The ARSACS phenotype can include supranuclear gaze palsy and skin lipofuscin deposits
Bibliographic record
Abstract
The autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) phenotype was first characterised in patients from Quebec, all of whom had young onset spasticity and gait ataxia. Other features included distal amyotrophy, extensor plantar responses, cerebellar speech, saccadic intrusion in smooth pursuit and hypermyelinated retinal nerve fibres.1 Seven percent had seizures. Spasticity and ataxia were progressive. Electromyography showed denervation. Nerve conduction studies showed reduced conduction velocities with absent sensory action potentials. Nerve biopsy showed a lack of large myelinated axons.2 Subsequent analysis of this cohort has shown two founder mutations in the SACS gene—c.6594delT and c.5254C>T.3 Identification of mutations in SACS as the cause of ARSACS facilitated the detection of further cases worldwide, revealing greater phenotypic variation. Vermeer et al screened 43 patients presenting with ataxia prior to age 25 (suggesting an autosomal recessive cause4), finding 16 patients with SACS mutations.5 One patient had onset aged 12, two showed dystonia. Baets et al 6 screened 85 patients with at least two of cerebellar ataxia, spasticity and peripheral neuropathy, finding 18 different mutations. In five of these patients, disease onset was at over 20 years, one patient had no signs of peripheral neuropathy, several patients presented primarily with peripheral neuropathy and only one had hypermyelinated retinal nerve fibres using standard fundoscopy. Two patients had mild cognitive impairment and one epilepsy. Breckpot et al 7 detected a deletion of SACS combined with a hemizygous SACS mutation causing early-onset ARSACS with hearing impairment. We describe a 37-year-old patient who first walked at 23 months. Aged seven, he had cerebellar ataxia and brisk reflexes in all limbs. Cognitive function has been normal but ataxia and spasticity have progressed. He also developed epilepsy, myoclonus and …
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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) | 0.002 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.008 | 0.002 |
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".