Polymorphisms: GSTO1*A140D (C419A; rs4925), GSTA1*A. and GSTA1*B alleles.Main findings: - increased risk of estrogen receptor-positive breast cancer for postmenopausal women carrying homozygous GSTO1*A140D variant, as compared with homozygous wild-type;- no clear association between the GSTA1 polymorphism and breast cancer among postmenopausal women. The gene discussed is ESR1; the disease is breast cancer.