Early-onset Diffuse Gastric Cancer Research Articles

A Systematic Review on Clinical and Health-Related Quality of Life Outcomes following Total Gastrectomy in Patients with Hereditary Diffuse Gastric Cancer

Hereditary diffuse gastric cancer (HDGC) is an autosomal-dominant syndrome associated with early onset diffuse gastric cancer. Definitive treatment is prophylactic total gastrectomy (PTG) associated with significant morbidity. Studies published from January 2000 to December 2022 reporting clinical, histopathological or health-related quality of life outcomes in HDGC patients undergoing PTG were identified. The study quality was assessed by the “Newcastle–Ottawa scale”. Of the 257 articles screened, 21 were selected. A total of 353 patients were examined in 15 studies that reported surgical outcomes. The median age was 42 years old. The median major complication and mortality rates were 19.2% and 0.3%, respectively. The most common complications were wound infection at 4.8% followed by anastomotic leak and pulmonary complications at 4.5% each. Following PTG, 88.6% of patients had early lesions amongst 414 patients. The mean/median number of signet ring cell carcinoma foci in the gastrectomy specimens was from 2 to 78. All cases were stage 1 with no lymph node involvement. There was a wide range of psychosocial effects following PTG closely related to the physical symptoms. It is imperative for patients to receive comprehensive preoperative counselling to make an informed decision and be followed up under the care of a multidisciplinary team.

Combined loss of CDH1 and downstream regulatory sequences drive early-onset diffuse gastric cancer and increase penetrance of hereditary diffuse gastric cancer

BackgroundGermline CDH1 pathogenic or likely pathogenic variants cause hereditary diffuse gastric cancer (HDGC). Once a genetic cause is identified, stomachs’ and breasts’ surveillance and/or prophylactic surgery is offered to asymptomatic CDH1 carriers, which is life-saving. Herein, we characterized an inherited mechanism responsible for extremely early-onset gastric cancer and atypical HDGC high penetrance.MethodsWhole-exome sequencing (WES) re-analysis was performed in an unsolved HDGC family. Accessible chromatin and CDH1 promoter interactors were evaluated in normal stomach by ATAC-seq and 4C-seq, and functional analysis was performed using CRISPR-Cas9, RNA-seq and pathway analysis.ResultsWe identified a germline heterozygous 23 Kb CDH1-TANGO6 deletion in a family with eight diffuse gastric cancers, six before age 30. Atypical HDGC high penetrance and young cancer-onset argued towards a role for the deleted region downstream of CDH1, which we proved to present accessible chromatin, and CDH1 promoter interactors in normal stomach. CRISPR-Cas9 edited cells mimicking the CDH1-TANGO6 deletion display the strongest CDH1 mRNA downregulation, more impacted adhesion-associated, type-I interferon immune-associated and oncogenic signalling pathways, compared to wild-type or CDH1-deleted cells. This finding solved an 18-year family odyssey and engaged carrier family members in a cancer prevention pathway of care.ConclusionIn this work, we demonstrated that regulatory elements lying down-stream of CDH1 are part of a chromatin network that control CDH1 expression and influence cell transcriptome and associated signalling pathways, likely explaining high disease penetrance and very young cancer-onset. This study highlights the importance of incorporating scientific–technological updates and clinical guidelines in routine diagnosis, given their impact in timely genetic diagnosis and disease prevention.Graphical abstract

CDH1 germline mutations in a Chinese cohort with hereditary diffuse gastric cancer

