CDH1 and gastric cancer: Although detailed pathogenesis mechanisms of GC remain elusive, environmental factors combined with specific genetic alterations in the vulnerable population play critical roles in GC tumorigenesis.10–12 Because EOGC patients expose to environmental toxins much lesser than older patients, hereditary factors may be of more importance in EOGC tumorigenesis.13 Indeed, ∼10% to 25% of EOGC patients have a positive family history,6,9,14,15 some of whom have hereditary GC syndromes, such as hereditary diffuse GC with 25% to 50% of cases harboring germline CDH1 gene mutations.