BRCA1 and invasive ductal breast carcinoma: Absent or reduced BRCA1 expression in tumors without BRCA1 pathogenic variants appears to be linked to hypermethylation of the BRCA1 promoter region [18], a condition reported in 9.1–37% of sporadic BCs and associated with infiltrating ductal carcinoma type, high tumor grade (grade II-III), ER negativity, basal marker expression, younger age at diagnosis, and poor prognosis [18,19,20,21,22,23,24,25,26,27,28,29].