Targeted multigene panel sequencing enables testing of genes known to be associated with familial breast cancer in addition to other known hereditary cancer syndromes, of which breast cancer is a component, namely, TP53 (early onset breast cancer), CDH1 (invasive lobular, hereditary diffuse gastric cancer syndrome) and PTEN (Cowden syndrome) [5–7]. This evidence concerns the gene CDH1 and breast cancer.