RET/PTC Translocations and Clinico-Pathological Features in Human Papillary Thyroid Carcinoma..     ///    "Up to now, 13 different types of RET/PTC rearrangements have been reported but the two most common are RET/PTC1 and RET/PTC3. "    ///    "Recently, a diagnostic role of RET/PTC rearrangements has been proposed. "    ///    The overall prevalence of RET/PTC rearrangements varies from 20 to 70% of PTCs and they are more frequent in childhood than in adulthood thyroid cancer.     ///    "Ionizing radiations are responsible for the generation of RET/PTC rearrangements, as supported by in vitro studies and by the evidence that RET/PTC, and particularly RET/PTC3, are highly prevalent in radiation induced PTC. "    ///    "In contrast, RET/PTC1 rearrangement does not correlate with any clinical-pathological characteristics of PTC. "    ///    "The first RET rearrangement, named RET/PTC, was discovered in 1987. "    ///    Controversial data have been reported on the relationship between RET/PTC rearrangements and the PTC prognosis.     ///    "Moreover, the RET protein and mRNA expression level did not show any correlation with the outcome of patients with PTC and no correlation between RET/PTC rearrangements and the expression level of the thyroid differentiation genes was observed. "