The observed hypomethylation in the far upstream region of BRCA1 (green squares for BRCA1_1 in Figure 1A) was found mainly in estrogen receptor negative tumours like the basal-like tumours further supporting the hypothesis that the genome-wide hypomethylation observed in breast cancer (as well as in any other cancer types) might be more pronounced in this tumour subclass. This evidence concerns the gene BRCA1 and breast cancer.