CDH1 and Hereditary breast cancer: In 2020, the International Gastric Cancer Linkage Consortium (IGCLC) additionally defined new clinical groups with specific recommendations: (1) the group of patients with a proven mutation in the CDH1 gene, but exclusive manifestation as lobular breast cancer, was defined as hereditary lobular breast cancer (HLBC); (2) the group, which clinically fulfills familial HDGC criteria, in the absence of a relevant mutation, was designated as HDGC-like.