Sporadic colorectal cancer is a multistep process involving a number of genetic and epigenetic changes (Fearon and Vogelstein, 1990; Kinzler and Vogelstein, 1996), while familial forms such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC) have been shown to be caused by mutations in the tumour suppressor adenomatous polyposis coli (APC) and mismatch repair (MMR) genes, respectively. Here, APC is linked to hereditary nonpolyposis colon cancer.