Association of colonic and endometrial carcinomas in Portuguese families with hereditary nonpolyposis colorectal carcinoma significantly increases the probability of detecting a pathogenic mutation in mismatch repair genes, primarily the MSH2 gene.

Hereditary nonpolyposis colorectal carcinoma (HNPCC) significantly raises the risk of developing colorectal carcinoma (CRC) and other extracolonic tumors. It is defined by the Amsterdam Criteria and is associated with germline mutations in mismatch repair genes, primarily MLH1 and MSH2. The objectives of the current study were to evaluate the presence of CRC (Type I) and other extracolonic tumors (Type II) in families with HNPCC and to analyze the findings for correlations with germline mutations in the MLH1 and MSH2 genes. Seventy families with an HNPCC diagnosis were analyzed. Denaturing gradient gel electrophoresis and direct sequencing were used for germline mutation analysis in the MLH1 and MSH2 genes. Forty-three of 70 families (61%) presented with HNPCC Type II. In 21 of 30 families that had a complete genetic diagnosis, 16 pathogenic germline mutations (7 MLH1 mutations and 9 MSH2 mutations) and 5 mutations of unknown pathogenecity (all MLH1 mutations) were found. In the remaining nine families, no mutations were detected. Unequivocally pathogenic mutations were far more common in families with HNPCC Type II compared with families that had CRC only (P = 0.01). Families with endometrial carcinoma presented with the greatest probability of mutational detection (P = 0.005). MLH1 was only gene affected in families with HNPCC Type I, whereas mutations in both MLH1 and MSH2 were found in families with HNPCC Type II (P = 0.04). However, the MSH2 gene was more frequently involved in families with HNPCC in which endometrial carcinoma was present (P = 0.005). CRC and endometrial carcinoma were associated with a greater probability of detecting pathogenic mutations in mismatch repair genes, with MSH2 involvement predominating. The results support specific mutational screening strategies, based on observed phenotypes, for families with HNPCC.

Lage PA ，Albuquerque C ，Sousa RG ，Cravo ML ，Salazar M ，Francisco I ，Maia L ，Claro I ，Suspiro A ，Rodrigues P ，Raposo H ，Fidalgo PA ，Nobre-Leitão C ... -  《CANCER》

Clinical findings with implications for genetic testing in families with clustering of colorectal cancer.

Wijnen JT ，Vasen HF ，Khan PM ，Zwinderman AH ，van der Klift H ，Mulder A ，Tops C ，Møller P ，Fodde R ... -  《NEW ENGLAND JOURNAL OF MEDICINE》

[The first molecular analysis of a Hungarian HNPCC family: a novel MSH2 germline mutation].

Czakó L ，Tiszlavicz L ，Takács R ，Baradnay G ，Lonovics J ，Cserni G ，Závodná K ，Bartosova Z ... -  《ORVOSI HETILAP》

Lower incidence of colorectal cancer and later age of disease onset in 27 families with pathogenic MSH6 germline mutations compared with families with MLH1 or MSH2 mutations: the German Hereditary Nonpolyposis Colorectal Cancer Consortium.

Plaschke J ，Engel C ，Krüger S ，Holinski-Feder E ，Pagenstecher C ，Mangold E ，Moeslein G ，Schulmann K ，Gebert J ，von Knebel Doeberitz M ，Rüschoff J ，Loeffler M ，Schackert HK ... -  《JOURNAL OF CLINICAL ONCOLOGY》

Extended microsatellite analysis in microsatellite stable, MSH2 and MLH1 mutation-negative HNPCC patients: genetic reclassification and correlation with clinical features.

Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant disorder predisposing to predominantly colorectal cancer (CRC) and endometrial cancer frequently due to germline mutations in DNA mismatch repair (MMR) genes, mainly MLH1, MSH2 and also MSH6 in families seen to demonstrate an excess of endometrial cancer. As a consequence, tumors in HNPCC reveal alterations in the length of simple repetitive genomic sequences like poly-A, poly-T, CA or GT repeats (microsatellites) in at least 90% of the cases. The study cohort consisted of 25 HNPCC index patients (19 Amsterdam positive, 6 Bethesda positive) who revealed a microsatellite stable (MSS)--or low instable (MSI-L)--tumor phenotype with negative mutation analysis for the MMR genes MLH1 and MSH2. An extended marker panel (BAT40, D10S197, D13S153, D18S58, MYCL1) was analyzed for the tumors of these patients with regard to three aspects. First, to reconfirm the MSI-L phenotype found by the standard panel; second, to find minor MSIs which might point towards an MSH6 mutation, and third, to reconfirm the MSS status of hereditary tumors. The reconfirmation of the MSS status of tumors not caused by mutations in the MMR genes should allow one to define another entity of hereditary CRC. Their clinical features were compared with those of 150 patients with sporadic CRCs. In this way, 17 MSS and 8 MSI-L tumors were reclassified as 5 MSS, 18 MSI-L and even 2 MSI-H (high instability) tumors, the last being seen to demonstrate at least 4 instable markers out of 10. Among all family members, 87 malignancies were documented. The mean age of onset for CRCs was the lowest in the MSI-H-phenotyped patients with 40.5 +/- 4.9 years (vs. 47.0 +/- 14.6 and 49.8 +/- 11.9 years in MSI-L- and MSS-phenotyped patients, respectively). The percentage of CRC was the highest in families with MSS-phenotyped tumors (88%), followed by MSI-L-phenotyped (78%) and then by MSI-H-phenotyped (67%) tumors. MSS tumors were preferentially localized in the distal colon supposing a similar biologic behavior like sporadic CRC. MSH6 mutation analysis for the MSI-L and MSI-H patients revealed one truncating mutation for a patient initially with an MSS tumor, which was reclassified as MSI-L by analyzing the extended marker panel. Extended microsatellite analysis serves to evaluate the sensitivity of the reference panel for HNPCC detection and permits phenotype confirmation or upgrading. Additionally, it confirms the MSS status of hereditary CRCs not caused by the common mutations in the MMR genes and provides hints to another entity of hereditary CRC.

Schiemann U ，Müller-Koch Y ，Gross M ，Daum J ，Lohse P ，Baretton G ，Muders M ，Mussack T ，Kopp R ，Holinski-Feder E ... -  《DIGESTION》