DNA mismatch repair genes have been found to be associated with hereditary nonpolyposis colorectal cancer (HNPCC). Inherited mutations in the MSH2 were demonstrated at high frequency in HNPCC and were shown to be associated with microsatellite instability. The demonstration that 10 to 45% of pancreatic, gastric, breast, ovarian and small cell lung cancers also display microsatellite instability s
