Absence of PMS2 mutations in colon-CFR participants whose colorectal cancers demonstrate unexplained loss of MLH1 expression

摘要

Lynch syndrome (LS) (MIM# 120435) is a cancer predisposition condition resulting from mutations within the DNA mismatch repair (MMR) genes (MLH1, MSH2, MSH6 or PMS2). In a suspected LS family, tumors are assessed for microsatellite instability (MSI) and/or immunohistochemical (IHC) absence of MMR proteins, both of which are hallmarks of LS. To enable appropriate diagnosis, counseling and surveillance, the gene indicated by the IHC profile is screened for mutations via techniques such as denaturing high pressure liquid chromatography (DHPLC), sequencing and multiplex ligation-dependent probe amplification (MLPA). Using these approaches, mutations are identified in the majority of cases suspected of LS; however, there remains a substantial proportion of families for which mutations cannot be identified.