style labels) • Hyperammonemia; hyperammonemic encephalopathy; cerebral edema; seizures; elevated glutamine; decreased/low citrulline; respiratory alkalosis (reported in some). (haberle2020primaryhyperammonaemiacurrent pages 3-4, kenneson2020presentationandmanagement pages 6-7)

12.6 Cell type involvement (CL-style labels) • Hepatocyte (periportal hepatocytes emphasized for urea cycle). (fernandez2015usingrecombinanthuman pages 37-41) • Astrocyte (glutamine synthesis, swelling). (haberle2020primaryhyperammonaemiacurrent pages 3-4)

12.7 Anatomical locations (UBERON-style labels) • Liver; intestine; brain. (shi2015thenacetylglutamatesynthase pages 3-6, haberle2020primaryhyperammonaemiacurrent pages 3-4)

12.8 Chemical entities (CHEBI-style labels) • N-acetyl-L-glutamate (NAG); ammonia; glutamine; citrulline; acetyl-CoA; L-glutamate; N-carbamyl-L-glutamate (carglumic acid). (shi2015thenacetylglutamatesynthase pages 1-3, kaabi2016nacetylglutamatesynthasedeficiency pages 4-4)

13) Evidence items (PMIDs when available; otherwise DOI/URL) Note: Several key 2024 sources retrieved here (Singh 2024; Gougeard 2024) were processed via DOI-linked full text and the PMIDs were not explicitly present in the extracted text. Where PMIDs were available in retrieved evidence, they are listed.

Primary/Recent (2023–2024 prioritized) • Singh RH et al. “The efficacy of Carbamylglutamate impacts the nutritional management of patients with N-Acetylglutamate synthase deficiency.” Orphanet J Rare Dis. Apr 2024. DOI:10.1186/s13023-024-03167-0. URL:https://doi.org/10.1186/s13023-024-03167-0. (singh2024theefficacyof pages 2-4) • Gougeard N et al. “Use of pure recombinant human enzymes to assess the disease-causing potential of missense mutations in urea cycle disorders, applied to N-acetylglutamate synthase deficiency.” J Inherit Metab Dis. May 2024. DOI:10.1002/jimd.12747. URL:https://doi.org/10.1002/jimd.12747. (gougeard2024useofpure pages 1-2) • McNutt MC. “Fatal consequences of limited health literacy in a patient with a rare metabolic disease.” Mol Genet Metab Rep. Jul 2024. DOI:10.1016/j.ymgmr.2024.101121. URL:https://doi.org/10.1016/j.ymgmr.2024.101121. (mcnutt2024fatalconsequencesof pages 2-3)

Guidelines / authoritative reviews • Häberle J et al. “Suggested guidelines for the diagnosis and management of urea cycle disorders: First revision.” J Inherit Metab Dis. May 2019. DOI:10.1002/jimd.12100. URL:https://doi.org/10.1002/jimd.12100. (haberle2019suggestedguidelinesfor pages 1-3) • Häberle J. “Primary Hyperammonaemia: Current Diagnostic and Therapeutic Strategies.” J Mother Child. Jun 2020. DOI:10.34763/jmotherandchild.20202402si.2015.000006. URL:https://doi.org/10.34763/jmotherandchild.20202402si.2015.000006. (haberle2020primaryhyperammonaemiacurrent pages 3-4) • Kenneson A, Singh RH. “Presentation and management of N-acetylglutamate synthase deficiency: a review of the literature.” Orphanet J Rare Dis. Oct 2020. DOI:10.1186/s13023-020-01560-z. URL:https://doi.org/10.1186/s13023-020-01560-z. (kenneson2020presentationandmanagement pages 1-3)

