A 40-year-old woman presents with endometrial carcinoma. Her family history reveals that her mother died of endometrial cancer at age 50, while her 42-year-old brother was recently diagnosed with coloncancer. You begin to suspect a familial cancer syndrome. What gene is most likely to be mutated in this family

The answer is C. This family likely has hereditary nonpolyposis colorectal cancer (HNPCC) syndrome or Lynch syndrome. This syndrome is due to defects in DNA mismatch repair genes, with MLH1, MSH2, MSH6, and PMS2 representing the primary culprits. -WT-1 mutations predispose patients to Wilms tumors and a variety of other defects -APC is mutated in familial adenomatous polyposis (FAP) -Germline mutations in p53 are seen in Li Fraumeni syndrome -BRCA-1 mutations predispose women to breast carcinoma