BRCA1 and breast neoplasm: The introduction of PTEN to BRCA1 mutation-prediction algorithms is supported by single-cell analyses of temporal somatic events in BRCA1 breast tumor tissue, which revealed that loss of PTEN is an early event in the development of BRCA1 basal-like tumors, whereas TP53 mutations occur first in most luminal BRCA1 tumors [12].