PIWIL1 and breast cancer: Here, we selected 41 SNPs in 14 candidate genes (AGO1, AGO2, DICER1, DGCR8, DROSHA, FMR1, GEMIN3, GEMIN4, HIWI, RAN, TARBP2, XPO5, p68 and p72) involved in the canonical miRNA biogenesis pathway [19,20] and evaluated the associations with breast cancer survival.