[Li-Fraumeni syndrome and germ-line mutations of the p53 gene].

The eponym Li-Fraumeni syndrome is given to a particular form of cancer-prone family in which the main encountered tumors are sarcomas occurring in childhood and breast cancers affecting young adult females. There is also an increased frequency of cerebral tumors, leukemias and adrenal carcinomas among these families. The transmission of the cancer-proneness is autosomal dominant and related to the loss of function of the p53 tumor suppressor gene located on the short arm of the chromosome 17. The related p53 protein is identified but its precise mechanism of action and its regulation are still unclear. It seems to activate the genes which negatively regulate the multiplication of the cell and to act as a factor of transcription. A germline mutation of the p53 gene must be looked for in every cancer-prone family but also in case of multifocal tumors, particularly osteosarcomas and glioblastomas, and in case of second malignant neoplasm. This is of major scientific as well clinical interest. Indeed, the study of new families will help to better understand the molecular mechanisms underlying the syndrome. For the family itself this allow to identify the cancer prone members and to offer them preventive measures and early detection of cancers, particularly early breast cancer detection.