Lifetime Colonic Polyp Rate Comparisons and the EPCAM Deletion

Background: The 2009 discovery of the EPCAM deletion led to an addition to Lynch syndrome, traditionally characterized by mutations of mismatch repair mutations (MMR) MLH1, MSH2, MSH6 and PMS2. Patients positive for the EPCAM deletion show some of the phenotype of Lynch syndrome with the MSH2 mismatch repair mutation, but do not show a detectable mutation in MSH2. Patients with the EPCAM deletion also develop fewer extracolonic cancers than patients with MSH2 mismatch repair mutations. It was hypothesized that since EPCAM deletions are much more site-specific to the colon, there may be an increased development of colonic polyps compared to patients with other MMR mutations.