Dataset Information

A Hereditable Mutation of MSH2 Gene Associated with Lynch Syndrome in a Five Generation Chinese Family.

ABSTRACT: Purpose:In order to clarify which variants of the MMR gene could provide current "healthy" members in affected families a more accurate risk assessment or predictive testing. Patients and Methods:One family, which meets the criteria according to both Amsterdam I/II and Bethesda guidelines, is reported in this study. The proband and some relatives of the patient have been investigated for whole genome sequencing, microsatellite instability, immunohistochemical MMR protein staining and verified by Sanger sequencing. Results:A heterozygous insertion of uncertain significance (c.420dup, p.Met141Tyrfs) in MSH2 gene was found in proband (III-16) and part of His relatives. The variant was associated with a lack of expression of MSH2 protein (MMR deficient) and high microsatellite instability analysis (MSI) status in tumor tissues of LS patients. In addition, we found that the variant could affect the expression of MSH2 and the response to chemotherapy drugs in vitro. Conclusion:We identified an insertion mutation (rs1114167810, c.420dup, p.Met141Tyrfs) in MSH2 in LS using whole genome-wide sequencing (WGS). We further confirmed that this mutation plays an important role in LS patients of this pedigree based on in vivo and vitro study.

SUBMITTER: Shao WH

PROVIDER: S-EPMC7051253 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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A Hereditable Mutation of MSH2 Gene Associated with Lynch Syndrome in a Five Generation Chinese Family.

Shao Wei-Hua WH Wang Cheng-Yu CY Wang Lei-Yun LY Xiao Fan F Xiao De-Sheng DS Yang Hao H Long Xue-Ying XY Zhang Le L Luo Heng-Gui HG Yin Ji-Ye JY Wu Wei W

Cancer management and research 20200227

<h4>Purpose</h4>In order to clarify which variants of the MMR gene could provide current "healthy" members in affected families a more accurate risk assessment or predictive testing.<h4>Patients and methods</h4>One family, which meets the criteria according to both Amsterdam I/II and Bethesda guidelines, is reported in this study. The proband and some relatives of the patient have been investigated for whole genome sequencing, microsatellite instability, immunohistochemical MMR protein staining ...[more]

PMID: 32161499

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Project description:BACKGROUND:Lynch syndrome (LS) is a highly penetrant inherited cancer predisposition syndrome, characterized by autosomal dominant inheritance and germline mutations in DNA mismatch repair genes. Despite several genetic variations that have been identified in various populations, the penetrance is highly variable and the reasons for this have not been fully elucidated. This study investigates whether, besides pathogenic mutations, environment and low penetrance genetic risk factors may result in phenotype modification in a Tunisian LS family. PATIENTS AND METHODS:A Tunisian family with strong colorectal cancer (CRC) history that fulfill the Amsterdam I criteria for the diagnosis of Lynch syndrome was proposed for oncogenetic counseling. The index case was a man, diagnosed at the age of 33 years with CRC. He has a monozygotic twin diagnosed at the age of 35 years with crohn disease. Forty-seven years-old was the onset age of his paternal uncle withCRC. An immunohistochemical (IHC) labeling for the four proteins (MLH1, MSH2, MSH6 and PMS2) of the MisMatchRepair (MMR) system was performed for the index case. A targeted sequencing of MSH2, MLH1 and a panel of 85 DNA repair genes was performed for the index case and for his unaffected father. RESULTS:The IHC results showed a loss of MSH2 but not MLH1, MSH6 and PMS2 proteins expression. Genomic DNA screening, by targeted DNA repair genes sequencing, revealed an MSH2 pathogenic mutation (c.1552C>T; p.Q518X), confirmed by Sanger sequencing. This mutation was suspected to be a causal mutation associated to the loss of MSH2 expression and it was found in first and second degree relatives. The index case has smoking and alcohol consumption habits. Moreover, he harbors extensive genetic variations in other DNA-repair genes not shared with his unaffected father. CONCLUSION:In our investigated Tunisian family, we confirmed the LS by IHC, molecular and in silico investigations. We identified a novel pathogenic mutation described for the first time in Tunisia. These results come enriching the previously reported pathogenic mutations in LS families. Our study brings new arguments to the interpretation of MMR expression pattern and highlights new risk modifiers genes eventually implicated in CRC. Twins discordance reported in this work underscore that disease penetrance could be influenced by both genetic background and environmental factors.

Dataset Information

A Hereditable Mutation of MSH2 Gene Associated with Lynch Syndrome in a Five Generation Chinese Family.

Publications

A Hereditable Mutation of MSH2 Gene Associated with Lynch Syndrome in a Five Generation Chinese Family.

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