Germline mutations in CDH1 are associated with hereditary diffuse gastric cancer (HDGC) and have been identified in multiple ethnicities. However, CDH1 germline mutations have seldom been documented in Chinese patients with HDGC, and their frequency remains unclear. Here, we aimed to examine the frequency of CDH1 germline mutations in Chinese patients with HDGC. In total, 285 patients who met the International Gastric Cancer Linkage Consortium 2015 testing criteria of HDGC for CDH1 germline mutations were recruited. All 16 CDH1 exons, including neighboring intronic sequences, were amplified using polymerase chain reaction and screened using Sanger sequencing. Variants were analyzed using Mutation Surveyor V4.0, SIFT, and PolyPhen-2 software. Three nonsense and nine missense CDH1 germline mutations were identified in 21 of 285 index cases (7.4%). Two CDH1 germline mutations, N405Y (Asn405Tyr) and W409X (Trp409Ter), were identified as new variants. In addition, up to 28.6% of CDH1 mutations in the 21 indicated patients were identified as c.1775G>C (E551Q). The frequency of CDH1 mutations was 6.5% (7/108) in HDGC and 7.9% (14/177) in early onset diffuse gastric cancer (EODGC). The mutation detection rates of CDH1 in males and females were 6.7% (4/60) and 8.5% (10/117) in EODGC and 4.6% (3/65) and 9.3% (4/43) in HDGC, respectively. These data reveal, for the first time, the type and frequency of CDH1 germline mutations in Chinese HDGC and demonstrate that germline CDH1 mutations are a noteworthy contributor to the high frequency of HDGC in Chinese.

The CDH1 c.1901C>T Variant: A Founder Variant in the Portuguese Population with Severe Impact in mRNA Splicing.

Simple SummaryAn unexpectedly high number of early-onset diffuse gastric and lobular breast cancer in apparently unrelated families carrying the same CDH1 c.1901C>T variant (formerly known as missense p.A634V) in Northern Portugal suggested a founder effect in this region. We demonstrated that c.1901C>T is a truncating variant triggered by cryptic splicing, calculated its mutational age, and characterized the tumour spectrum and age of onset in affected families.Hereditary diffuse gastric cancer (HDGC) caused by CDH1 variants predisposes to early-onset diffuse gastric (DGC) and lobular breast cancer (LBC). In Northern Portugal, the unusually high number of HDGC cases in unrelated families carrying the c.1901C>T variant (formerly known as p.A634V) suggested this as a CDH1-founder variant. We aimed to demonstrate that c.1901C>T is a bona fide truncating variant inducing cryptic splicing, to calculate the timing of a potential founder effect, and to characterize tumour spectrum and age of onset in carrying families. The impact in splicing was proven by using carriers’ RNA for PCR-cloning sequencing and allelic expression imbalance analysis with SNaPshot. Carriers and noncarriers were haplotyped for 12 polymorphic markers, and the decay of haplotype sharing (DHS) method was used to estimate the time to the most common ancestor of c.1901C>T. Clinical information from 58 carriers was collected and analysed. We validated the cryptic splice site within CDH1-exon 12, which was preferred over the canonical one in 100% of sequenced clones. Cryptic splicing induced an out-of-frame 37bp deletion in exon 12, premature truncation (p.Ala634ProfsTer7), and consequently RNA mediated decay. The haplotypes carrying the c.1901C>T variant were found to share a common ancestral estimated at 490 years (95% Confidence Interval 445–10,900). Among 58 carriers (27 males (M)–31 females (F); 13–83 years), DGC occurred in 11 (18.9%; 4M–7F; average age 33 ± 12) and LBC in 6 females (19.4%; average age 50 ± 8). Herein, we demonstrated that the c.1901C>T variant is a loss-of-function splice-site variant that underlies the first CDH1-founder effect in Portugal. Knowledge on this founder effect will drive genetic testing of this specific variant in HDGC families in this geographical region and allow intrafamilial penetrance analysis and better estimation of variant-associated tumour risks, disease age of onset, and spectrum.

