Natural History of Succinic Semialdehyde Dehydrogenase Deficiency through Adulthood (P5.159)
Bibliographic record
Abstract
Objective: The natural history of SSADH deficiency in adulthood is poorly unknown; we wished to elucidate the clinical manifestations of the disease later in life. Background: Succinic semialdehyde dehydrogenase (SSADH) deficiency, an autosomal recessive inborn error of GABA metabolism, leads to accumulation of 4-hydroxybutyric acid (GHB). Approximately 450 patients have been identified, with a typical phenotype of developmental delay starting in late infancy and a subsequent non-progressive encephalopathy with cognitive deficiency, expressive language impairment, ataxia, and epilepsy. Given the non-specific symptoms, undiagnosed cases are likely. Few adult patients are reported. Methods: A 63-year-old man with longstanding intellectual disability was diagnosed with SSADH deficiency following hospitalization for progressive decline, escalating seizures, and prolonged periods of altered consciousness. We present a detailed review of his clinical course and reviewed our SSADH deficiency database adult cohort to derive natural history information. Results: Of 95 patients in the database for whom age at diagnosis is recorded, there are 40 individuals currently aged 18 years or above. Only three patients were diagnosed after age 18 years. Of 25 adults for whom data is available after age 18, 60[percnt] have a history of epilepsy. Predominant seizure types are generalized tonic-clonic, absence, and myoclonic. EEGs showed background slowing or generalized epileptiform discharges in 2/3 of adults for whom EEG data was collected. History of psychiatric symptoms was prominent with frequent anxiety, sleep disturbances, and obsessive-compulsive disorder. Conclusions: We identified SSADH deficiency patients in our database over age 18 years of age following identification and review of a patient diagnosed in the seventh decade of life. The illness had a progressive course with escalating seizures in the index case with fatality at age 63. Diagnosis in adulthood is rare. Epilepsy is more common in the adult than pediatric SSADH deficiency cohort; neuropsychiatric morbidity remains prominent.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".