The E‐cadherin (E‐cad) gene (CDH1) [OMIM + 192090] is a calcium‐dependent cell‐to‐cell adhesion molecule and tumour suppressor protein that is the only germline molecular defect associated with hereditary diffuse gastric and lobular breast cancers.1, 2 The E‐cad protein plays a critical role in establishing and maintaining polarized and differentiated epithelia through intercellular adhesion complexes. This evidence concerns the gene CDH1 and breast cancer.