Identification of mismatch repair gene mutations in young patients with colorectal cancer and in patients with multiple tumours associated with hereditary non-polyposis colorectal cancer

Abstract

Background: Patients with early-onset colorectal cancer (CRC) or those with multiple tumours associated with hereditary non-polyposis colorectal cancer (HNPCC) raise suspicion of the presence of germline DNA mismatch repair (MMR) gene mutations. Aim: To analyse the value of family history, microsatellite instability (MSI) analysis and MMR protein staining in the tumour to predict the presence of an MMR gene mutation in such patients. Methods: In 281 patients diagnosed with CRC before the age of 50 years or with CRC and at least one additional HNPCC-associated cancer, germline mutation analysis in MLH1, MSH2 and MSH6 was carried out with denaturing gradient gel electrophoresis and multiplex ligation-dependent probe amplification. MSI analysis with five consensus markers and MMR protein staining for MLH1, MSH2 and MSH6 were carried out in the tumours. Results: 25 pathogenic mutations (8 in MLH1, 9 in MSH2 and 8 in MSH6) were found. MSI analysis missed three and immunohistochemistry (IHC) missed two mutation carriers. Sensitivities of family history, MSI analysis and IHC for the presence of a mutation were 76%, 82% and 88%, specificities were 64%, 70% and 84%, and positive predictive values were 19%, 23% and 38%, respectively. Multivariate analysis showed the highest odds ratio for IHC (38.3, 95% confidence interval 9.0 to 184). Prevalence of pathogenic germline MMR gene mutations in patients with CRC before the age of 50 years was 6% and in those with >2 HNPCC-associated tumours was 22%. In the second group, no mutation carriers were found among the 29 patients who were diagnosed with their first tumour after the age of 60 years. Conclusion: Family history, MSI analysis and IHC are indicative parameters to select patients with CRC for MMR gene mutation analysis. The data show that IHC is the best single selection criterion.

Molecular markers and clinical behavior of uterine carcinosarcomas: focus on the epithelial tumor component

“…21 It has been shown that loss of immunohistochemical staining of MMR proteins (MLH1, MSH2 and MSH6) correlates to the corresponding MMR gene mutation. 22 We observed that expression levels of MSH2 and MSH6 correlated between epithelial and mesenchymal tumor components. Above-mentioned results are in line with other studies and confirm the monoclonal origin of uterine carcinosarcomas.…”

Patients with an unexplained microsatellite instable tumour have a low risk of familial cancer

“…Their methods to analyse germline mutations are comparable with those used in our study. The sensitivity of germline mutation detection could not be deduced from other studies, as they did not include analysis of hypermethylation of the MLH1 promoter and/or performed less comprehensive germline mutation analyses (Mangold et al, 2005;Barnetson et al, 2006;Niessen et al, 2006). Wagner et al (2003) also found a difference in prevalence of pathogenic MLH1, MSH2, or MSH6 mutations between families that fulfilled the Amsterdam criteria (39 mutations in 49 families (80%)) and those not fulfilling these criteria (five mutations in 10 families (50%)) using methods that detect a similar type of mutations as the methods used in the present study.…”

Very low prevalence of germline MSH6 mutations in hereditary non-polyposis colorectal cancer suspected patients with colorectal cancer without microsatellite instability

“…Previous studies suggested that the sensitivity of MSI analysis to predict an MSH6 mutation is low and that MSI should not be used as a selection criterion for MSH6 mutation analysis , finding microsatellite stable or low patterns in 17% up to 50% (Berends et al, 2002;Hendriks et al, 2004;Plaschke et al, 2004;Niessen et al, 2006;Pinto et al, 2006) of HNPCC-associated tumours of MSH6 mutation carriers. However careful consideration of previous studies is required as part of the conclusions are based on MSH6 missense mutations of unknown pathogenecity or testing a sporadic tumour within an HNPCC family (a phenocopy) as suggested by positive immunostaining of MSH6 in the tumour.…”

“…British Journal of Cancer (2006) In clinical practice MSI analysis is used as a prescreening tool to select families for further analysis of MMR gene defects. Germline mutations in the MSH6 MMR gene account for approximately 15 -30% of cases of HNPCC (Hampel et al, 2005;Barnetson et al, 2006;Niessen et al, 2006). However MSH6 mutation carriers were reported to have tumours without an MSI-high pattern (Berends et al, 2002;Hendriks et al, 2004;Plaschke et al, 2004), whereas in MLH1 and MSH2 mutation carriers almost all HNPCC-associated tumours show MSI (Lynch and Lynch, 2005).…”