Mechanistic background • Shi D et al. “The N-Acetylglutamate Synthase Family: Structures, Function and Mechanisms.” Int J Mol Sci. Jun 2015. DOI:10.3390/ijms160613004. URL:https://doi.org/10.3390/ijms160613004. (shi2015thenacetylglutamatesynthase pages 1-3) • Haskins N et al. “Effect of arginine on oligomerization and stability of N-acetylglutamate synthase.” Sci Rep. Dec 2016. DOI:10.1038/srep38711. URL:https://doi.org/10.1038/srep38711. (haskins2016effectofarginine pages 1-2) • Savy N et al. “Acute pediatric hyperammonemia: current diagnosis and management strategies.” Hepatic Med. Sep 2018. DOI:10.2147/HMER.S140711. URL:https://doi.org/10.2147/hmer.s140711. (savy2018acutepediatrichyperammonemia pages 1-2)

Clinical exemplar • Al Kaabi EH, El-Hattab AW. “N-acetylglutamate synthase deficiency: Novel mutation associated with neonatal presentation…” Mol Genet Metab Rep. Sep 2016. DOI:10.1016/j.ymgmr.2016.08.004. URL:https://doi.org/10.1016/j.ymgmr.2016.08.004. (kaabi2016nacetylglutamatesynthasedeficiency pages 1-2)

Visual evidence (from 2024 case series) • Singh et al. Table summarizing biochemical findings and treatment/outcomes, including ammonia/citrulline/orotic acid and responses to carbamylglutamate. (singh2024theefficacyof media 8fe48c65, singh2024theefficacyof media adfabe34)

14) Limitations of this synthesis (transparency) • PMIDs were not consistently present in the retrieved full-text extractions for some 2024 papers; this report therefore provides DOIs/URLs for those key sources and includes PMIDs only where available from OpenTargets disease-target evidence or where explicitly present in extracted text. (erdal2025aminoacidmetabolism pages 10-12)

References

  1. (gougeard2024useofpure pages 1-2): Nadine Gougeard, Enea Sancho‐Vaello, M. Leonor Fernández‐Murga, Borja Martínez‐Sinisterra, Badr Loukili‐Hassani, Johannes Häberle, Clara Marco‐Marín, and Vicente Rubio. Use of pure recombinant human enzymes to assess the disease‐causing potential of missense mutations in urea cycle disorders, applied to n‐acetylglutamate synthase deficiency. Journal of Inherited Metabolic Disease, 47:1194-1212, May 2024. URL: https://doi.org/10.1002/jimd.12747, doi:10.1002/jimd.12747. This article has 2 citations and is from a peer-reviewed journal.

  2. (singh2024theefficacyof pages 1-2): Rani H. Singh, Marie-Hélène Bourdages, Angela Kurtz, Erin MacLoed, Chelsea Norman, Suzanne Ratko, Sandra C. van Calcar, and Aileen Kenneson. The efficacy of carbamylglutamate impacts the nutritional management of patients with n-acetylglutamate synthase deficiency. Orphanet Journal of Rare Diseases, Apr 2024. URL: https://doi.org/10.1186/s13023-024-03167-0, doi:10.1186/s13023-024-03167-0. This article has 8 citations and is from a peer-reviewed journal.

  3. (erdal2025aminoacidmetabolism pages 10-12): Ranya Erdal, Kıvanç Birsoy, and Gokhan Unlu. Amino acid metabolism in liver mitochondria: from homeostasis to disease. Metabolites, 15:446, Jul 2025. URL: https://doi.org/10.3390/metabo15070446, doi:10.3390/metabo15070446. This article has 2 citations.

  4. (kaabi2016nacetylglutamatesynthasedeficiency pages 1-2): Eiman H. Al Kaabi and Ayman W. El-Hattab. N-acetylglutamate synthase deficiency: novel mutation associated with neonatal presentation and literature review of molecular and phenotypic spectra. Sep 2016. URL: https://doi.org/10.1016/j.ymgmr.2016.08.004, doi:10.1016/j.ymgmr.2016.08.004. This article has 17 citations.

  5. (kenneson2020presentationandmanagement pages 1-3): Aileen Kenneson and Rani H. Singh. Presentation and management of n-acetylglutamate synthase deficiency: a review of the literature. Orphanet Journal of Rare Diseases, Oct 2020. URL: https://doi.org/10.1186/s13023-020-01560-z, doi:10.1186/s13023-020-01560-z. This article has 23 citations and is from a peer-reviewed journal.

