Screening for germline mutations in mismatch repair genes in patients with Lynch syndrome by next generation sequencing

AbstractLynch syndrome (LS) is an autosomal dominant disorder, with high penetrance that affects approximately 3% of the cases of colorectal cancer. Affected individuals inherit germline mutations in genes responsible for DNA mismatch repair, mainly atMSH2, MLH1, MSH6 andPMS2. The molecular screening of these individuals is frequently costly and time consuming due to the large size of these genes. In addition,PMS2 mutation detection is often a challenge because there are 16 different pseudogenes identified until now. In the present work we evaluate a molecular screening strategy based in next generation sequencing (NGS) in order to optimize the mutation detection in LS patients. We established 16 multiplex PCRs forMSH2, MSH6 andMLH1 and 5 Long-Range PCRs forPMS2, coupled with NGS. The strategy was validated by screening 66 patients who filled Bethesda and Amsterdam criteria for LS from health institutions of Brazil. The mean depth of coverage forMSH2, MSH6, MLH1 andPMS2 genes was 7.988, 36.313, 11.899 and 4.772 times, respectively. Ninety-four variants were found in exons and flanking intron/exon regions for the four MMR genes. Twenty-five were pathogenic or VUS and found in 32 patients (7 inMSH2, 5 inMSH6, 12 inMLH1 e 1 inPMS2). All variants were confirmed by Sanger sequencing. The strategy was efficient to reduce time consuming and costs to identify genetic changes at these MMR genes, reducing in three times the number of PCR reactions performed per patient and was efficien...
Source: Familial Cancer - Category: Cancer & Oncology Source Type: research

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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...
Source: The Oncologist - Category: Cancer & Oncology Authors: Tags: Precision Medicine Clinic: Molecular Tumor Board, Gastrointestinal Cancer Precision Medicine Clinic: Molecular Tumor Boards Source Type: research
Since 2017, the National Institute for Health and Care Excellence (NICE) has recommended molecular testing of all patients with newly diagnosed colorectal cancer (CRC) to identify those with suspected Lynch syndrome who should be referred to clinical genetics for germline testing. The pathway involves firstly determining the mismatch repair (MMR) expression status by immunohistochemistry (IHC) or performing microsatellite instability testing. This may be followed by BRAF V600E mutation testing and then MLH1 promoter hypermethylation analysis depending on the result.
Source: Diagnostic Histopathology - Category: Pathology Authors: Tags: Mini-symposium: Gastrointestinal/Hepato-Pancreato-Biliary Pathology Source Type: research
Conclusions: Our results suggest that transcriptional patterns are indicative for TMM pathway activation with subtle differences between TEL and ALT mechanisms in a CRC subtype-specific fashion. Sequencing data potentially provide a suited measure to study alterations of telomere length and of underlying transcriptional regulation. Further studies are needed to improve this method.
Source: Frontiers in Oncology - Category: Cancer & Oncology Source Type: research
AbstractPurpose of reviewIdentification of Lynch syndrome is important from an individual patient and public health standpoint. As paradigms for Lynch syndrome diagnosis have shifted in recent years, this review will discuss rationale and limitations for current strategies as well as provide an overview of future directions in the field.Recent findingsIn recent years, the use of clinical criteria and risk scores for identification of Lynch syndrome has been augmented by universal testing of all newly diagnosed colorectal cancers with molecular methods to screen for mismatch repair deficiency with high sensitivity and speci...
Source: Current Treatment Options in Gastroenterology - Category: Gastroenterology Source Type: research
Lynch syndrome (LS) is an autosomal dominant hereditary cancer predisposition syndrome caused by pathogenic germline variants in DNA mismatch repair genes (MMR) MLH1, MSH2, MSH6 and PMS2. LS accounts for 3 –5% of all colorectal cancers (CRC). LS associated CRC generally has microsatellite instability and lacks for MMR protein expression. The risk of CRC in LS patients is between 10 and 82% depending on the involved MMR gene. LS patients are at high risk to develop synchronous/metachronous cancer bot h colonic and extracolonic (e.g.
Source: Digestive and Liver Disease - Category: Gastroenterology Authors: Tags: Correspondence Source Type: research
ConclusionWe found a novel largeEPCAM-MSH2 duplication associated with LS and the presence of LOHs in regions containing numerous tumor suppressors, raising the hypothesis that these alterations could contribute to cancer susceptibility. Our results underline the importance to deepen the knowledge of molecular mechanisms in order to determine the role in cancer predisposition of novel genetic alterations.
Source: International Journal of Colorectal Disease - Category: Gastroenterology Source Type: research
ConclusionsSporadic dMMR breast cancers are extremely rare (Davies et al. in Cancer Res 77:4755 –4762, 2017). It seems reasonable to conclude that identifying a dMMR breast cancer in a patient with known LS strongly suggests that her LS is breast cancer-predisposing. LS patients with dMMR breast cancers might therefore be considered for above-average breast cancer screening for the developme nt of additional breast cancers. Also, the FDA recently granted approval of checkpoint inhibitor therapy for all metastatic dMMR solid malignancies (Lemery et al. in N Engl J Med 377:1409–1412, 2017). MMR expression assays ...
Source: Breast Cancer Research and Treatment - Category: Cancer & Oncology Source Type: research
ConclusionTo optimize targeting and visualization of the surgical field in right pelvic sidewall/paracolic gutter, robotic arms can be placed in a straight line from above the pubic symphysis extending to the left subcostal line and between the midline vertical and midclavicular lines. Robotic tumor debulking should be considered in selected patients with recurrent ovarian cancer who present with oligo-metastatic disease, in the absence of carcinomatosis.
Source: Journal of Minimally Invasive Gynecology - Category: OBGYN Source Type: research
Tougeron Tumor DNA mismatch repair (MMR) deficiency testing is important to the identification of Lynch syndrome and decision making regarding adjuvant chemotherapy in stage II colorectal cancer (CRC) and has become an indispensable test in metastatic tumors due to the high efficacy of immune checkpoint inhibitor (ICI) in deficient MMR (dMMR) tumors. CRCs greatly benefit from this testing as approximately 15% of them are dMMR but only 3% to 5% are at a metastatic stage. MMR status can be determined by two different methods, microsatellite instability (MSI) testing on tumor DNA, and immunohistochemistry of the MMR pro...
Source: Cancers - Category: Cancer & Oncology Authors: Tags: Review Source Type: research
AbstractBackgroundWe previously reported that in pathogenic mismatch repair (path_MMR) variant carriers, the incidence of colorectal cancer (CRC) was not reduced when colonoscopy was undertaken more frequently than once every 3 years, and that CRC stage and interval since last colonoscopy were not correlated.MethodsThe Prospective Lynch Syndrome Database (PLSD) that records outcomes of surveillance was examined to determine survival after colon cancer in relation to the time since previous colonoscopy and pathological stage. Onlypath_MMR variants scored by the InSiGHT variant database as class 4 or 5 (clinically actionable...
Source: Hereditary Cancer in Clinical Practice - Category: Cancer & Oncology Source Type: research
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