What is attenuated familial adenomatous polyposis (AFAP)?
Attenuated familial adenomatous polyposis (AFAP) is a milder form of FAP that, like classic FAP, is due to mutations in the APC gene. Attenuated FAP differs from the classical form of FAP in the number of colonic adenomas (polyps that are at a precancerous stage in which they may or may not develop into cancerous cells) that develop (usually less than 100; average 30) and the average age of onset for colorectal cancers (55 for attenuated FAP as opposed to 40 for classical FAP). The attenuated form of FAP has been associated with mutations near the beginning (5-prime) or the end (3-prime) of the APC gene. Individuals are encouraged to obtain medical records documenting the number and type of colon polyps they, themselves, have and the number and type of colon their relatives have; this knowledge may help differentiate between FAP and AFAP in a family. AFAP may be associated with small, increased risks for upper gastrointestinal (duodenal, gastric fundic gland, and hepatobiliary) polyps
