Molecular genetics and hereditary cancer: Hereditary nonpolyposis colorectal carcinoma as a model

Hereditary nonpolyposis colorectal carcinoma (HNPCC) is frequently associated with the germline mutation of a DNA mismatch repair gene. Tumors from these patients typically exhibit microsatellite instability, which is a reflection of their lack of mismatch repair activity. The genetic diagnosis of these individuals relies on family history, tumor analysis for evidence of lack of mismatch repair, and, finally, mutational analysis of the mismatch repair genes themselves. Early diagnosis of germline mutations in HNPCC individuals is likely to lead to improved cancer surveillance and early tumor detection.