We compared methylation signals at BRCA1 between the basal-like, Luminal A, Luminal B and HER2-enriched breast tumour subtypes and although not at a significant level, we observed a similar trend along the same 20 probes where increased methylation was observed specifically in basal-like breast tumours compared with other subtypes (Fig. 3b). Here, ERBB2 is linked to breast neoplasm.