Academy of Medical Sciences of I.R. Iran Archives of Iranian Medicine 1029-2977 18 7 2015 07 01 Novel Missense Mutation at Codon 2774 (C.8321 G>A) p.S2774N of APC Gene in a Denovo Case of Familial Adenomatous Polyposis 0 0 EN Seyed Mohammad Hossein Kashfi Mina Golmohammadi Faegheh Behboudi Farahbakhsh Ehsan Nazemalhosseini Mojarad Pedram Azimzadeh Mohsen Norouzinia Mahdi Montazer Haghighi Zahra Akbari Behzad Damavand Mahsa Molaei Fakhrialsadat Anaraki Hamid Asadzadeh Aghdaei Mohammad Reza Zali Journal Article Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease caused by germline mutation in Adenomatous Polyposis Coli (APC) gene. FAP accounts less than 1% of all colorectal cancers incidence. Patients generally present hundreds to thousands of adenomas in colon and rectum and develop colorectal cancer by age 35 – 40 if left untreated. A milder form of FAP with fewer numbers of polyps (< 100) is Attenuated FAP (AFAP) and in comparison with classical FAP, it usually diagnosed at an older age. Approximately 15% – 20% of FAP patients are ‘‘de novo’’ cases without any family history of the disease and novel APC mutations account for approximately 25% of FAP cases. In our study, we reported a novel missense mutation at the APC gene in a denovo patient with AFAP like phenotype.