APC and Familial adenomatous polyposis: In order to verify whether the genotype of APC gene may be a potential risk factor for the development of extracolonic manifestations in FAP patients, we first studied the association between genotype and phenotype among FAP patients obtained from the Hereditary Gastrointestinal Cancer Registry (High Risk cancer Clinics, Huntsman Cancer Institute, University of Utah), which includes 457 participants with diagnoses of FAP (Supplementary Table S1).