Natural history of epilepsy in argininosuccinic aciduria provides new insights into pathophysiology
Bibliographic record
Abstract
ABSTRACT Introduction Argininosuccinate lyase is integral to the urea cycle, which enables nitrogen waste and biosynthesis of arginine, a precursor of nitric oxide. Inherited argininosuccinate lyase deficiency causes argininosuccinic aciduria, the second most common urea cycle defect and an inherited model of systemic nitric oxide deficiency. Patients present with developmental delay, epilepsy and movement disorder. Here we aim to characterise epilepsy, a common and neurodebilitating complication in argininosuccinic aciduria. Patients and Methods We conducted a retrospective study in seven tertiary metabolic centres in the UK, Italy and Canada from 2020 to 2022 to assess the phenotype of epilepsy in ASA and correlate it with clinical, biochemical, radiological and electroencephalographic data. Results Thirty-seven patients aged 1 to 31 years old were included. Twenty-two (60%) patients presented epilepsy. Median age at epilepsy-onset was 24 months. Generalized tonic clonic and focal seizures were most common in early-onset patients whilst atypical absences were predominant in late-onset patients. Seventeen patients (77%) required antiseizure medications and 6 (27%) had partially controlled or refractory epilepsy. Epileptic patients presented with a severe neurodebilitating disease with higher rates of speech delay ( p =0.04) and autism spectrum disorders ( p =0.01) and more frequent arginine supplementation ( p =0.01) compared to non-epileptic patients. Neonatal seizures were not associated with a higher risk of developing epilepsy. Biomarkers of ureagenesis did not differ between epileptic and non-epileptic patients. Epilepsy-onset in early infancy ( p =0.05) and electroencephalographic background asymmetry ( p =0.0007) were significant predictors of partially controlled or refractory epilepsy. Conclusions Epilepsy in argininosuccinic aciduria is frequent, polymorphic, associated with more frequent neurodevelopmental complications. We identified prognostic factors for pharmacoresistance in epilepsy. This study does not support defective ureagenesis as prominent in the pathophysiology of epilepsy but suggests roles of arginine toxicity and central dopamine deficiency. Key Points Epilepsy in ASA is frequent, polymorphic, occurring in early childhood and associated with a more severe neurodevelopmental phenotype. Early-onset epilepsy and electroencephalographic background asymmetry are prognostic for pharmaco-resistance of epilepsy in ASA. Hyperammonaemia is suggested not to be the primary pathophysiological mechanism for epileptogenesis in ASA. Central dopamine deficiency is suggested to have a role in pathophysiology of epilepsy in ASA. Arginine-related neurotoxicity is suggested to be associated with increased in frequency and severity of epilepsy in ASA.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".