The International Gastric Cancer Linkage Consortium (IGCLC) defined the clinical criteria to select patients eligible for CDH1 germline mutations: (1) two or more documented cases of gastric cancer in first- or second-degree relatives regardless of age, with at least one confirmed diffuse gastric cancer; (2) diffuse gastric cancer before age 40 years without a family history; or (3) families with diagnoses of both diffuse gastric cancer and lobular breast carcinoma, at least one before age 50 years (van der Post et al., 2015b). This evidence concerns the gene CDH1 and breast lobular carcinoma.