Molecular genetic analysis of a patient with hereditary nonpolyposis colorectal cancer syndrome

Hereditary nonpolyposis colorectal cancer types I and II constitute approximately 5% to 10% of the cases of colorectal cancer annually. Recognition of its clinical features and identification of affected families are imperative for appropriate medical and surgical management. Furthermore, molecular analysis can be performed in such families because the DNA mismatch repair genes have been identified as being mutated, thereby leading to microsatellite instability. We describe a 33-year-old woman with ovarian, uterine, and colorectal cancer, whose family, on close examination, had features consistent with hereditary nonpolyposis colorectal cancer. The patient had evidence of microsatellite instability in her colon cancer.