  6. (shi2015thenacetylglutamatesynthase pages 1-3): Dashuang Shi, Norma Allewell, and Mendel Tuchman. The n-acetylglutamate synthase family: structures, function and mechanisms. International Journal of Molecular Sciences, 16:13004-13022, Jun 2015. URL: https://doi.org/10.3390/ijms160613004, doi:10.3390/ijms160613004. This article has 41 citations.

  7. (fernandez2015usingrecombinanthuman pages 37-41): CARMEN DÍEZ FERNÁNDEZ. USING RECOMBINANT HUMAN CARBAMOYL PHOSPHATE SYNTHETASE 1 (CPS1) FOR STUDYING THIS ENZYME'S FUNCTION, REGULATION, PATHOLOGY AND STRUCTURE. PhD thesis, Universitat Politecnica de Valencia, 2015. URL: https://doi.org/10.4995/thesis/10251/52855, doi:10.4995/thesis/10251/52855.

  8. (fernandez2015usingrecombinanthuman pages 34-37): CARMEN DÍEZ FERNÁNDEZ. USING RECOMBINANT HUMAN CARBAMOYL PHOSPHATE SYNTHETASE 1 (CPS1) FOR STUDYING THIS ENZYME'S FUNCTION, REGULATION, PATHOLOGY AND STRUCTURE. PhD thesis, Universitat Politecnica de Valencia, 2015. URL: https://doi.org/10.4995/thesis/10251/52855, doi:10.4995/thesis/10251/52855.

  9. (shi2015thenacetylglutamatesynthase pages 3-6): Dashuang Shi, Norma Allewell, and Mendel Tuchman. The n-acetylglutamate synthase family: structures, function and mechanisms. International Journal of Molecular Sciences, 16:13004-13022, Jun 2015. URL: https://doi.org/10.3390/ijms160613004, doi:10.3390/ijms160613004. This article has 41 citations.

  10. (haberle2020primaryhyperammonaemiacurrent pages 3-4): Johannes Häberle. Primary hyperammonaemia: current diagnostic and therapeutic strategies. Journal of Mother and Child, 24:32-38, Jun 2020. URL: https://doi.org/10.34763/jmotherandchild.20202402si.2015.000006, doi:10.34763/jmotherandchild.20202402si.2015.000006. This article has 22 citations.

  11. (redant2021managementoflate pages 1-3): S. Redant, A. Empain, A. Mugisha, P. Kamgang, R. Attou, P. M. Honoré, and D. De Bels. Management of late onset urea cycle disorders—a remaining challenge for the intensivist? Annals of Intensive Care, Jan 2021. URL: https://doi.org/10.1186/s13613-020-00797-y, doi:10.1186/s13613-020-00797-y. This article has 41 citations and is from a peer-reviewed journal.

  12. (gougeard2024useofpure pages 2-4): Nadine Gougeard, Enea Sancho‐Vaello, M. Leonor Fernández‐Murga, Borja Martínez‐Sinisterra, Badr Loukili‐Hassani, Johannes Häberle, Clara Marco‐Marín, and Vicente Rubio. Use of pure recombinant human enzymes to assess the disease‐causing potential of missense mutations in urea cycle disorders, applied to n‐acetylglutamate synthase deficiency. Journal of Inherited Metabolic Disease, 47:1194-1212, May 2024. URL: https://doi.org/10.1002/jimd.12747, doi:10.1002/jimd.12747. This article has 2 citations and is from a peer-reviewed journal.

  13. (gougeard2024useofpure pages 12-14): Nadine Gougeard, Enea Sancho‐Vaello, M. Leonor Fernández‐Murga, Borja Martínez‐Sinisterra, Badr Loukili‐Hassani, Johannes Häberle, Clara Marco‐Marín, and Vicente Rubio. Use of pure recombinant human enzymes to assess the disease‐causing potential of missense mutations in urea cycle disorders, applied to n‐acetylglutamate synthase deficiency. Journal of Inherited Metabolic Disease, 47:1194-1212, May 2024. URL: https://doi.org/10.1002/jimd.12747, doi:10.1002/jimd.12747. This article has 2 citations and is from a peer-reviewed journal.

