Common C677T Polymorphism of the Methylenetetrahydrofolate Reductase Gene and the Risk of Venous Thromboembolism: Meta-Analysis of 31 Studies
Bibliographic record
Abstract
BACKGROUND: Although the common 677 C --> T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene is implicated in the development of hyperhomocysteinemia, its correlation with venous thromboembolism (VTE) remains controversial. We conducted a meta-analysis of previously published studies to clarify the role of the MTHFR 677 TT homozygous genotype in association with VTE. METHODS AND RESULTS: Relevant articles were retrieved from a systematic search of Medline and Embase from 1990 to September 2001. Two independent reviewers abstracted data on the characteristics of the cases with VTE and controls without VTE. We pooled the rates of the MTHFR 677 TT genotype in both groups, as well as the odds ratio (OR) of VTE in the presence of the TT versus CC or CT genotypes. In 31 published studies, comprising 4,901 cases and 7,886 controls, the pooled prevalence of the MTHFR 677 TT genotype was slightly higher among cases (14.3%) than controls (11.7%), conferring a borderline degree of heightened risk [pooled OR (OR(p)) 1.2, 95% confidence interval (CI) 1.1-1.4]. After excluding cases with a classic thrombophilia factor, the pooled prevalence rates of the MTHFR 677 TT genotype among 11 studies were 17.7 and 12.3%, respectively (OR(p) 1.5, 95% CI 1.2-1.9). CONCLUSIONS: The classic MTHFR C677T gene polymorphism is weakly associated with an increased risk of VTE. It is unlikely that the purported relationship between hyperhomocysteinemia and VTE is mediated by this gene defect to a substantial degree, although other undiscovered gene polymorphisms may explain this association. Until more compelling data are made available, we do not recommend that testing for the MTHFR C677T polymorphism be routinely included as part of any clinical thrombophilia assessment.
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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 | 0.015 | 0.035 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.018 | 0.043 |
| Bibliometrics | 0.006 | 0.009 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 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".