Cancer predisposition and germline CTNNA1 variants

Hereditary Diffuse Gastric Cancer (HDGC) is a cancer predisposing syndrome mainly caused by germline inactivating variants in CDH1, encoding E-cadherin. Early-onset diffuse gastric cancer (DGC) and/or invasive lobular breast cancer (LBC) are the main phenotypes in CDH1-associated HDGC. CTNNA1, encoding for α-E-catenin, and E-cadherin-partner in the adherens junction complex, has been recently classified as a HDGC predisposing gene. Nevertheless, little is known about CTNNA1 tumor spectrum in variant carriers and variant-type associated causality. Herein, we systematically reviewed the literature searching for CTNNA1 germline variants carriers, further categorized them according to HDGC clinical criteria (HDGC vs non-HDGC), collected phenotypes, classified variants molecularly and according to CDH1 ACMG/AMP guidelines and performed genotype-phenotype analysis. We found 41 families carrying CTNNA1 germline variants encompassing in total 105 probands and relatives. All probands from 13 HDGC families presented DGC and their average age of onset was 40 ± 17 years; 10/13 (77%) HDGC families carried a pathogenic (P) variant. Most probands from 28 non-HDGC families developed unspecified-BC, as well as most of their relatives; 4/28 (14%) carried a P variant, 16/28 (57%) carried a likely pathogenic (LP) variant, 7/28 (25%) carried variants of unknown significance (VUS) and 1/28 (4%) carried a likely benign variant. Regardless of clinical criteria, 97% (32/33) of probands and relatives from P variant-carrier families had DGC/unspecified-GC. In LP variant-carrier families, 82% (28/34) of probands and relatives had unspecified-BC. Only 2/105 individuals had LBC. A cluster of frameshift and nonsense variants was found in CTNNA1 last exon of non-HDGC families and classified as VUS. In conclusion, current available data confirms an association of CTNNA1 P variants with early-onset DGC, but not with LBC. We demonstrate that in ascertained cohorts, CTNNA1 P variants explain <2% of HDGC families and support the use of ACMG/AMP CDH1 specific variant curation guidelines, while no specific guidelines are developed for CTNNA1 variant classification. Moreover, we demonstrated that truncating variants at the CTNNA1 NMD-incompetent last exon have limited deleteriousness, and that CTNNA1 LP variants have lower actionability than CDH1 LP variants. Current knowledge supports considering only CTNNA1 P variants as clinically actionable in HDGC carrying families.

Predicting Pathogenicity of CDH1 Gene Variants in Patients with Early-onset Diffuse Gastric Cancer from Western Mexico.

Early-onset diffuse gastric cancer (EODGC) occurs at or before 50 years of age. Pathogenic mutations and germline deletions in the CDH1 gene (E-cadherin) are well-documented genetic factors associated with the causes of EODGC. The objective of the study was to study CDH1 germline variants and their potential functional impact in patients with EODGC in a Mexican population. We studied seven EODGC patients from a biomedical research center in western Mexico. Variants were identified by Sanger sequencing and multiplex ligation-dependent probe amplification. The DeepSEA and SNPClinic v.1.0 software and the Ensembl (1000 Genomes Project, 1kGP) and ClinVar databases were used to predict functional single-nucleotide polymorphisms (SNPs). The genetic admixture of the Mexican patients was corroborated by 22 short tandem repeat loci genotyping and structure analysis. We found 12 germline CDH1 variants in all EODGC patients, and all of them are considered as polymorphisms: rs34561447, rs5030625, rs16260, rs1330727101, rs28372783, rs942269593, rs3743674, rs1801552, rs34939176, rs33964119, rs3556654, and rs1801026. The prediction of regulatory SNPs in the promoter suggests a role for a retrovirus in EODGC that induces the transcription of interferon-related genes through toll-like receptor-interferon response factor 3 signaling, as three SNPs in the CDH1 promoter alter three binding sites for this transcription factor. In addition, SNPs rs28372783 and rs1801026 could alter upstream stimulatory factors 1 (USF1)/USF2-mediated telomerase-dependent lymphocyte activation in EODGC. Other interesting result is a CTCF-dependent shorter CDH1 isoform lacking exon 14, probably due to exon-skipping mediated by rs33964119. Classical pathogenic germline mutations in the CDH1 gene were not found in these 7 EODGC patients. However, the in silico approaches revealed the possible involvement of a retrovirus and a shorter E-cadherin isoform in EODGC. Nevertheless, further in vitro and in vivo assays are needed to confirm these predictions.

A validated survival nomogram for early-onset diffuse gastric cancer.

