Classic FAP: typically characterised by more than 100 colorectal polyps. Attenuated FAP (AFAP): characterised by a later age of onset and usually a much smaller number of polyps (< 100) in the colon. Despite the milder course, the lifetime risk of colon cancer is similar to that of classic FAP. Gardner syndrome is a variant of FAP. People with this syndrome have multiple adenomatous colon polyps, but also other tumours outside the gastrointestinal organs (epidermoid cysts, fibromas, desmoid tumours, osteomas). Turcot syndrome is considered a variant of FAP or Lynch syndrome. People with this syndrome have many adenomatous colon polyps, an increased risk of colorectal cancer and an increased risk of brain tumours (glioblastoma and medulloblastoma).