CHEK2 and breast cancer: Several noteworthy genes that specifically were associated with ER + BC include FGFR2 and CHEK2. Several noteworthy genes that were associated with ER- BC include TP53 and its regulator MDM4. Interestingly, we discovered that TERT in the 5p15.33 locus was associated with both ER- and ER + BC in our TWAS, while TERT was previously believed to be a predominantly ER- locus in GWAS.