Hereditary diffuse gastric cancer ( is an autosomal dominant cancer predisposition syndrome. Heterozygous CDH1 mutation carriers have a 70 to 80% lifetime risk of developing diffuse gastric cancer. In addition to gastric cancer, up to 60% of female mutation carriers develop lobular carcinoma of the breast, and some carriers may develop colorectal cancer. Identification of mutation carriers is important, because the characteristic microscopic foci of signet ring cell adenocarcinoma in HDGC usually involves the submucosa and is often not readily detectable by routine upper endoscopy screening (summary by Fitzgerald et al., 2010).

HDGC is considered to be a distinct disease entity from the more common sporadic occurrence of gastric cancer (613659), which can be associated with environmental factors, such as Helicobacter pylori infection, high-fat diet, or smoking, and is often associated with somatic mutations in disease tissue.