Phenotypic Features and Genetic Findings in Sacsin-Related Autosomal Recessive Ataxia in Tunisia
Bibliographic record
Abstract
BACKGROUND: Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a clinically homogenous disorder reported in Quebec caused by mutations in the SACS gene (chromosome 13q12). Recently, we identified a Tunisian kindred demonstrating linkage to the ARSACS locus. OBJECTIVE: To report clinical, neurophysiological, and nerve biopsy findings in patients with autosomal recessive cerebellar ataxia related to the SACS gene in Tunisia. PATIENTS AND METHODS: Genetic linkage analysis of patients with early-onset autosomal recessive cerebellar ataxia allowed the identification of 4 families from which 18 patients demonstrated linkage to the ARSACS locus. The patients were evaluated according to the International Cooperative Ataxia Rating Scale. Peripheral nerve conduction, sensory evoked potentials, and nerve biopsy were performed in most patients. RESULTS: The mean age at onset was 4.5 years. The clinical phenotype was stereotyped and associated with a progressive cerebellar syndrome, a pyramidal syndrome with brisk knee reflexes, and Babinski sign and absent ankle reflexes. The course of the disease varied among patients. Sensory evoked potentials showed severe posterior column involvement. Peripheral nerve investigations demonstrated axonal and demyelinating neuropathy. Four mutations, 2 missense and 2 nonsense, were found. CONCLUSION: In Tunisia, autosomal recessive cerebellar ataxia related to the SACS gene demonstrated a homogenous phenotype and heterogeneous allelic mutations.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".