In FAP, a positive correlation was observed between the type of mutation and the penetrance of the mutated genes, estimated according to the number of polyps present in the colorectum: thus, mutations in the codons 1250–1464 are associated with the highest number of polyps, while mutations in the 5′ and 3′ regions are associated with a mild phenotype (with <100 adenomatous polyps); these two phenotypes are known as classic FAP and attenuated FAP (AFAP) [51]. The gene discussed is FAP; the disease is Familial adenomatous polyposis.