ESR1 and breast cancer: But no association between a polymorphism in genes CYP17 (5′untranslated MspA1 polymorphism), CYP19 (generated by a G → T substitution in intron 6), involved in the sex hormone biosynthesis pathway, and Pvull (lipoprotein lipase) polymorphism (generated by a C → T substitution in intron 1) in the estrogen receptor ESR1 gene and the risk of breast cancer was demonstrated (Chen et al., 2008).