The definition of the HDGC syndrome was established in 1999 by the IGCLC that also delineated the criteria for the CDH1 genetic screening, as follows: 1) two or more documented cases of diffuse gastric cancer in 1st/2nd degree relatives, with at least one diagnosed before the age of 50, or 2) three or more cases of documented diffuse gastric cancer in 1st/2nd degree relatives, independently of age of onset [2]. The gene discussed is CDH1; the disease is Familial gastric cancer.