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Colorectal carcinoma (CRC) is one of the most prevalent malignancies in the Czech Republic. In general, there are two molecular pathways leading to CRC: one is characterized by chromosomal instability, the other by the deficiency in DNA mismatch repair (MMR) genes. MutL homologue 1 (MLH1) gene, a member of the MMR gene-family, represents a key component of the MMR system, responsible for recognition of nucleotide mismatches occurring during DNA replication, and for the recruitment of repair proteins to correct the replication errors. According to literature, somatic mutations in MMR genes, and MLH1 in particular, hallmark sporadic, MMR deficient, CRC cases. We aimed at analyzing somatic events in MLH1 gene and the determination of microsatellite instability (MSI) status in 99 DNA samples from 96 patients with sporadic CRC. Mutations were screened by high resolution melting (HRM) curve analysis. Positive cases in each run were subsequently verified by automated sequencing. Mainly gene variants were found in MLH1 gene: We discovered two new variants, one in exon 2 at position c. 204 C>G, p. Ile68Met (98 C/C, 1C/G) and the other in exon 11 at position c. 973 C>T, p. Arg325Trp (98 C/C, 1 C/T). Only the latter variant c. 973 C>T was identified as somatic mutation. All other variants found in MLH1 gene... |
