These guidelines provide a framework for HLBC screening among CDH1 P/LP mutation carriers, but evidence in support of these recommendations borrows from similar guidelines for BRCA mutation carriers, who are more prevalent than CDH1 mutation carriers (0.2% vs. 0.06% of the general population) and more frequently develop invasive ductal carcinoma (IDC) rather than ILC8,14,15. Here, CDH1 is linked to invasive ductal breast carcinoma.