This study aimed to establish and independently validate a prognostic nomogram for individual risk prediction in patients with early-onset diffuse gastric cancer (EODGC). Data for 794 patients with EODGC from the SEER database were randomly assigned to training (N=558) and internal validation (N=236) sets, and data for 82 patients from the Renmin Hospital of Wuhan University (RMHWHU) were used as an independent validation cohort. Our LASSO regression analyses of the training set yielded five clinicopathological features (race, AJCC stage, surgery for primary site, chemotherapy and tumor size), which were used to create a survival nomogram. Our survival nomogram achieved better predictive performance than the AJCC staging system, the current standard. Additionally, the calibration curves of the prognostic nomogram revealed good agreement between the predicted survival probabilities and the ground truth values. Indeed, our nomogram, which estimates individualized survival probabilities for patients with EODGC, shows good predictive accuracy and calibration ability for both the SEER and RMHWHU cohorts. These results suggest that a survival nomogram may be better at predicting OS for EODGC patients than the AJCC staging system.

Loss-of-function variants in CTNNA1 detected on multigene panel testing in individuals with gastric or breast cancer

PurposeCTNNA1 is a potential diffuse gastric cancer risk gene, however CTNNA1 testing on multigene panel testing (MGPT) remains unstudied. MethodsDe-identified data from 151,425 individuals who underwent CTNNA1 testing at a commercial laboratory between October 2015 and July 2019 were reviewed. Tissue α-E-catenin immunohistochemistry was performed on CTNNA1 c.1351C>T (p.Arg451*) carriers. ResultsFifty-two individuals (0.03% tested) had CTNNA1 loss-of-function (LOF) variants and 1057 individuals (0.7% tested) had a total of 302 distinct missense variants of uncertain significance. Detailed history was available on 33 CTNNA1 LOF carriers, with 21 unique CTNNA1 LOF variants. Four (12%) individuals had diffuse gastric cancer and 22 (67%) had breast cancer. Six (21%) and 24 (83%) of the 29 families reported a history of gastric or breast cancer, respectively. The CTNNA1 c.1351C>T nonsense variant was identified in three separate families with early-onset diffuse gastric cancer or breast cancer. Immunohistochemistry showed decreased α-E-catenin expression in gastric cancers. ConclusionCTNNA1 LOF variants are detected on MGPT with a majority of these individuals having gastric or breast cancer. The overall risk of gastric cancer for CTNNA1 LOF carriers may be lower than expected. Given the uncertain phenotype and penetrance, management of individuals with CTNNA1 LOF variants remains challenging.

808P - Investigation on gastric cancer susceptibility genes in Chinese early-onset diffuse gastric cancer

BackgroundHereditary diffuse gastric cancer (HDGC) is closely related to germline mutation of CDH1. In addition, potential pathogenic germline variants in other candidate genes were detected in FGC and HDGC families. However, comprehensive genetic profile of HDGC predisposing gene variants in Chinese Familial gastric cancer (FGC) and HDGC patients are yet to be elucidated. MethodsWe collected peripheral blood from 28 early-onset DGC patients and from a first degree relative DGC patient who was diagnosed at age of 50. All 29 patients fulfilled IGCLC 2015 criteria for HDGC clinical diagnosis and genetic testing. Genomic DNA was extracted from peripheral blood followed by Whole Exome Sequencing (WES) with average sequencing depth of at least 100X. Gastricancer predisposing SNV and Indel candidates were filtered based on population allele frequencies in public nucleotide polymorphism databases and corresponding functional impact was predicted by in silico tools. ResultsAmong previously reported gastric cancer susceptibility genes, CDH1, BRCA2, MAP3K6 expressed the most predisposing SNV and Indel candidates. In addition, a novel splice-site variant, c.2165-1G>A, in CDH1 was detected in a Chinese early-onset HDGC patient who developed ovarian metastasis. Moreover, BCR gene exhibited as the most prevalent gastric cancer predisposing gene with filtered variants primarily enriched in RhoGAP domain. Pathway enrichment analysis showed that the top three predisposing variant candidates were enriched in the following signalling pathway: ECM-receptor interaction (P-Value: 0.001), focal adhesion (P-Value: 0.02) and protein digestion and absorption (P-Value: 0.002). ConclusionsThis study suggested that CDH1, BRCA2, MAP3K6 may act as potential gastric cancer susceptibility genes in Chinese early-onset HDGC patients. Further study may be required to investigate the functional role of BCR abnormality, especially in its RhoGAP domain, in the tumorigenesis of gastric cancer. Moreover, to further investigate molecular mechanisms of early-onset gastric cancer, one may consider genes involved in three signalling pathways: ECM-receptor interaction, focal adhesion and protein digestion and absorption. Legal entity responsible for the studyPeking University Cancer Hospital. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

