Classic Familial Adenomatous Polyposis (FAP)

 

Synonym: FAP1

 

Chromosome: 5q22.2

Gene: APC (adenomatous polyposis coli)

 

Inheritance: autosomal dominant

 

Features:

(1) >= 100 colorectal adenomatous polyposis prior to age 30 years in many cases (the number and age of onset vary with the specific mutation)

(2) early onset of colorectal adenocarcinoma

(3) variable expression of extracolic lesions, both in the gastrointestinal tract and outside the GI tract

 

Differential diagnosis includes:

(1) MUTYH-associated polyposis

(2) attenuated familial adenomatous polyposis (AFAP)

(3) other polyposis syndromes