| Selection of patients with germline MLH1 mutated Lynch syndrome by determination of MLH1 methylation and BRAF mutation. | |
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MedLine Citation:
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PMID: 19949877 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Lynch syndrome is one of the most common hereditary colorectal cancer (CRC) syndrome and is caused by germline mutations of MLH1, MSH2 and more rarely MSH6, PMS2, MLH3 genes. Whereas the absence of MSH2 protein is predictive of Lynch syndrome, it is not the case for the absence of MLH1 protein. The purpose of this study was to develop a sensitive and cost effective algorithm to select Lynch syndrome cases among patients with MLH1 immunohistochemical silencing. Eleven sporadic CRC and 16 Lynch syndrome cases with MLH1 protein abnormalities were selected. The BRAF c.1799T> A mutation (p.Val600Glu) was analyzed by direct sequencing after PCR amplification of exon 15. Methylation of MLH1 promoter was determined by Methylation-Sensitive Single-Strand Conformation Analysis. In patients with Lynch syndrome, there was no BRAF mutation and only one case showed MLH1 methylation (6%). In sporadic CRC, all cases were MLH1 methylated (100%) and 8 out of 11 cases carried the above BRAF mutation (73%) whereas only 3 cases were BRAF wild type (27%). We propose the following algorithm: (1) no further molecular analysis should be performed for CRC exhibiting MLH1 methylation and BRAF mutation, and these cases should be considered as sporadic CRC; (2) CRC with unmethylated MLH1 and negative for BRAF mutation should be considered as Lynch syndrome; and (3) only a small fraction of CRC with MLH1 promoter methylation but negative for BRAF mutation should be true Lynch syndrome patients. These potentially Lynch syndrome patients should be offered genetic counselling before searching for MLH1 gene mutations. |
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Authors:
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Hanifa Bouzourene; Pierre Hutter; Lorena Losi; Patricia Martin; Jean Benhattar |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Familial cancer Volume: 9 ISSN: 1573-7292 ISO Abbreviation: Fam. Cancer Publication Date: 2010 Jun |
Date Detail:
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Created Date: 2010-05-17 Completed Date: 2010-09-15 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100898211 Medline TA: Fam Cancer Country: Netherlands |
Other Details:
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Languages: eng Pagination: 167-72 Citation Subset: IM |
Affiliation:
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Institute of Pathology, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Bugnon 25, 1011, Lausanne, Switzerland. Hanifa.Bouzourene@chuv.ch |
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| MeSH Terms | |
Descriptor/Qualifier:
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Adaptor Proteins, Signal Transducing
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genetics* Aged Colorectal Neoplasms, Hereditary Nonpolyposis / genetics* DNA Methylation / genetics*, physiology Female Genetic Predisposition to Disease Genetic Testing / methods Germ-Line Mutation / genetics* Humans Male MutS Homolog 2 Protein / genetics Mutation Nuclear Proteins / genetics* Proto-Oncogene Proteins B-raf / genetics*, physiology |
| Chemical | |
Reg. No./Substance:
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0/Adaptor Proteins, Signal Transducing; 0/MLH1 protein, human; 0/Nuclear Proteins; EC 2.7.1.37/BRAF protein, human; EC 2.7.11.1/Proto-Oncogene Proteins B-raf; EC 3.6.1.3/MutS Homolog 2 Protein |
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