Hereditary diffuse gastric cancer: cancer risk and the personal cost of preventive surgery

Germline CDH1 mutation carriers are at risk for early-onset diffuse gastric cancer (DGC) and female carriers have an additional risk of lobular breast cancer. The reported literature GC risk of 70% has led to the recommendation for germline mutation carriers to undergo prophylactic total gastrectomy (PTG). The objective of this research was to examine post-surgical clinical outcomes and to identify which of the domains/symptoms from the European Organisation for Research and Treatment of Cancer QOL Questionnaire (EORTC QLQ-C30) were determinants of overall quality of life (QOL) in individuals undergoing PTG. Participants were recruited through multiple sources. Postsurgical clinical outcomes were obtained from hospital records. Participants completed validated questionnaires measuring generic and condition specific QOL (PROMIS, EORTC and SF 36v.II) at a single point in time. The mean QOL in this cohort was 70.6 (SD = 25.6), which is better than reference values from the general populations in USA and Canada Role and social function plus the symptoms anxiety, pain, taste, dyspnea and diarrhea were significant predictor variables for QOL (p < 0.05). Although this study reveals good overall QOL for individuals after PTG, attention should be given to managing symptoms as part of long term care to further enhance QOL. The function/symptom scores were associated with worse overall health and global health status and thus may mark a real need for more attentive post-surgical care.

Germline CDH1 mutations are a significant contributor to the high frequency of early-onset diffuse gastric cancer cases in New Zealand M\u0101ori

New Zealand Māori have a considerably higher incidence of gastric cancer compared to non-Māori, and are one of the few populations worldwide with a higher prevalence of diffuse-type disease. Pathogenic germline CDH1 mutations are causative of hereditary diffuse gastric cancer, a cancer predisposition syndrome primarily characterised by an extreme lifetime risk of developing diffuse gastric cancer. Pathogenic CDH1 mutations are well described in Māori families in New Zealand. However, the contribution of these mutations to the high incidence of gastric cancer is unknown. We have used next-generation sequencing, Sanger sequencing, and Multiplex Ligation-dependent Probe Amplification to examine germline CDH1 in an unselected series of 94 Māori gastric cancer patients and 200 healthy matched controls. Overall, 18% of all cases, 34% of cases diagnosed with diffuse-type gastric cancer, and 67% of cases diagnosed aged less than 45 years carried pathogenic CDH1 mutations. After adjusting for the effect of screening known HDGC families, we estimate that 6% of all advanced gastric cancers and 13% of all advanced diffuse-type gastric cancers would carry germline CDH1 mutations. Our results demonstrate that germline CDH1 mutations are a significant contributor to the high frequency of diffuse gastric cancer in New Zealand Māori.

