Germline analysis in the proband revealed the pathogenic variant c.2114delT p.(Leu705CysfsTer17) in the heterozygosity (VAF~0.5) CDH1 gene (transcript NM_004360.5), leading to the diagnosis of hereditary diffuse gastric cancer (HDGC) syndrome (ORPHA 26610) (Figure 2), while BRCA1/2 analysis did not reveal any variant. The gene discussed is CDH1; the disease is Familial gastric cancer.