In sporadic LBC (germline CDH1 VUS or LB), discordances between germline and tumor testing were observed in 2 of 7 cases (28.6%), including 1 germline intronic CDH1 variant (c.2295+16C>A) and 1 germline CDH1 copy number variant ([?_68768071]_[68869950_?]dup) missed by tumor sequencing. The gene discussed is CDH1; the disease is CDH1-related diffuse gastric and lobular breast cancer syndrome.