Fig. 1

Differentially methylated positions (DMPs) with sex in skeletal muscle. a Volcano plot of DNA methylation differences between males compared to females. Each point represents a tested CpG (633,645 in total) and those that appear in colour are DMPs at a meta-analysis false discovery rate < 0.005; red DMPs are hypermethylated in males compared with females; blue DMPs are hypomethylated in males compared with females. The x-axis represents the amount of DNA methylation difference between the sexes, and the y-axis represents statistical significance (higher = more significant). Two DMPs that were present in all three studies and showed the largest effect size are labelled with the respective CpG and boxplots of β-values from each study appear to the right (hyper-DMP) and left (hypo-DMP). b Principal component analysis plots of the methylation values at the DMPs; each point on the graph represents an individual; males denoted in green, females denoted in orange