BRCA1 and breast cancer: In a subsequent validation analysis using 15,252 BRCA1 and 8,211 BRCA2 mutation positive individuals to assess disease subtype-specific associations for 74 previously identified breast cancer susceptibility loci, several chromosomal regions discussed above, including 5p15.33 (TERT), 6q25.1 (ESR1), and 19p13.11, showed a significant association with increased risk of TNBC in BRCA1 mutation positive individuals [20].