title: Bias in detection of instability of the (C)8 mononucleotide repeat of MSH6 in tumours from HNPCC patients.
abstract: Recently, we and others reported instability in the (C)8 repeat in exon 5 of MSH6 as a preferential target for somatic mutations in tumours from MSH6 germline mutation carriers. Here, we report that in 45% of tumours from MLH1, MSH2 and MSH6 germline mutation carriers no sequence change in the (C)8 repeat of MSH6 was found upon DNA sequencing analysis of PCR products with a shift in electrophoresis mobility. Using "standard" PCR primers a high frequency of instability (50-86%) of the (C)8 repeat was found, but using a modified PCR reverse primer, accomplishing modulation of non-templated addition of adenine during in vitro PCR amplification by the Taq polymerase, a markedly lower frequency of instability was found in tumours from MLH1, MSH2 and MSH6 mutation carriers (6, 13 and 40%, respectively). Furthermore, a significant difference of the frequency of instability of the (C)8 repeat in tumours from MSH6 mutation carriers was found compared to MLH1, MSH2 mutation carriers. These results might have important implications for the detection of instability of other short mononucleotide repeats, e.g. TGFbetaRII, BAX, IGFRII, PTEN, BRCA2.
authors.affiliation: Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands. W.J.F.de_Leeuw@LUMC.nl
authors.forename: W J
authors.initials: WJ
authors.lastname: de Leeuw
authors.forename: M
authors.initials: M
authors.lastname: van Puijenbroek
authors.forename: R
authors.initials: R
authors.lastname: Merx
authors.forename: J T
authors.initials: JT
authors.lastname: Wijnen
authors.forename: A H
authors.initials: AH
authors.lastname: Bröcker-Vriends
authors.forename: C
authors.initials: C
authors.lastname: Tops
authors.forename: H
authors.initials: H
authors.lastname: Vasen
authors.forename: C J
authors.initials: CJ
authors.lastname: Cornelisse
authors.forename: H
authors.initials: H
authors.lastname: Morreau
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D015982:Bias; D002352:Carrier Proteins; D004252:DNA Mutational Analysis; D017931:DNA Primers / Q000378:metabolism; D004268:DNA-Binding Proteins; D005091:Exons; D005656:Fungal Proteins / Q000235:genetics*; D017353:Gene Deletion; D006801:Humans; D018895:Microsatellite Repeats; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics; D009687:Nuclear Proteins; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000235:genetics; D015203:Reproducibility of Results; D029701:Saccharomyces cerevisiae Proteins; D012680:Sensitivity and Specificity; D019680:Trinucleotide Repeat Expansion
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C501486:MLH1 protein, human; C098790:MSH6 protein, S cerevisiae; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D029701:Saccharomyces cerevisiae Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein