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Updated: Jun 11, 2026
Wild-type Blocking PCR Combined with Direct Sequencing as a Highly Sensitive Method for Detection of Low-Frequency Somatic Mutations
Published on: March 29, 2017
Current clinical criteria for Lynch syndrome are not sensitive enough to identify MSH6 mutation carriers
Wenche Sjursen1, Bjørn Ivar Haukanes, Eli Marie Grindedal
1Department of Pathology and Medical Genetics, St Olavs University Hospital, Trondheim, Norway. wenche.sjursen@stolav.no
Background:
Reported prevalence, penetrance and expression of deleterious mutations in the mismatch repair (MMR) genes, MLH1, MSH2, MSH6 and PMS2, may reflect differences in the clinical criteria used to select families for DNA testing. The authors have previously reported that clinical criteria are not sensitive enough to identify MMR mutation carriers among incident colorectal cancer cases.
Objective:
To describe the sensitivity of the criteria when applied to families with a demonstrated MMR mutation.
Methods:
Families with an aggregation of colorectal cancers were examined for deleterious MMR mutations according to the Mallorca guidelines. All families with a detected MMR mutation as of November 2009 were reclassified according to the Amsterdam and Bethesda criteria.
Results:
Sixty-nine different DNA variants were identified in a total of 129 families. The original Amsterdam clinical criteria were met by 38%, 12%, 78% and 25% of families with mutations in MSH2, MSH6, MLH1 and PMS2, respectively. Corresponding numbers for the revised Amsterdam criteria were 62%, 48%, 87% and 38%. Similarly, each of the four clinical Bethesda criteria had low sensitivity for identifying MSH6 or PMS2 mutations.
Conclusion:
Amsterdam criteria and each of the Bethesda criteria were inadequate for identifying MSH6 mutation-carrying kindreds. MSH6 mutations may be more common than currently assumed, and the penetrance/expression of MSH6 mutations, as derived from families meeting current clinical criteria, may be misleading. To increase detection rate of MMR mutation carriers, all cancers in the Lynch syndrome tumour spectrum should be subjected to immunohistochemical analysis and/or analysis for microsatellite instability.
Insights
Clinical criteria for Lynch syndrome are inadequate for identifying mismatch repair (MMR) gene mutations, particularly MSH6. Improved detection requires broader screening of MMR gene mutations in colorectal cancer families.
Area of Science:
- Genetics
- Oncology
- Clinical Diagnostics
Background:
- Prevalence, penetrance, and expression of mismatch repair (MMR) gene mutations (MLH1, MSH2, MSH6, PMS2) may be influenced by clinical selection criteria for genetic testing.
- Previous research indicated that current clinical criteria lack sensitivity in identifying MMR mutation carriers among colorectal cancer patients.
Purpose of the Study:
- To evaluate the sensitivity of established clinical criteria in identifying families with confirmed MMR gene mutations.
- To assess the adequacy of Amsterdam and Bethesda criteria for detecting specific MMR gene mutations, including MSH6 and PMS2.
Main Methods:
- Families with aggregated colorectal cancer cases were assessed for MMR gene mutations using Mallorca guidelines.
- Detected MMR mutation-positive families (as of November 2009) were re-evaluated against Amsterdam and Bethesda criteria.
Main Results:
- Sixty-nine distinct DNA variants were found across 129 families.
- Original Amsterdam criteria identified only 12% of MSH6 mutation-carrying families.
- Revised Amsterdam and Bethesda criteria demonstrated low sensitivity for MSH6 and PMS2 mutations.
Conclusions:
- Amsterdam and Bethesda criteria are insufficient for identifying MSH6 mutation carriers.
- MSH6 mutations might be more prevalent than currently recognized, and their penetrance may be underestimated.
- Enhanced detection of MMR mutation carriers necessitates immunohistochemical or microsatellite instability analysis for all Lynch syndrome-associated cancers.
