RUNX1T1 and breast cancer: TP53‐mut BCs were detected with significantly more mutations in ERBB2 (p < 0.001), CDK12 (p < 0.001), NBN (p = 0.009) and PREX2 (p = 0.024) than the wild‐type, while MYC‐amp BC had significantly higher mutation rates in NBN (p < 0.001), PTK2 (p = 0.015), RUNX1T1 (p = 0.002), PRKDC (p < 0.001) and PREX2 (p = 0.016).