title: BRAF mutation in sporadic colorectal cancer and Lynch syndrome.
abstract: The aim of the study was to detect mutations of BRAF oncogene in colorectal cancer and to use this information to identify Lynch syndrome patients. Consecutive cases of primary colorectal cancer (n = 137) were analyzed for MLH1 protein expression using immunohistochemistry (IHC). BRAF V600E mutation was detected by IHC using a specific monoclonal antibody (VE1) and by qPCR. All MLH1 protein-negative cases were subjected to microsatellite instability analysis and MLH1 promoter methylation assay. MLH1 protein expression deficiency and high microsatellite instability (MSI-H) were detected in 18 of the 137 (13.1%) consecutive colorectal cancer specimens. Detection of the BRAF V600E mutation by IHC was 100% sensitive and specific as compared to qPCR, and this mutation was frequently present in the MSI-H group (77.8%; 14/18) and less frequently in the microsatellite-stable group (7.6%; 9/118). All BRAF V600E mutated cases of the MSI-H group presented with a MLH1 promoter methylation (14/14) as detected by methylation-specific multiplex ligation-dependent probe amplification. When BRAF was wild type in the MSI-H group, only one MLH1 promoter methylation was detected (1/4), and of the remaining three cases without MLH1 methylation, two were identified to harbor an MLH1 mutation consistent with Lynch syndrome. Finally, 11 previously confirmed Lynch syndrome cases were analyzed for BRAF V600E mutation, and all of them were wild type. In conclusion, detection of BRAF V600E in colorectal cancer specimens by IHC is sensitive and specific and may help to identify Lynch syndrome patients.
authors: Division of Pathology and Genetics, HUSLAB, and Haartman Institute, Helsinki University Central Hospital and University of Helsinki, P.O. Box 400, Helsinki, FIN-00029 HUS, Finland.
authors: Alexandra
authors: A
authors: Thiel
authors: Mira
authors: M
authors: Heinonen
authors: Jonas
authors: J
authors: Kantonen
authors: Annette
authors: A
authors: Gylling
authors: Laura
authors: L
authors: Lahtinen
authors: Mari
authors: M
authors: Korhonen
authors: Soili
authors: S
authors: Kytölä
authors: Jukka-Pekka
authors: JP
authors: Mecklin
authors: Arto
authors: A
authors: Orpana
authors: Päivi
authors: P
authors: Peltomäki
authors: Ari
authors: A
authors: Ristimäki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing / Q000379:methods; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D055815:Young Adult
chemical_list: C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
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