Germline pathogenic or likely pathogenic (P/LP) variants in the CDH1 gene, which encodes E-cadherin, lead to the Diffuse Gastric and Lobular Breast Cancer (DGLBC, formerly hereditary diffuse gastric cancer, HDGC [MIM: 137215]) syndrome with an autosomal dominant pattern of inheritance. The gene discussed is CDH1; the disease is CDH1-related diffuse gastric and lobular breast cancer syndrome.