PTGDS and breast neoplasm: Based on our LRpath results, we identified additional circadian genes, DRD1 (FDR < 9.9×10-7), CASP1 (FDR < 0.002), PTGDS (FDR < 4.8×10-23), and PGLYRP1 (FDR < 8.5×10-7) as hypermethylated in breast tumor samples (significance levels based on probe-level LIMMA analysis, see Methods); these genes play a role in the regulation and disruption of circadian rhythm (Additional file2: Figure S9).