Multimodal Molecular Screening Is Required to Improve the Sensitivity of <i>MLH1</i> and <i>MSH2</i> Mutation Analysis
Authors: Anne Andermann, Isabelle Thiffault, Nora Wong, Philip Gordon, Elizabeth MacNamara, George Chong, William Foulkes, Antonio Percesepe, Maurizio Ponz de Leon, Päivi Peltomäki
Journal: Journal of Clinical Oncology (2002)

Article Tools SPECIAL DEPARTMENTS Article Tools OPTIONS & TOOLS Export Citation Track Citation Add To Favorites Rights & Permissions COMPANION ARTICLES No companion articles ARTICLE CITATION DOI: 10.1200/JCO.2002.20.6.1705 Journal of Clinical Oncology - published online before print September 21, 2016 PMID: 11896123 Multimodal Molecular Screening Is Required to Improve the Sensitivity of MLH1 and MSH2 Mutation Analysis Anne AndermannxAnne AndermannSearch for articles by this author , Isabelle ThiffaultxIsabelle ThiffaultSearch for articles by this author , Nora WongxNora WongSearch for articles by this author , Philip GordonxPhilip GordonSearch for articles by this author , Elizabeth MacNamaraxElizabeth MacNamaraSearch for articles by this author , George ChongxGeorge ChongSearch for articles by this author , William FoulkesxWilliam FoulkesSearch for articles by this author Antonio PercesepexAntonio PercesepeSearch for articles by this author , Maurizio Ponz de LeonxMaurizio Ponz de LeonSearch for articles by this author , Päivi PeltomäkixPäivi PeltomäkiSearch for articles by this author Show More McGill University Health Centre, Montreal, Quebec, CanadaSir M.B. Davis-Jewish General Hospital, McGill University, Montreal, Quebec, CanadaUniversity of Modena, Modena, ItalyUniversity of Helsinki, Helsinki, Finland https://doi.org/10.1200/JCO.2002.20.6.1705 First Page Full Text PDF Figures and Tables © 2002 by American Society of Clinical OncologyjcoJ Clin OncolJournal of Clinical OncologyJCO0732-183X1527-7755American Society of Clinical OncologyResponse15032002In Reply:We would like to thank Dr Andermann et al for their comments and interest in our study. It gives us the opportunity to re-emphasize the risks for underestimating the frequency of hereditary nonpolyposis colorectal cancer (HNPCC), as thoroughly discussed in our article,1 and to share the point raised that a multitechnical approach to the molecular diagnosis of HNPCC is most desirable. In fact, we, too, applied a second method, namely Southern blot hybridization, for selected cases in our study, with the aim to detect large genomic deletions that would have been missed by exon-specific sequencing or single-strand conformational polymorphism.The authors also present their personal experience in mutation screening with an RNA-based technique (in vitro synthesized protein assay) together with direct DNA sequencing and propose this combined approach as the gold standard for mutation detection in HNPCC. The authors found six cDNA deletions (four in MLH1 and two in MSH2) that would have escaped detection by direct exon-specific sequencing. Although we agree that in vitro synthesized protein assay is useful as a rapid screening method, we would like to stress the importance of validating all cDNA changes at the genomic level. Apart from genomic deletion, cDNA changes could represent alternatively spliced isoforms, as previously demonstrated for both MSH2 and MLH1,2,3 and therefore, confirmation on genomic DNA is required, for example, for a mutation to be included in the ICG-HNPCC mutation database.4Whereas technical shortcomings may result in the failure to detect some mutations, we would like to point out that a clear reduction of mutation detection rates is also seen when comparing HNPCC families not meeting the Amsterdam criteria with those that meet these criteria,5,6 suggesting that the prevalence of germline mutations in the mismatch repair genes strongly depends on the clinical presentation and method of ascertainment of the cases.1. Percesepe A, Borghi F, Menigatti M, et al: Molecular screening for hereditary nonpolyposis colorectal cancer: A prospective, population-based study. J Clin Oncol 19:: 3944,2001-3950, Link, Google Scholar2. Charbonnier F, Martin C, Scotte M, et al: Alternative splicing of messenger RNA in human normal cells. Cancer Res 55:: 1839,1995-1841, MLH1 Medline, Google Scholar3. Genuardi M, Viel A, Bonora D, et al: Characterization of and alternative splicing and its relevance to molecular testing of colorectal cancer susceptibility. Hum Genet 102:: 15,1998-20, MLH1 MSH2 Crossref, Medline, Google Scholar4. Peltomäki P, Vasen HF: Mutations predisposing to hereditary nonpolyposis colorectal cancer: Database and results of a collaborative study—The International Collaborative Group on Hereditary Nonpolyposis Colorectal Cancer. Gastroenterology 113:: 1146,1997-1158, Crossref, Medline, Google Scholar5. Nystrom-Lahti M, Wu Y, Moisio AL, et al: DNA mismatch repair gene mutations in 55 kindreds with verified or putative hereditary non-polyposis colorectal cancer. Hum Mol Genet 5:: 763,1996-769, Crossref, Medline, Google Scholar6. Wijnen J, Khan PM, Vasen H, et al: Hereditary nonpolyposis colorectal cancer families not complying with the Amsterdam criteria show extremely low frequency of mismatch-repair-gene mutations. Am J Hum Genet 61:: 329,1997-335, Crossref, Medline, Google Scholar