Analysis of 522 TCGA breast cancers (with mutation information on 17,243 genes) also provided supporting evidence for involvement of ERCC6 as it revealed similar frequency of mutations and similar ratio of high- to low-impact mutations in ERCC6 and ERCC8 compared to known breast cancer susceptibility genes such as BRCA1, BRCA2, CHEK2, and BLM. This evidence concerns the gene ERCC8 and breast cancer.