Hereditary diffuse gastric cancer (HDGC) is an inherited genetic syndrome most often caused by an inactivating mutation in the E-cadherin gene (CDH1) located on chromosome 16. Individuals who inherit an inactive copy of the CDH1 gene are at significantly elevated risk for developing stomach cancer. For this reason, individuals with these mutations will often elect to undergo prophylactic gastrectomy, or a complete removal of the stomach to prevent this cancer. Mutations in CDH1 are also associated with high risk of lobular breast cancers, and may be associated with a mildly elevated risk of colon cancer. The most common form of stomach cancer associated with CDH1 mutations is diffuse-type adenocarcinoma. An estimated 70% of males and 56% of females who inherit an inactivating CDH1 mutation will develop this form of cancer by age 80. Female patients are also estimated to have a 42% lifetime risk of developing lobular breast cancer. The median age of gastric cancer diagnosis in individuals with a CDH1 inactivating mutation is 38 years of age, but cases have been reported as young as 14 years of age.

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Wiki: Hereditary diffuse gastric cancer