GPX6 and breast cancer: Six SNPs (rs406113 and rs974334 on the glutathione peroxidase 6 (GPX6) gene, rs1052133 on the 8-oxoguanine DNA glycosylase (OGG1) gene, rs2284659 on the superoxide dismutase 3 (SOD3) gene, rs4135225 on the thioredoxin (TXN) gene and rs207454 on the xanthine dehydrogenase (XDH) gene) are associated with variations in the predisposition to BC.