Mutations in <i>SACS</i> cause atypical and late-onset forms of ARSACS
Bibliographic record
Abstract
BACKGROUND: Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a complex neurodegenerative disorder caused by mutations in SACS. The phenotype consists of a childhood-onset triad of cerebellar ataxia, peripheral neuropathy, and pyramidal tract signs. OBJECTIVE: To provide more insight into the prevalence of SACS mutations and the variability of the associated phenotype. METHODS: Mutation screening of SACS by direct sequencing and multiplex amplicon quantification for detection of intragenic copy number variations in a cohort of 85 index patients with phenotypes suggestive for ARSACS. Additional short tandem repeat (STR) marker analysis was performed for haplotype sharing. RESULTS: In 11 families,18 new SACS mutations were found (12.9% of total cohort). Five patients displayed onset ages in adulthood, a feature not known to be associated with ARSACS. The remaining index patients displayed a classic early onset phenotype. Initial phenotypic presentation was atypical in several patients, obscuring the clinical diagnosis. A founder mutation in SACS was identified in 3 Belgian families. In one isolated patient, an intragenic SACS deletion of exons 3-5 was detected. Partial SACS deletions were not previously described. CONCLUSIONS: In this study, we enlarge the ARSACS phenotype and the underlying genetic spectrum of SACS mutations. Patients with ARSACS are more common than previously known and risk underdiagnosis due to late onset age and unusual presentation.
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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 | 0.000 |
| 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".