BRCA1 and in situ carcinoma: Only occasionally, a differentiation between BRCA1 and BRCA2 carriers is made with a trend to start later or decrease mammography frequency in BRCA1 compared to BRCA2 carriers, probably based on the possible higher likelihood of microcalcifications as a reflection of in situ carcinoma in ER-positive breast cancers which are enriched in BRCA2 [42, 45].