Microsatellite instability in colorectal adenomas and hyperplastic polyps in Lynch syndrome

Background Lynch syndrome is characterized by germline mutations in DNA mismatch repair (MMR) genes and carries up to a 70% lifetime risk of colorectal cancer. Impaired MMR gene function results in an abundance of small aberrant nucleotide repeat sequences termed microsatellite instability (MSI). MSI is present in 80-85% of colorectal cancers associated with Lynch syndrome. Prior studies have demonstrated that MMR gene function (as measured by immunohistochemistry) is often lost in Lynch-associated adenomas but is preserved in hyperplastic polyps. The aim of our study was to evaluate the prevalence of MSI in adenomatous and hyperplastic polyps from individuals with Lynch Syndrome.