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Early-onset breast cancer in a Lebanese family with Lynch syndrome due to MSH2 gene mutation.

ABSTRACT: BACKGROUND:There are still controversies about the integration of breast cancer as a part of the disease spectrum in Lynch syndrome. METHODS:A regular follow-up of a Lebanese pedigree with Lynch syndrome due to a point mutation of MSH2 gene at the splice donor site of intron 3 started in 1996. RESULTS:A 26-year-old pregnant woman, mutation carrier, developed an aggressive breast cancer, refractory to standard chemotherapy regimens. The microsatellite analysis of the tumor showed an unstable pattern for markers BAT25 and BAT26. The immunohistochemical staining was negative for MSH2 and MSH6 and normal for MLH1 and PMS6 enzymes. CONCLUSION:The segregation of the mutation with the disease phenotype and these results suggest that MSH2 inactivation may be involved in the accelerated breast carcinogenesis and might be considered in the cancer screening program.

SUBMITTER: Akoum R

PROVIDER: S-EPMC2692982 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature

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Early-onset breast cancer in a Lebanese family with Lynch syndrome due to MSH2 gene mutation.

Akoum Riad R Ghaoui Albert A Brihi Emile E Ghabash Maroun M Hajjar Nicolas N

Hereditary cancer in clinical practice 20090528 1

<h4>Background</h4>There are still controversies about the integration of breast cancer as a part of the disease spectrum in Lynch syndrome.<h4>Methods</h4>A regular follow-up of a Lebanese pedigree with Lynch syndrome due to a point mutation of MSH2 gene at the splice donor site of intron 3 started in 1996.<h4>Results</h4>A 26-year-old pregnant woman, mutation carrier, developed an aggressive breast cancer, refractory to standard chemotherapy regimens. The microsatellite analysis of the tumor s ...[more]

PMID: 19476642

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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.

Project description:INTRODUCTION: Several studies evaluated the prevalence of Lynch Syndrome (LS) in young onset colorectal cancer (CRC) patients and the results were extremely variable (5%-20%). Immunohistochemistry (IHC) for MMR proteins and/or MSI analysis are screening tests that are done, either by themselves or in conjunction, on colon cancer tissue to identify individuals at risk for LS. The primary aim of our study was to evaluate the prevalence of LS in a large series of early-onset CRC without family history compared with those with family history. The secondary aim was to assess the diagnostic accuracy of IHC and MSI analysis as pre-screening tools for LS. METHODS: Early-onset CRC patients (? 50 years) were prospectively recruited in the study. IHC and MSI analysis were performed in all the patients. Germ-line mutation analysis (GMA) was carried out in all MMR deficient tumors. A logistic regression model was performed to identify clinical features predictive of MSI-H. RESULTS: 117 early onset CRC cases were categorized in three groups (A, B, C) according with family history of CRC. IHC and MSI analysis showed MMR deficiency in 6/70 patients (8.6%) of group A, 24/40 patients (60%) of group B and none of group C. GMA showed a deleterious mutation in 19 (47.5%) patients of group B. MSI analysis had a diagnostic accuracy of 95.7% (CI 92.1-99.4) and IHC of 83.8% (CI 77.1-90.4). The logistic regression model revealed that by using a combination of the two features "No Amsterdam Criteria" and "left sided CRC" to exclude MSI-H, accuracy was 89.7% (84.2-95.2). CONCLUSIONS: Early-onset CRC patients, with left sided CRC and without family history are "at very low risk" for Lynch syndrome. The two simple criteria of family history and CRC site could be used as a pre-screening tool to evaluate whether or not patients should undergo tissue molecular screening. In the few cases of suspected LS (right sided CRC and/or Amsterdam Criteria), a reasonable approach could be to perform MSI analysis first and IHC afterwards only in MSI-H patients.

Dataset Information

Early-onset breast cancer in a Lebanese family with Lynch syndrome due to MSH2 gene mutation.

Publications

Early-onset breast cancer in a Lebanese family with Lynch syndrome due to MSH2 gene mutation.

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