Recently, in unselected breast cancer patients, several genome-wide association studies (GWAS) or studies of specific candidate single nucleotide polymorphisms (SNPs) have revealed a number of novel genetic susceptibility variants and loci, including FGFR2, TOX3/LOC643714, LSP1, MAP3K1, chromosome 8q24, and CASP8, which were independently associated with an increased risk of breast cancer. The gene discussed is MAP3K1; the disease is breast cancer.