  14. (singh2024theefficacyof pages 2-4): Rani H. Singh, Marie-Hélène Bourdages, Angela Kurtz, Erin MacLoed, Chelsea Norman, Suzanne Ratko, Sandra C. van Calcar, and Aileen Kenneson. The efficacy of carbamylglutamate impacts the nutritional management of patients with n-acetylglutamate synthase deficiency. Orphanet Journal of Rare Diseases, Apr 2024. URL: https://doi.org/10.1186/s13023-024-03167-0, doi:10.1186/s13023-024-03167-0. This article has 8 citations and is from a peer-reviewed journal.

  15. (haskins2016effectofarginine pages 1-2): N. Haskins, Amy Mumo, P. H. Brown, M. Tuchman, H. Morizono, and L. Caldovic. Effect of arginine on oligomerization and stability of n-acetylglutamate synthase. Scientific Reports, Dec 2016. URL: https://doi.org/10.1038/srep38711, doi:10.1038/srep38711. This article has 9 citations and is from a peer-reviewed journal.

  16. (savy2018acutepediatrichyperammonemia pages 1-2): Nadia Savy, David Brossier, Catherine Brunel-Guitton, Laurence Ducharme-Crevier, Geneviève Du Pont-Thibodeau, and Philippe Jouvet. Acute pediatric hyperammonemia: current diagnosis and management strategies. Hepatic Medicine : Evidence and Research, 10:105-115, Sep 2018. URL: https://doi.org/10.2147/hmer.s140711, doi:10.2147/hmer.s140711. This article has 105 citations.

  17. (cavicchi2018lateonsetnacetylglutamatesynthase pages 1-3): Catia Cavicchi, Chiara Chilleri, Antonella Fioravanti, Lorenzo Ferri, Francesco Ripandelli, Cinzia Costa, Paolo Calabresi, Paolo Prontera, Francesca Pochiero, Elisabetta Pasquini, Silvia Funghini, Giancarlo La Marca, Maria Donati, and Amelia Morrone. Late-onset n-acetylglutamate synthase deficiency: report of a paradigmatic adult case presenting with headaches and review of the literature. International Journal of Molecular Sciences, 19:345, Jan 2018. URL: https://doi.org/10.3390/ijms19020345, doi:10.3390/ijms19020345. This article has 11 citations.

  18. (gougeard2024useofpure pages 9-11): Nadine Gougeard, Enea Sancho‐Vaello, M. Leonor Fernández‐Murga, Borja Martínez‐Sinisterra, Badr Loukili‐Hassani, Johannes Häberle, Clara Marco‐Marín, and Vicente Rubio. Use of pure recombinant human enzymes to assess the disease‐causing potential of missense mutations in urea cycle disorders, applied to n‐acetylglutamate synthase deficiency. Journal of Inherited Metabolic Disease, 47:1194-1212, May 2024. URL: https://doi.org/10.1002/jimd.12747, doi:10.1002/jimd.12747. This article has 2 citations and is from a peer-reviewed journal.

  19. (kenneson2020presentationandmanagement pages 6-7): Aileen Kenneson and Rani H. Singh. Presentation and management of n-acetylglutamate synthase deficiency: a review of the literature. Orphanet Journal of Rare Diseases, Oct 2020. URL: https://doi.org/10.1186/s13023-020-01560-z, doi:10.1186/s13023-020-01560-z. This article has 23 citations and is from a peer-reviewed journal.

  20. (kenneson2020presentationandmanagement pages 7-9): Aileen Kenneson and Rani H. Singh. Presentation and management of n-acetylglutamate synthase deficiency: a review of the literature. Orphanet Journal of Rare Diseases, Oct 2020. URL: https://doi.org/10.1186/s13023-020-01560-z, doi:10.1186/s13023-020-01560-z. This article has 23 citations and is from a peer-reviewed journal.