Abstract 1282: Genetic basis of hereditary gastric cancer: Beyond the CDH1 locus

Abstract Importance. Hereditary gastric cancer (HGC) is a rare, autosomal dominant susceptibility syndrome characterized either by early onset diffuse gastric cancer and lobular breast cancer or aggregates of intestinal gastric cancer. The genetic etiology of &amp;lt;50% of families classified as hereditary diffuse gastric cancer (HDGC) can be attributed to pathogenic germline mutations in the gene CDH1 (which encodes a crucial cellular adhesion molecule, E-cadherin). Unfortunately, the genetic basis of CDH1-negative HDGC families and all familial intestinal gastric cancers is unknown. Objectives. 1) Determine whether pathogenic germline mutations in genes related to upper gastrointestinal disorders (UGI) are causative in HGC and 2) show that a targeted multiplexed next generation sequencing approach is effective and efficient for detecting such mutations. Methods &amp; Participants. 115 probands from families who met clinical criteria for HDGC (n=108) or FIGC (n=7) were included. HDGC participants have all previously tested negative for CDH1 variants. A custom panel of 55 genes previously associated with heritable UGI disorders was designed through literature research and collaborative efforts. The germline DNA of probands from each family was sequenced for all targeted regions using the MiSeq platform. Candidate variants were selected based on likelihood of pathogenicity (protein truncating, rare/novel pathogenic missense variants) then validated via Sanger sequencing. Tumour materials from mutation-carriers were analyzed for loss of heterozygosity via immunohistochemistry and/or second hit analysis. When available, germline DNA of additional family members was collected for segregation analysis. Results. We have identified clearly pathogenic mutations in unrelated HGC families, including two protein truncating mutations each in CTNNA1 and BRCA2 genes and two rare, pathogenic missense mutations each in SDHB and STK11 genes. Additional protein truncating mutations were identified in moderately penetrant genes ATM (4 families), MSR1 (2 families), and PALB2 (1 family). Overall, 13% of families included in this study were found to have pathogenic (8) or likely pathogenic (7) mutations in genes included on our custom panel. Tumour material was available from probands with truncating CTNNA1 variants, revealing distinct loss of protein expression using immunohistochmistry. This further supports the likelihood of pathogenicity. Conclusion &amp; Relevance. Using a targeted next generation sequencing approach that significantly reduced sequencing cost while simultaneously improving turn-around time, we show that HGC families can carry pathogenic mutations outside the CDH1-locus, including genes commonly associated with other UGI syndromes. The genetic basis of the remaining families likely lies in yet to be discovered susceptibility genes or, in the case of HDGC, additional abnormalities at the CDH1-locus. Citation Format: Samantha Hansford, Hector LiChang, Pardeep Kaurah, Michelle Woo, Karey Shumansky, David F. Schaeffer, Giovanni Corso, George Zogopoulos, Steven Gallinger, Hugo Pinheiro, Franco Roviello, Carla Oliveira, David Huntsman. Genetic basis of hereditary gastric cancer: Beyond the CDH1 locus. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1282. doi:10.1158/1538-7445.AM2014-1282

Detection of CDH1 gene variants in early-onset diffuse gastric cancer in Chinese patients.

e15079 Background: To study the correlation between the type and frequency of exon variants in E- cadherin (CDH1) gene and clinical characteristics of early-onset diffuse gastric cancer (EODGC) in ...

Searching for CDH1 gene mutations in early-onset diffuse gastric cancer in Chinese patients.

23 Background: CDH1 germline mutations are found to be associated with the development of hereditary diffuse gastric cancer (HDGC) and the early-onset diffuse gastric cancer (EODGC). But the impact of CDH1 gene mutations and large deletions on HDGC and EODGC has not been fully determined in Asians. Although the incidence of gastric cancer is relatively high in China, the detection rate of CDH1 germline mutations in Chinese patients with EODGC is rare compared to that in European patients. Methods: We investigated the mutation status of the CDH1 gene in 57 Chinese EODGC patients younger than 40 years old who met the clinical criteria for HDGC. Polymerase chain reaction-direct sequencing was performed, and multiplex ligation-dependent probe amplification (MLPA) was used to evaluate the patients with negative sequencing results. Associations between mutation, clinicopathologic, and overall survival data were analyzed by SPSS 19. Results: The germline mutations of CDH1gene were identified in 51 (89.5%) of the 57 EODGC patients. The nonsense mutation in exon 13 (c.2200T&gt;C, p.Ala692*) occurred in fourty-six EODGC patients. The missense mutations were detected in twenty patients (Eighteen in exon 5: c.778G&gt;C, p.Glu218Asp; Two in exon 12: c.2012C&gt;G, p.Leu630Val). No deletion or duplication in any patient. Most of the patients carrying the CDH1 mutation in exon 13 had lymph node metastasis when compared with patients lacking CDH1 mutation (87.2% vs 60.0%) ( P &lt; 0.05 ). EODGC patients, lacking germline CDH1 alterations, showed a longer median overall survival (mOS) than patients carrying CDH1 mutation in exon 13 ( P &lt; 0.05 ). Moreover, the presence of CDH1 mutation in exon 13 was associated with the incidence of neural invasion ( P &lt; 0.05 ). Conclusions: This study reveals novel CDH1 mutations in Chinese EODGC patients which had been poorly investigated. The presence of CDH1 mutation in EODGC patients may result in lymph node metastasis and poor prognosis. More research is needed to determine additional genetic targets that trigger EODGC.

