[MIM*175100] polyposis that usually begins in childhood; polyps increase in number, causing symptoms of chronic colitis; pigmented retinal lesions are frequently found; carcinoma of the colon almost invariably develops in untreated cases; autosomal dominant inheritance, caused by mutation in the adenomatous polyposis coli gene (APC) on 5q. In Gardner syndrome, which is allelic to FAP, there are extracolonic changes (desmoid tumors, osteomas, jaw cysts). SYN: adenomatous polyposis coli, familial polyposis coli, multiple intestinal polyposis (1).