Inactive X chromosome-specific reduction in placental DNA methylation
Bibliographic record
Abstract
Genome-wide levels of DNA methylation vary between tissues, and compared with other tissues, the placenta has been reported to demonstrate a global decrease in methylation as well as decreased methylation of X-linked promoters. Methylation is one of many features that differentiate the active and inactive X, and it is well established that CpG island promoters on the inactive X are hypermethylated. We now report a detailed analysis of methylation at different regions across the X in male and female placenta and blood. A significant (P < 0.001) placental hypomethylation of LINE1 elements was observed in both males and females. Relative to blood placental promoter hypomethylation was only observed for X-linked, not autosomal promoters, and was significant for females (P < 0.0001) not males (P = 0.9266). In blood, X-linked CpG island promoters were shown to have moderate female methylation (66% across 70 assays) and low (23%) methylation in males. A similar methylation pattern in blood was observed for approximately 20% of non-island promoters as well as 50% of the intergenic or intragenic CpG islands, the latter is likely due to the presence of unannotated promoters. Both intragenic and intergenic regions showed similarly high methylation levels in male and female blood (68 and 66%) while placental methylation of these regions was lower, particularly in females. Thus placental hypomethylation relative to blood is observed globally at repetitive elements as well as across the X. The decrease in X-linked placental methylation is consistently greater in females than males and implicates an inactive X specific loss of methylation in the placenta.
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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 | 0.000 |
| 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".