APC and Familial adenomatous polyposis: The severity of the disease is associated with the mutation site in the APC gene: mutations located between codons 1250 and 1464 have been associated with more severe forms of FAP, whereas mutations at the end of the gene or in exon nine are associated with a mild polyposis phenotype called attenuated familial adenomatous polyposis (AFAP) [15,30,92].