Novel Missense Mutation at Codon 2774 (C.8321 G>A) p.S2774N of APC Gene in a Denovo Case of Familial Adenomatous Polyposis.

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.