Implication of DNA repair genes in Lynch-like syndrome

AbstractMany colorectal cancers (CRCs) that exhibit microsatellite instability (MSI) are not explained byMLH1 promoter methylation or germline mutations in mismatch repair (MMR) genes, which cause Lynch syndrome (LS). Instead, these Lynch-like syndrome (LLS) patients have somatic mutations in MMR genes. However, many of these patients are young and have relatives with cancer, suggesting a hereditary entity. We performed germline sequence analysis in LLS patients and determined their tumor ’s mutational profiles using FFPE DNA. Six hundred and fifty-four consecutive CRC patients were screened for suspected LS using MSI and absence ofMLH1 methylation. Suspected LS cases were exome sequenced to identify germline and somatic mutations. Single nucleotide variants were used to characterize mutational signatures. We identified 23 suspected LS cases. Germline sequence analysis of 16 available samples identified five cases with LS mutations and 11 cases without LS mutations, LLS. Most LLS tumors had a combination of somatic MMR gene mutation and loss of heterozygosity. LLS patients were relatively young and had excess first-degree relatives with cancer. Four of the 11 LLS patients had rare likely pathogenic variants in genes that maintain genome integrity. Moreover, tumors from this group had a distinct mutational signature compared to tumors from LLS patients lacking germline mutations in these genes. In summary, more than a third of the LLS patients studied had germline mutati...
Source: Familial Cancer - Category: Cancer & Oncology Source Type: research

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CONCLUSIONS: Universal tumour testing strategies for guiding germline genetic testing of people with incident CRC for LS in Australia are likely to be cost-effective compared with no testing. Universal germline gene panel testing would not currently be cost-effective. PMID: 31595523 [PubMed - as supplied by publisher]
Source: Medical Journal of Australia - Category: General Medicine Tags: Med J Aust Source Type: research
Abstract About 5% of colorectal cancer (CRC) cases occurred in the context of an underlying hereditary predisposition syndrome. Lynch syndrome is the main causes of hereditary CRC but is also associated with a higher risk of other cancers (such as endometrial cancer and ovarian cancer). It is the consequence of constitutional mutation in a MisMatch Repair (MMR) gene, involved in DNA repair: MLH1, MSH2, MSH6 or PMS2; or of the EPCAM gene (MSH2 promotor). If a mutation predisposing to Lynch Syndrome is identified in an individual, special monitoring should be initiated, adapted to estimated cancer risk. Clinical cri...
Source: Presse Medicale - Category: General Medicine Authors: Tags: Presse Med Source Type: research
ConclusionFurther studies should be conducted to provide new insights about survival of colorectal carcinoma in Lynch syndrome, as well as the therapeutic alternatives for this neoplasia.ResumoIntroduçãoO carcinoma colorretal é a terceira neoplasia mais prevalente no mundo, bem como a segunda causa de morte por câncer. A maioria destas neoplasias são esporádicas, devidas a mutações somáticas, mas cerca de 15% são hereditárias como a síndrome de Lynch ou Hereditary Nonpolyposis Colorectal Cancer (HNPCC). Apesar de ser a mesma neoplasia, esta ...
Source: Journal of Coloproctology - Category: Gastroenterology Source Type: research
This study aimed to investigate the spectrum of germ-line mutations in Russian LS patients. LS-related mismatch repair (MMR) genes were analyzed in 16 patients, who were forwarded to genetic testing due to strong clinical features of LS and had high-level microsatellite instability (MSI-H) in the tumor (n = 14) or unknown MSI status (n = 2). In addition, 672 consecutive colorectal cancer (CRC) cases were screened for family history; 15 patients were younger than 50 years and reported 2 or more instances of LS-related cancers in 1st- or 2nd-degree relatives. Seven of these cases demonstrated MSI-H and th...
Source: European Journal of Medical Genetics - Category: Genetics & Stem Cells Authors: Tags: Eur J Med Genet Source Type: research
Patients with Lynch syndrome are offered the same colorectal cancer (CRC) surveillance programs (colonoscopy every 2 years), regardless of the pathogenic DNA mismatch repair gene variant the patient carries. We aimed to assess the yield of surveillance for patients with these variants in MLH1, MSH2, MSH6, and PMS2.
Source: Clinical Gastroenterology and Hepatology - Category: Gastroenterology Authors: Source Type: research
Publication date: Available online 21 August 2019Source: Journal of Visceral SurgeryAuthor(s): B. Menahem, A. Alves, J.M. Regimbeau, C. SabbaghSummaryNearly 5% of colorectal cancers are related to constitutional genetic abnormalities. In Lynch Syndrome (LS), the abnormality is a mutation of the deoxyribonucleic acid (DNA) repair system. The goal of this update is to update indications and surgical strategies for patients with LS. Different spectra of disease are associated with LS. The narrow spectrum includes cancers with a high relative risk: colorectal cancer (CRC), endometrial cancer, urinary tract cancers and small in...
Source: Journal of Visceral Surgery - Category: Surgery Source Type: research
We report the case of a Lynch syndrome patient with metastatic CRC and urothelial cancer who was treated sequentially with pembrolizumab (targeting PD1), atezolizumab (targeting PD-L1), brief rechallenge with pembrolizumab, and finally the combination of ipilimumab (targeting CTLA-4) and nivolumab (targeting PD1). Over a 28-month period the patient experienced prolonged disease control with each different regimen the first time it was given, including metabolic response by positron emission tomography and computed tomography scanning and tumor marker reductions. The case suggests that some patients with advanced MMR-defici...
Source: The Oncologist - Category: Cancer & Oncology Authors: Tags: Oncologist Source Type: research
Abstract MMR-deficient colorectal cancers (dMMR CRC) are characterized by the expression of highly-immunogenic neoantigen peptides, which stimulate lymphocytic infiltration as well as up-regulation of inflammatory cytokines. These features are key to understanding why immunotherapy (specifically PD-1 and/or CTLA-4 checkpoint blockade) has proved to be highly effective for the treatment of patients with advanced dMMR CRC. Importantly, pre-clinical studies also suggest that this correlation between potent tumor neoantigens and the immune microenvironment is present in early (pre-malignant) stages of dMMR colorectal ...
Source: Clinical Cancer Research - Category: Cancer & Oncology Authors: Tags: Clin Cancer Res Source Type: research
In this study, we follow the diagnostic journey of a 12-year old patient with CRC, with a clinical phenotype overlapping CMMRD. We perform molecular and functional assays to discard a CMMRD diagnosis then identify by exome sequencing and validation in a cohort of 134 LS patients, a candidate variant in the MLH1 UTR region in homozygosis. We propose that this variant, together with other candidates, could be responsible for age-of-onset modulation. Our data support the idea that low-risk modifier alleles may influence early development of cancer in LS leading to a LS-to-CMMRD phenotypic continuum. Therefore, it is essential...
Source: Cancers - Category: Cancer & Oncology Authors: Tags: Communication Source Type: research
Lynch Syndrome (LS) is a dominantly inherited condition with incomplete penetrance, characterized by high predisposition to colorectal cancer (CRC), endometrial and ovarian cancers, as well as to other tumors. LS is associated with constitutive DNA mismatch repair (MMR) gene defects, and carriers of the same pathogenic variants can show great phenotypic heterogeneity in terms of cancer spectrum. In the last years, human gut microbiota got a foothold among risk factors responsible for the onset and evolution of sporadic CRC, but its possible involvement in the modulation of LS patients’ phenotype still needs to be inv...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research
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