[Oncogenes and thyroid tumors].

Papillary thyroid carcinomas are characterized in 70% of cases by the presence of either a RET/PTC rearrangement, or an activating point mutation of RAS or BRAF genes that induce a constitutive activation of the MAP kinase pathway. Follicular carcinomas are characterized by the presence of a RAS mutation or of a PAX8-PPARgamma rearrangement. Inactivating mutations of the p53 gene are found only in anaplastic thyroid carcinomas.