Fig. 1

Identification of BRCA DMRs. a Principal component analysis of the BRCA cancer (red) and healthy (blue) samples and visualization of the samples discarded using a quadratic discriminant analysis (cross). b CpG and G + C content of BRCA DMRs. Density lines are represented in blue. Two categories, CpG-poor and CpG-rich, were defined according to a threshold following y = − 1.4(x − 0.38) + 0.51. c Distance of BRCA DMRs to their closest gene TSS. Two categories, proximal and distal, were defined according to a 2 kilobase (Kb) threshold. d Levels of methylation in hyper-methylated BRCA DMRs (red) or hypo-methylated DMRs (blue) in cancer versus healthy samples in the different categories. Only DMRs with at least 20% methylation change and a starting methylation mean in healthy samples above 50% for DMRs hypo-methylated in cancer and below 50% for hyper-methylated ones are shown. e Number of BRCA hyper- or hypo-methylated DMRs in the different categories. f Example of hyper- and hypo-methylated BRCA DMRs