Molecular basis of familial adenomatous polyposis in the southeast of Brazil: identification of six novel mutations

The goal of this study was to screen point mutations and deletions in APC and MUTYH genes in patients suspected of familial adenomatous polyposis (FAP) in a Brazilian cohort. We used high-resolution melting, Sanger direct sequencing and multiplex ligation-dependent probe association (MLPA) assays to identify point mutations, and large genomic variations within the coding regions of APC and MUTYH genes. We identified 19 causative mutations in 40 Brazilian patients from 20 different families. Four novel mutations were identified in the APC gene and two in the MUTYH gene. We also found a high intra- and inter-familial diversity regarding extracolonic manifestations, and gastric polyps were the most common manifestation found in our cohort. We believe that the FAP mutational spectrum can be population-specific and screening FAP patients in different populations can improve pre-clinical diagnosis and improve clinical conduct