Further inspection of the network models built by Polympact on breast cancer GWAS variants revealed a putative interaction between two variants that, when present on the same allele, synergistically modulate the transcript level of CASP8 gene, a key regulator of apoptotic response already shown to be downregulated in breast cancer (49,50) and involved in cancer initiation when deficiently expressed (51,52). Here, CASP8 is linked to breast cancer.