In this study, we used biological material from HDGC patients to formally prove that the single nucleotide variant in CDH1 (c.1901C>T) they carry in their germline, earlier identified as the missense variant A634V (Figure 1), is indeed a bona fide splice-site variant (r.1900_1936del; p. Ala634ProfsTer7). This evidence concerns the gene CDH1 and CDH1-related diffuse gastric and lobular breast cancer syndrome.