Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody . MutS Homologue 6 (MSH6) is a Mismatch repair (MMR) protein. Its deficiency results in microsatellite instability (MSI). Loss of nuclear expression of MSH6 only indicates high probability of Lynch syndrome (sequencing and/or large deletion/duplication testing of germline MSH6 may be indicated)