ESR2 and breast cancer: The rs4986938 and rs1256049 are the most extensively studied variants of the ESR2 gene (Yu et al., 2011; Haldosén, Zhao & Dahlman-Wright, 2014), but they have demonstrated contradictory results; some have been associated with susceptibility development to BC (Dai et al., 2014), whereas others have not (Wang et al., 2013; Ghali et al., 2018).