In this study we evaluated single nucleotide polymorphisms (SNPs) in several selenoprotein coding genes for an association with breast cancer: glutathione peroxidase 1 (GPX1), glutathione peroxidase 2 (GPX2), glutathione peroxidase 3 (GPX3), glutathione peroxidase 4 (GPX4), SELS, SEP15, SEPN1, SEPP1, SEPW1, thioredoxin reductase 1 (TXNRD1), and thioredoxin reductase 2 (TXNRD2). The gene discussed is GPX4; the disease is breast cancer.