Fig. 2

Age-related DNA methylation sites in normal-adjacent breast tissue gain methylation in breast cancer. a–d Volcano plots of age-related hypermethylated (a), age-related hypomethylated (b), not age-related (c), and unmethylated sites (d) in TCGA breast tumors compared to normal samples. The x-axis is the methylation difference between the average methylation (β values) for 784 breast tumors and 97 normal-adjacent samples; the sites with a methylation difference between tumor and normal of at least 20% are indicated in red (hypermethylation) or in blue (hypomethylation). The y-axis is the –log10 of q value. Cutoff at the y-axis is at –log10 (q value) = 3. e Summary of odds ratios: the upper panel is for hypermethylation in unmethylated, not-age, and age sites compared to hypermethylated sites in all the datasets, and the lower panel is for hypomethylation with comparisons done in the same categories. The numbers on top of the dots represent the estimates of the odds ratio, and the error bars represent the 95% confidence intervals around the estimates. All comparisons were tested for significance by a chi-square test (p value < 0.0001)