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Introduction: The objective of this study was to reclassify published germline CDH1 variants identified in gastric cancer (GC) in accordance with the latest ClinVar definition and to correlate their pathogenicity with the established international clinical criteria for genetic testing. Methods: The relevant literature dating from 1998 to 2019 was systematically searched for data on CDH1 germline mutations in accord with PRISMA guidelines. The collected variants were classified according to the latest ClinVar definition into the following classes: benign (B), likely benign (LB), pathogenic (P), likely pathogenic (LP), and variant of unknown significance (VUS). The McNemar test was used to compare the adequacy of current versus previous International GC Linkage Consortium (IGCLC) criteria. Results: We reclassified a total of 247 CDH1 variants, and we identified that about 70% of B/LB variant carriers were not fulfilling the defined clinical criteria. Instead, all P/LP variants (100%) were associated with the hereditary diffuse gastric cancer (HDGC) phenotype fulfilling the 2020 ILGCC criteria, with a significant improvement (p = 0.025) compared to previous version. Conclusions: We conclude that germline CDH1 genetic testing is indicated only in families meeting the clinical criteria for the HDGC syndrome. This observation suggests that clinical phenotypes that do not clearly fulfill these criteria should not be considered for CDH1 genetic testing. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to determine the male and female frequency of diffuse gastric cancer (DGC), the age at diagnosis, and the country of origin in a selected population with germline CDH1 variants from families with the hereditary diffuse gastric cancer (HDGC) syndrome. Methods: Relevant literature dating from 1998 to 2021 was systematically searched for data on CDH1 gene. The Wilcoxon rank sum test and the Chi-square test were used to estimate if the difference observed between patients with gastric cancer (GC) and unaffected individuals was significant. Results: We identified 80 families fulfilling the established clinical criteria for HDGC CDH1 genetic screening. There were more women than men with DGC and germline CDH1 variant (65.5%). Stratifying the age at diagnosis, we identified an association between DGC, positive CDH1 screening and young women (≤ 40 years) (p = 0.015). The mean age at diagnosis was 39.6 ys for women and 42.5 ys for men. There was an association between CDH1 carrier status and DGC (p = 0.021). Conclusions: Young women carrying germline CDH1 variants with DGC are comparatively frequent in the HDGC syndrome, and potentially at higher risk to develop DGC particularly in low-incidence areas for GC. [ABSTRACT FROM AUTHOR]

Abstract: Aim: CDH1 germline alterations occur in about 40% of hereditary diffuse gastric cancer (HDGC) families. CDH1 germline mutations are also documented in few early onset diffuse gastric cancer patients (EODGC) without family history, but the real frequency in this setting in unknown. In these patients, the advanced stage at the time of diagnosis remains a clinical burden due to the poor long term survival. Methods: The entire coding region and exon flanking sequences of the CDH1 gene was analysed by direct sequencing in 21 EODGC patients aged ⩽50years. The potential deleterious nature for a new CDH1 missense variant was assessed by cell–cell aggregation and invasion assays. Somatic CDH1 mutation, loss of heterozigosity (LOH) and promoter hypermethylation was explored in the tumour from one CDH1 germline mutation carrier. Results: Two novel CDH1 germline variants were identified in 21 EODGC cases, c.670C>T and –63C>A. Functional analysis of the c.670C>T missense variant classified this mutation as non-pathogenic. The analysis of CDH1 somatic second hits failed to demonstrate E-cadherin structural and epigenetic alterations in the tumour sample. Conclusion: Data from the present work and a systematic review of the literature revealed that CDH1 germline mutations occurred in 7.2% of EOGC patients invariably with diffuse of mixed histology. From these, proved CDH1 mutation pathogenicity has been assigned only to 2.3% of the cases who were recurrently diagnosed before 35years old. Germline CDH1 mutation remain the only germline genetic defect described in this type of patients and CDH1 mutation screening should be recommended for patients with these characteristics. [Copyright &y& Elsevier]

