Figure 2.

Volcano plots show the directions of associations in epigenome-wide meta-analyses of circulating vitamin B12 concentrations during foetal development.

Abbreviations: B12, vitamin B12; CpG, cytosine-phosphate-guanine site; FDR, false discovery rate; SDS, standard deviation score.

Upper panel: maternal meta-analysis;Lower panel: newborn meta-analysis

The X-axis represents the difference in DNA methylation per SDS increase in circulating vitamin B12 concentrations; the Y-axis represents the −log₁₀(P). The red dotted line and the blue line represent the thresholds below which we considered associations significant using a Bonferroni correction (absolute P-value <1.2 × 10⁻⁷) and FDR-P-value <0.05, respectively, to account for multiple testing. In total, 56.1% of all analysed CpGs in the maternal meta-analysis showed increased methylation in relation to maternal vitamin B12 concentrations during pregnancy. Similarly, 51.4% of all analysed CpGs in the newborn meta-analysis showed increased methylation in relation to higher newborn circulating vitamin B12 concentrations.