Detection of CDH1 gene variants in early-onset diffuse gastric cancer in Chinese patients.

The type and frequency of E-cadherin (CDH1) germline variants in China for the early-onset diffuse gastric cancer (EODGC) has not been well established. Our study tend to screen and characterize germline variants for CDH1 gene in EODGC patients and in general population in China. Peripheral blood samples were collected from 57 EODGC patients (age ≤ 40 years) who underwent resection surgery for primary gastric cancer. DNA was extracted from peripheral blood leucocytes and polymerase chain reaction amplification (PCR) was performed to amplify and sequence the CDH1 gene. Statistical analysis was performed using the SPSS 19 software. CDH1 genetic screening results: 2 missense in exon 5 (c.778G > C, 26.3%) and 12 (c.2012C > G, 1.8%), and 1 synonymous (c.2200T > C, 72.8%) in exon 13. According to the c.2200T > C variant, the CDH1 C frequency was 62.3% and the T frequency 37.7%, while the CC homozygote frequency was 43.9%, the TT homozygote 19.3% and the CT heterozygote 36.8%. According to the c.778G > C variant, the CDH1 C frequency was 15.8% and the G frequency 84.2%, while the GG homozygote frequency was 68.4%, the GC heterozygote 31.6%. When comes to the c.2012C > G variant, the CDH1 C frequency was 98.2% and the G frequency 1.8%, while the CC homozygote frequency was 96.5%, the GC heterozygote 3.5%. Statistical association was analyzed among the EODGC patients and BDs group tested for the three variants. Lymph node metastasis rate was found to be significantly higher in patients with c.2200T > C (P = 0.04). The difference in OS with or without c.2200T > C variant was found to be sig- nificant (P < 0.05). No deletions or insertions were found in the CDH1 exon boundaries. All of the variants resulted com- mon polymorphisms. CDH1 germline variants are present in EODGC patients in Chinese population, but they are mainly missense variants with unknown function which are likely associated with lymph node metastasis and OS.

Early-onset diffuse gastric cancer associated with a de novo large genomic deletion of CDH1 gene

A 41-year-old man with no familial history of gastric cancer was diagnosed as with intramucosal early gastric cancer. Two months after the first endoscopic submucosal dissection for signet-ring cell carcinoma (SRCC), the appearance of previously unrecognized multiple erosions of SRCC was noticed. Pathological examination after a total gastrectomy and Roux-en-Y reconstruction with D2 lymph node dissection were performed. Postoperative pathological examination revealed 90 and more lesions, which tempted the attending pathologist to refer to genetic tests for the predisposition though the patient had no familial history of gastric cancer. There were no mutations in all the exons of CDH1 with conventional DNA sequencing, but multiplex ligation-dependent probe amplification, and reverse transcription-polymerase chain reaction analyses disclosed a large genomic deletion (c.1566-?_1711+?del), leading to the mRNA with loss of the exon 11. Among family members, his son was found to be a carrier of this change, while his parents were negative for the familial CDH1 mutation, implying that this change is a de novo event in the proband. The present report is the first description of a de novo large genomic deletion of CDH1 gene associated with early-onset diffuse gastric cancer. When the clinician finds a relatively-young patient who has multiple SRCCs, CDH1 germline mutation should be considered, even for patients with no familial history.

Searching for E-cadherin gene mutations in early onset diffuse gastric cancer and hereditary diffuse gastric cancer in Korean patients

The impact of CDH1 gene mutations and large deletions on hereditary diffuse gastric cancer (HDGC) and early onset diffuse gastric cancer (EODGC) has not been determined in Asians. We investigated the mutation status of the CDH1 gene in 25 Korean EODGC patients younger than 50 years and 23 HDGC patients who met the clinical criteria for HDGC. Polymerase chain reaction-direct sequencing was performed, and multiplex ligation-dependent probe amplification (MLPA) was used to evaluate the patients with negative sequencing results. We determined that 2 of 25 (8 %) EODGC patients had CDH1 germline mutations. One was a nonsense mutation (c.1003C>T, p.Arg335*, exon 7) in a 41-year-old female with no family history of cancer. The other was a missense mutation (c.715G>A, p.Gly239Arg, exon 6) in a 28-year-old male with no family history of cancer. One of 23 (4.3 %) HDGC patients had a CDH1 germline mutation (c.1003C>T). The patient's brother and sister died of stomach cancer. The MLPA results revealed no deletion or duplication in any patient. More research is needed to determine additional genetic targets that trigger HDGC. More comprehensive methods such as next-generation sequencing might be a good approach that can be used to identify the genetic causes of pathogenetically unexplained disorders.