Abstract: Aim: Mitogen-activated protein kinase (MAPK) cascade and phosphatidylinositol 3-kinase (PI3K) survival pathways are frequently activated in the progression of gastrointestinal malignancies. In this study, we aimed to determine the frequency of gene mutations in members of these pathways – Epithelial Growth Factor Receptor (EGFR), KRAS, BRAF, PIK3CA and MLK3 in a series of 63 gastric carcinomas with high levels of microsatellite instability (MSI). Methods: Gene mutation analysis was performed by PCR amplification followed by direct sequencing. In selected tumour cases, EGFR expression was evaluated by immunohistochemistry. Association studies between molecular data and clinicopathologic characteristics were performed. Results: Mutations in EGFR (3′-untranslated region [UTR] polyA repeat), KRAS, PIK3CA and MLK3 genes occurred in 30 (47.6%), 11 (17.5%), 9 (14.3%) and 2 (3.2%) of the MSI gastric cancer (GC) cases, respectively. No BRAF or EGFR hotspot mutations were identified. Overall, mutations in at least one of these genes were found in 55.6% (35/63) of gastric carcinomas. From those mutant cases 40.0% (14/35) of them had concomitant gene mutations, always involving EGFR polyA deletions. Interestingly, we observed significant associations between oncogenic mutations and female gender (p =0.046) old age of diagnosis (p =0.001) and intestinal subtype (p =0.043). Conclusion: Our results show that MSI gastric carcinoma frequently shows activation of EGFR-MAPK and PI3K pathways. Within all alterations found, deletions of the A13 repeats of EGFR were common, suggesting this molecular event as an important biomarker for stratification of GC patients for treatment with EGFR inhibitors. [Copyright &y& Elsevier]

Simple Summary: E-cadherin (CDH1 gene) germline mutations are associated with the development of the autosomal cancer syndrome known as hereditary diffuse gastric cancer. About 30% of families fulfilling the clinical criteria established by the International Gastric Cancer Linkage Consortium have constitutional alterations of the CDH1 gene. Different patterns of CDH1 germline mutations have described as truncating, deletion, insertion, splice site, non sense, silence, and at last, missense alterations. The frequency of the different E-cadherin germline mutations in countries with different incidence rates for gastric carcinoma has reported extremely variable. In this study we aimed to assess the worldwide frequency of CDH1 germline mutations in gastric cancers coming from different geographical areas, using a systematic approach. Hereditary diffuse gastric cancer (HDGC) is a complex and multifactorial inherited cancer predisposition syndrome caused by CDH1 germline mutations. Nevertheless, current CDH1 genetic screening recommendations disregard an unbalanced worldwide distribution of CDH1 variants, impacting testing efficacy and patient management. In this systematic review, we collected and analyzed all studies describing CDH1 variants in gastric cancer patients originating from both high- and low-prevalence countries. Selected studies were categorized as family study, series study, and unknown study, according to the implementation of HDGC clinical criteria for genetic testing. Our results indicate that CDH1 mutations are more frequently identified in gastric cancer low-incidence countries, and in the family study group that encompasses cases fulfilling criteria. Considering the type of CDH1 alterations, we verified that the relative frequency of mutation types varies within study groups and geographical areas. In the series study, the missense variant frequency is higher in high-incidence areas of gastric cancer, when compared with non-missense mutations. However, application of variant scoring for putative relevance led to a strong reduction of CDH1 variants conferring increased risk of gastric cancer. Herein, we demonstrate that criteria for CDH1 genetic screening are critical for identification of individuals carrying mutations with clinical significance. Further, we propose that future guidelines for testing should consider GC incidence across geographical regions for improved surveillance programs and early diagnosis of disease. [ABSTRACT FROM AUTHOR]

Simple Summary: Diffuse gastric cancer is the hallmark of the hereditary diffuse gastric cancer syndrome related with the E-cadherin germline mutations. Other cancers (non-gastric) are described in association with the CDH1 gene germline alterations. In this study, we aimed to assess the overall frequency of CDH1 mutations in non-gastric tumors reported in literature so far. Hereditary Diffuse Gastric Cancer (HDGC) is a complex inherited syndrome caused by CDH1 germline mutations. DGC is the hallmark cancer of this genetic predisposition, but several other cancers are associated with these CDH1 mutations. In this review, we revised all studies reporting CDH1 mutations in non-GC patients. The selected studies included: (a) families aggregating with GC and other cancers, both, and (b) families presenting only non-gastric tumors association. Among non-gastric tumors, our results show that CDH1 mutations are most frequently identified in breast cancer. The frequency of missense mutations is higher in the non-GC group, as the age at diagnosis in this group. Moreover, the predominant CDH1 mutation affects the extracellular domain. Our data suggest that CDH1 genetic testing should be considered also in other cancers, especially breast tumors. [ABSTRACT FROM AUTHOR]