Novel variants of unknown significance in the gene identified in patients with hereditary colon cancer.

Lynch syndrome is associated with genetic variants in mismatch repair () genes. Pathogenic variants in the and genes occur in most families in which the phenotype is highly penetrant. These testing criteria are likely to miss individuals with Lynch syndrome due to the less penetrant genes, such as and . So far, several mutations in the gene have been described as responsible for the clinical manifestation of Lynch syndrome. Recent data have reported that families with atypical Lynch phenotype were found to have primarily monoallelic mutations in the gene. We analyzed the gene to detect mutations in members of 64 Lynch syndrome families by direct sequencing. We report the identification of several genetic variants in patients with LS, of which three are novel variants. The carriers of these novel variants were also carried of other variants in gene and/or in other genes. Therefore, we think that these novel variants may act in additive manner to manifestation LS phenotype.