NATURAL SELECTION AT THE MJD LOCUS: PHENOTYPIC DIVERSITY, SURVIVAL AND FERTILITY AMONG MACHADO-JOSEPH DISEASE PATIENTS FROM THE AZORES
Bibliographic record
Abstract
Machado-Joseph Disease (MJD) is an autosomal dominant neurodegenerative disorder of adult onset, associated with the expansion of a (CAG)n tract in the coding region of the causative gene, localized on 14q32.1. Machado-Joseph Disease shows non-Mendelian features typical of other triplet repeat disorders, including clinical heterogeneity, variable age at onset and anticipation. Three phenotypes have been proposed (clinical types 1, 2 and 3). Type 1 is associated with early age at onset and a high repeat number of the CAG sequence, and Types 2 and 3 have later onset and lower numbers of CAG repeats. This paper investigates whether there is selection against the MJD gene, acting through differential survival. nuptiality and fertility associated with clinical type and age at onset. The study sample comprised 40 MJD patients from the Azores (Portugal) having fully documented reproductive histories and known dates of death. The proportion of married patients of each clinical type increased from 0.22 among Type 1 patients, to 0.40 in Type 2 and 0.95 in Type 3. Age at onset and length of survival were also associated with marital status, with the married cases having later mean age at onset and longer mean survival time. In the whole sample, clinical type was associated with fertility, with significantly fewer children born to Type 1 patients. Among married patients clinical type was not associated with age at marriage, reproductive span or number of children. No reduction of fertility was detected among married patients in whom the onset of MJD was below the age of 50. The authors' interpretation of these results is that the high-repeat CAG haplotypes associated with early age at onset and clinical Type 1 are selected against through reduced survival and fertility. The fertility component of selection is mediated by nuptiality rather than marital fertility.
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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 | 0.000 |
| 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) | 0.001 | 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".