Prédisposition héréditaire au cancer colorectal et inactivation de la fonction de réparation des mésappariements de l'ADN

Abstract

The hereditary non-polyposis colorectal cancer (HNPCC) syndrome is an inherited condition characterized by clinical and genealogical criteria (Amsterdam criteria), caused by germline mutations in MMR genes in about 70% of cases. In this situation, tumor cells exhibit an MSI phenotype that is evidenced by genotyping of a reference panel of 5 monucleotidic sequences. Gene carriers are at high-risk of developing colorectal, endometrial, urothelial and small intestine carcinomas, and at moderate risk of ovary, stomach and biliary tract carcinomas. Genetic counseling is based on the presence of a carcinoma belonging to one of these locations, diagnosed before the age of 40, or before 60 years in case of MSI phenotype or an affected first degree relative. Identification of germline MMR gene is an important step for recommendations of subsequent surveillance and follow-up, focused on main cancer risks, i.e. colorectum and endometrium.