[Genetic consultation: hereditary cancer risk?].

Cancer is a genetic disease of cells linked to the accumulation of mutations in genes mainly involved in cell cycle, apoptosis, and in DNA damage repair. In most patients, these mutations are acquired (somatic) during life; in some others, some mutations may be germline, inherited from one parent and transmissible to the offspring. The latter are more prone to cancer. Family cancer genetic clinics, developed since the early nineties, aim to understand the origin of a family history through the first analysis of an index case and to provide adapted counselling regarding the management of index cases and his relatives (genetic test targeted on a mutation identified in the index case). The two most frequent cancer predispositions are presented: breast-ovary syndrome linked to BRCA1 and BRCA2 mutations and Lynch syndrome linked to mutations in the DNA mismatch repair genes and associated with high risks of colorectal and endometrial cancers.