HCN1 and breast cancer: In addition, no associations with breast cancer risk were observed for the estrogen metabolic enzyme gene SNPs CYP19A1 (rs700519), HSD17B1 (rs605059), COMT (rs4680), or UGT2B7 (rs7439366) or the GWAS-selected SNPs ZNF365 (rs10822013), FGFR2 (rs2981579), RAD51B (rs3784099), TOX3 (rs3803662), MAP3K1 (rs889312), or HCN1 (rs981782).