E-cadherin genetic screening and clinico-pathologic characteristics of early onset gastric cancer

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 ⩽50 years. 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 35 years 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.

Allele-specific CDH1 downregulation and hereditary diffuse gastric cancer

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant cancer susceptibility syndrome characterized by early-onset diffuse gastric cancer (DGC) and lobular breast cancer. E-cadherin (CDH1) heterozygous germline mutations and deletions are found in 40% of families. Independent of CDH1 alterations, most HDGC tumours display mislocalized or absent E-cadherin immunoexpression, therefore undetected defects at the CDH1 locus may still be involved. We aimed at determining whether CDH1 mutation-negative probands display germline CDH1 allele-specific expression (ASE) imbalance, using a single-nucleotide primer extension-based procedure and tried to uncover the underlying molecular defect. CDH1 ASE analysis was performed using three intragenic SNPs in RNA extracted from the blood of 21 cancer-free individuals and 22 HDGC probands (5 CDH1 mutation carriers and 17 CDH1 negative). Germline promoter methylation, deletions and haplotype-related susceptibility at the CDH1 locus were analysed. Both CDH1 alleles from cancer-free individuals displayed equivalent expression levels, whereas monoallelic CDH1 expression or high allelic expression imbalance (AI) was present in 80% of CDH1 mutant and 70.6% (n = 12) of CDH1-negative HDGC probands. Germline deletions and promoter hypermethylation were found in 25% of probands displaying high CDH1 AI. No particular haplotype was found to be associated with CDH1 high AI. Germline CDH1 AI is highly frequent among CDH1 mutation-negative probands but was not seen in cancer-free individuals. This implicates the CDH1 locus in the majority of mutation-negative HDGC families.

Hereditary Gastric Carcinoma: At Management Cross Roads

Introduction: Hereditary diffuse gastric cancer (HDGC) is an autosomal-dominant cancer susceptibility syndrome characterized by early onset diffuse gastric cancer and lobular breast cancer. Germ-line truncating mutations in the E-cadherin gene (CDH1) have been shown to underlie about 30% of HDGC families of various ethnic backgrounds. Here, we report a family with HDGC.FigureCase 1: A 69- year-old, female with a history of familial gastric and breast carcinoma, was diagnosed with lobular carcinoma of right breast at 43 years of age. Genetic screening for BRCA1 and BRCA2 was negative. Full sequencing of CDH1 gene done last year was positive for 2287G>T deleterious mutation. Since then she is under chromoendoscopic surveillance at six monthly interval, as she is still weighing the offer of prophylactic gastrectomy. Detailed family history was obtained and pedigree constructed (Fig. 1). Case 2: A 55-year-old, female presented for consultation about being tested positive for CDH1 gene mutation. She was found to be the first cousin of case 1 and having same deleterious mutation of CDH1 gene at the same locus. She under went EGD and was discovered to have linitis plastica with histology revealing invasive, poorly differentiated adenocarcinoma, signet cell type. Patient is now ongoing evaluation for total gastric resection. Discussion: Germline CDH1-associated gastric cancer develops diffusely throughout the stomach wall and foci of malignant cells often underlie a grossly and histologically normal surface epithelium. Therefore serial conventional EGD, chromoendoscopy or endoscopic ultrasound may not be a useful screen for this patient population. Our cases illustrate the controversies surrounding the optimal management of germline E-cadherin mutation patients and their families. The average age of onset of gastric cancer in germline CDH1- positive families is 38 years, but it has been documented in teens as well. The question arises as to what is the ideal timing for surgical intervention and screening, given our case 1 has been asymptomatic up till now but on the other hand, case 2 being already positive for malignancy.[figure1]