  21. (singh2024theefficacyof pages 4-5): Rani H. Singh, Marie-Hélène Bourdages, Angela Kurtz, Erin MacLoed, Chelsea Norman, Suzanne Ratko, Sandra C. van Calcar, and Aileen Kenneson. The efficacy of carbamylglutamate impacts the nutritional management of patients with n-acetylglutamate synthase deficiency. Orphanet Journal of Rare Diseases, Apr 2024. URL: https://doi.org/10.1186/s13023-024-03167-0, doi:10.1186/s13023-024-03167-0. This article has 8 citations and is from a peer-reviewed journal.

  22. (mcnutt2024fatalconsequencesof pages 2-3): Markey C. McNutt. Fatal consequences of limited health literacy in a patient with a rare metabolic disease. Molecular Genetics and Metabolism Reports, Jul 2024. URL: https://doi.org/10.1016/j.ymgmr.2024.101121, doi:10.1016/j.ymgmr.2024.101121. This article has 0 citations.

  23. (kaabi2016nacetylglutamatesynthasedeficiency pages 4-4): Eiman H. Al Kaabi and Ayman W. El-Hattab. N-acetylglutamate synthase deficiency: novel mutation associated with neonatal presentation and literature review of molecular and phenotypic spectra. Sep 2016. URL: https://doi.org/10.1016/j.ymgmr.2016.08.004, doi:10.1016/j.ymgmr.2016.08.004. This article has 17 citations.

  24. (singh2024theefficacyof media 8fe48c65): Rani H. Singh, Marie-Hélène Bourdages, Angela Kurtz, Erin MacLoed, Chelsea Norman, Suzanne Ratko, Sandra C. van Calcar, and Aileen Kenneson. The efficacy of carbamylglutamate impacts the nutritional management of patients with n-acetylglutamate synthase deficiency. Orphanet Journal of Rare Diseases, Apr 2024. URL: https://doi.org/10.1186/s13023-024-03167-0, doi:10.1186/s13023-024-03167-0. This article has 8 citations and is from a peer-reviewed journal.

  25. (gougeard2024useofpure pages 11-12): Nadine Gougeard, Enea Sancho‐Vaello, M. Leonor Fernández‐Murga, Borja Martínez‐Sinisterra, Badr Loukili‐Hassani, Johannes Häberle, Clara Marco‐Marín, and Vicente Rubio. Use of pure recombinant human enzymes to assess the disease‐causing potential of missense mutations in urea cycle disorders, applied to n‐acetylglutamate synthase deficiency. Journal of Inherited Metabolic Disease, 47:1194-1212, May 2024. URL: https://doi.org/10.1002/jimd.12747, doi:10.1002/jimd.12747. This article has 2 citations and is from a peer-reviewed journal.

  26. (haberle2019suggestedguidelinesfor pages 1-3): Johannes Häberle, Alberto Burlina, Anupam Chakrapani, Marjorie Dixon, Daniela Karall, Martin Lindner, Hanna Mandel, Diego Martinelli, Guillem Pintos‐Morell, René Santer, Anastasia Skouma, Aude Servais, Galit Tal, Vicente Rubio, Martina Huemer, and Carlo Dionisi‐Vici. Suggested guidelines for the diagnosis and management of urea cycle disorders: first revision. Journal of Inherited Metabolic Disease, 42:1192-1230, May 2019. URL: https://doi.org/10.1002/jimd.12100, doi:10.1002/jimd.12100. This article has 544 citations and is from a peer-reviewed journal.

  27. (singh2024theefficacyof media adfabe34): Rani H. Singh, Marie-Hélène Bourdages, Angela Kurtz, Erin MacLoed, Chelsea Norman, Suzanne Ratko, Sandra C. van Calcar, and Aileen Kenneson. The efficacy of carbamylglutamate impacts the nutritional management of patients with n-acetylglutamate synthase deficiency. Orphanet Journal of Rare Diseases, Apr 2024. URL: https://doi.org/10.1186/s13023-024-03167-0, doi:10.1186/s13023-024-03167-0. This article has 8 citations and is from a peer-reviewed journal.