APC and colorectal cancer: Over 5% of colorectal cancer cases are due to a genetic predisposition, and one frequent abnormality causing predisposition to human colorectal cancer is mutation in the adenomatous polyposis coli (APC) gene.12 In humans, familial adenomatous polyposis (FAP) is characterized by the onset of multiple adenomas in the colon that can progress to tumors and metastatic forms of colorectal cancer.