Our current NHS2 findings, as well as those from the prior CTS study, now strongly suggest that the degree of breast cancer protection from preeclampsia depends on a mechanistic interaction between two population exposures: preeclampsia and inheritance of the functionally blunted IGF1R T allele of rs2016347 that causes a significant reduction in IGF1R mRNA expression observable in multiple normal organ and host tissues [38]. Here, IGF1R is linked to breast cancer.