Clinical and Genetic Profile of Brazilian Patients with Late-Onset Friedreich’s Ataxia (P2.031)
Bibliographic record
Abstract
OBJECTIVE: To evaluate the clinical and genetic characteristics of late-onset Friedreich ataxia (LOFA) in a Brazilian series. BACKGROUND:Friedreich’s ataxia (FDRA) is the most common inherited ataxia worldwide.Patients usually have early onset ataxia, arreflexia with Bisbisnski’s sign,scoliosis and pes cavus, but at least 25% of cases have atypical phenotypes. Disease begins after the age of 25 in occasional patients (late-onset Friedreich’s ataxia-LOFA). Little is known about the frequency and clinical profile of LOFA-patients. DESIGN/METHODS:Sixty two consecutive patients with molecular confirmation of FDRA and followed in 2 outpatient Brazilian centers were enrolled. General demographics,GAA expansion, age at onset, clinical characteristics were evaluated and compared among the LOFA and classic FDRA (cFDRA) groups. We used Mann-Whitney and Fisher tests to compare means and proportions between groups, p values <0.05 were considered significant. RESULTS:There were 9/62 (14.5%) LOFA and 53/62 (85.5%) cFDRA patients. There were 3 men in LOFA group and 27 in cFDRA. Mean age and age at onset of cFDRA and LOFA groups were 23.5±7.9 vs. 55.3±11.51 years (p<0.001), and 11.1±5.58 vs. 36±7.46 years (p<0.001), respectively. LOFA group had shorter GAA-expansions (GAA1: 328.6±180 vs. 492.8±263.7 p<0.001; GAA2: 761.8 ±198.8 vs.923.5±83.1, p<0.001).One of the LOFA families presented a pseudo-dominant inheritance pattern. Spasticity and sustained reflexes were found in 4/9 (44.4%) patients with LOFA but in none of cFRDA-patients. Skeletal deformities were less frequent in LOFA group (pes cavus 11.1% vs. 79.2% p<0.001, and scoliosis 22.2% vs 56.6% p=0.07). Cardiomyopathy (11.1% vs.32%) and diabetes/impaired glucose tolerance (0% vs.17%) were slightly more frequent in the cFRDA group but differences did not reach statistical significance (p=0.263 and 0.333 respectively). CONCLUSIONS:LOFA accounts for 14.5% of Brazilian FRDA patients. Remarkable pyramidal signs and rare skeletal deformities could distinguish LOFA from cFRDA. This unusual phenotype often makes LOFA diagnosis challenging, so that clinicians should be aware of this FRDA variant. Study Supported by:
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.002 | 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".