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Multiplex SNaPshot genotyping for detecting loss of heterozygosity in the mismatch-repair genes MLH1 and MSH2 in microsatellite-unstable tumors


Bujalkova, M; Zavodna, K; Krivulcik, T; Ilencikova, D; Wolf, B; Kovac, M; Karner-Hanusch, J; Heinimann, K; Marra, G; Jiricny, J; Bartosova, Z (2008). Multiplex SNaPshot genotyping for detecting loss of heterozygosity in the mismatch-repair genes MLH1 and MSH2 in microsatellite-unstable tumors. Clinical Chemistry, 54:1844-1854.

Abstract

BACKGROUND: In the workup of patients with suspected hereditary nonpolyposis colorectal cancer (HNPCC), detection of loss of heterozygosity (LOH) could help pinpoint the DNA in the mismatch-repair (MMR) gene carrying the germline mutation, but analysis of microsatellite markers has proved unreliable for this purpose. We developed a simple, low-cost method based on single-nucleotide polymorphism (SNP) genotyping and capillary electrophoresis for the assessment of LOH at 2 MMR loci simultaneously. METHODS: We used the Applied Biosystems SNaPshot(R) Multiplex Kit with meticulously selected primers to assess 14 common SNPs in MLH1 [mutL homolog 1, colon cancer, nonpolyposis type 2 (E. coli)] and MSH2 [mutS homolog 2, colon cancer, nonpolyposis type 1 (E. coli)] and optimized the protocol for DNA isolated from peripheral blood and fresh/frozen or archival microsatellite-unstable tumors from patients with confirmed (n = 42) or suspected (n = 25) HNPCC. The 42 tumors from patients with confirmed MLH1 or MSH2 germline mutations were used to validate the method's diagnostic accuracy against results obtained with DNA sequencing or multiplex ligation-dependent probe amplification. RESULTS: The SNaPshot assay provided better detection of certain SNPs than DNA sequencing. The MLH1 and MSH2 SNP marker sets were informative in 82% and 76% of the 67 cases analyzed, respectively. The new assay displayed 100% specificity for detecting LOH and predicted the location of the germline mutation in 40% of the cases (54% of those involving MLH1, 22% in MSH2). CONCLUSIONS: Our SNP-based method for detecting LOH in MLH1 and MSH2 is simple to perform with instruments available in most clinical genetics laboratories. It can be a valuable addition to protocols now used to guide mutational screening of patients with suspected HNPCC.

BACKGROUND: In the workup of patients with suspected hereditary nonpolyposis colorectal cancer (HNPCC), detection of loss of heterozygosity (LOH) could help pinpoint the DNA in the mismatch-repair (MMR) gene carrying the germline mutation, but analysis of microsatellite markers has proved unreliable for this purpose. We developed a simple, low-cost method based on single-nucleotide polymorphism (SNP) genotyping and capillary electrophoresis for the assessment of LOH at 2 MMR loci simultaneously. METHODS: We used the Applied Biosystems SNaPshot(R) Multiplex Kit with meticulously selected primers to assess 14 common SNPs in MLH1 [mutL homolog 1, colon cancer, nonpolyposis type 2 (E. coli)] and MSH2 [mutS homolog 2, colon cancer, nonpolyposis type 1 (E. coli)] and optimized the protocol for DNA isolated from peripheral blood and fresh/frozen or archival microsatellite-unstable tumors from patients with confirmed (n = 42) or suspected (n = 25) HNPCC. The 42 tumors from patients with confirmed MLH1 or MSH2 germline mutations were used to validate the method's diagnostic accuracy against results obtained with DNA sequencing or multiplex ligation-dependent probe amplification. RESULTS: The SNaPshot assay provided better detection of certain SNPs than DNA sequencing. The MLH1 and MSH2 SNP marker sets were informative in 82% and 76% of the 67 cases analyzed, respectively. The new assay displayed 100% specificity for detecting LOH and predicted the location of the germline mutation in 40% of the cases (54% of those involving MLH1, 22% in MSH2). CONCLUSIONS: Our SNP-based method for detecting LOH in MLH1 and MSH2 is simple to perform with instruments available in most clinical genetics laboratories. It can be a valuable addition to protocols now used to guide mutational screening of patients with suspected HNPCC.

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12 citations in Web of Science®
13 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Molecular Cancer Research
07 Faculty of Science > Institute of Molecular Cancer Research
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Date:2008
Deposited On:03 Nov 2008 10:59
Last Modified:05 Apr 2016 12:32
Publisher:American Association for Clinical Chemistry
ISSN:0009-9147
Publisher DOI:10.1373/clinchem.2008.108902
PubMed ID:18772310
Permanent URL: http://doi.org/10.5167/uzh-4838

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