In this study, we generated mice characterized by thyrocyte-specific expression of the RET/PTC1 oncogene in conjunction with one or two null alleles of Patz1. The absence or even the reduction of Patz1 expression enhanced RET/PTC1-induced thyroid carcinogenesis, promoting the rapid development of aggressive carcinomas, including ATC and solid variant of PTC. This evidence concerns the gene RET and thyroiditis.