Estimates of heritability of atrial fibrillation in the Standardbred racehorse
Bibliographic record
Abstract
BACKGROUND: The number of Standardbred racehorses admitted to the Ontario Veterinary College Teaching Hospital (Guelph, Canada) for treatment of atrial fibrillation (AF) has been on the rise since the early 1990s. A small number of sires have been contributing to a large proportion of cases, indicating there may be a genetic predisposition to the arrhythmia in this breed. OBJECTIVES: The objectives of this study were to determine the heritability of AF in Standardbred horses and whether heritability of the arrhythmia differs across gaits and/or sexes. STUDY DESIGN: Heritability study based on retrospective review of clinical records and publicly available pedigree and racing records. METHODS: Standardbred horses admitted to hospital for treatment of AF that were born between 1978 and 2007 comprised the affected case population (n = 204). Five randomly selected racing contemporaries for each case, assumed to not suffer from the arrhythmia, comprised the control population (n = 1017). Racing contemporaries were identified by examining the race records of affected horses within the 6 months prior to their admission, and randomly selecting sex- and gait-matched horses from these races. Heritability was estimated from the sampled horses as a whole (n = 1221), as well as for both sexes and gaits, using a generalised linear mixed model. RESULTS: Heritability of AF on the underlying liability scale was estimated to be (±s.e.) 0.30±0.04 in the entire data set; 0.30±0.06 in males; 0.24±0.08 in females; and 0.32±0.05 in pacers. After conversion to the observed scale, heritability estimates were 0.14, 0.15, 0.09 and 0.15, respectively. MAIN LIMITATIONS: There were insufficient data to estimate heritability of AF for trotters. CONCLUSIONS: Modest heritability estimates were found for AF in the Standardbred horse, particularly in males and pacers, which support the hypothesis that there is a genetic contribution to the arrhythmia in this breed. The Summary is available in Chinese - See Supporting Information.
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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 | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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".