Hereditary nonpolyposis colorectal cancer (HNPCC) is frequently associated with inherited mutation in one of four DNA mismatch repair genes. Somatic mutations in the same genes are also found in a subset of sporadic colorectal cancers. A defect in DNA mismatch repair results in an RER (replication e
Mutations in MLH1 are more frequent than in MSH2 in sporadic colorectal cancers with microsatellite instability
β Scribed by Klaus K.-F. Herfarth; Ira J. Kodner; Alison J. Whelan; Jennifer L. Ivanovich; John R. Bracamontes; Samuel A. Wells Jr.; Paul J. Goodfellow
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 158 KB
- Volume
- 18
- Category
- Article
- ISSN
- 1045-2257
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β¦ Synopsis
The microsatellite instability that is a feature of tumors in patients with hereditary nonpolyposis colorectal cancer (HNPCC) is a consequence of defective DNA mismatch repair. Mutations in the DNA mismatch repair genes MSH2 and MLH1 may account for up to 90% of HNPCC kindreds. Microsatellite instability is also seen in 10-16% of sporadic colorectal cancers. A limited number of MSH2 and MLH1 mutations have been described for sporadic colorectal cancers. In this study, we screened 12 primary sporadic colorectal cancers with microsatellite instability for mutations in MSH2 and MLH1 by using reverse transcription-polymerase chain reaction (RT-PCR) and single-strand-conformation-variant (SSCV) analysis. Eight mutations were identified in six tumors. One mutation in MLH1 was found to be present in the patient's germline DNA. Four tumors had somatic mutations in MLH1, and, in two of these tumors, two different mutations were identified. A single tumor had a somatic MSH2 mutation. Our observations suggest that MLH1 is mutated more frequently than MSH2 in sporadic colorectal cancers with microsatellite instability.
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Mismatch repair genes MSH2 and MLH1 are considered to be the two major genes that are responsible for hereditary nonpolyposis colorectal cancer (HNPCC). Germline heterozygous inactivating mutations of MSH2 and MLH1 have been identified previously in a substantial fraction of individuals who are pred
## Genetic diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC ) may have a significant impact on the clinical management of patients and their at-risk relatives. At present, clinical criteria represent the simplest and most useful method for the identification of HNPCC families and for
Replication errors (RER) are frequently seen in both sporadic and hereditary forms of colorectal cancer. In hereditary nonpolyposis colorectal cancer (HNPCC), RER is associated with defects in DNA mismatch repair genes. Two of these genes, MSH2 and MLH1, account for a major share of this cancer synd