BRCA1 and breast cancer: Moreover, a horizontal histogram revealed the frequent mutant genes in BC, namely TP53 (89.7%), ATRX (7.2%), BRCA2 (6.4%), BRCA1 (6.1%) and EGFR (3.4%) (Supplementary Figure 3A), indicating the downregulation of ATRX in BC drug resistance could be attributed to mutation.