RET/PTC rearrangements were detected by standard-sensitivity RT-PCR in 14 tumors.     ///    Prevalence of RET/PTC rearrangements in thyroid papillary carcinomas: effects of the detection methods and genetic heterogeneity.     ///    Our data suggest that broad variability in the reported prevalence of RET/PTC rearrangement is at least in part a result of the use of different detection methods and tumor genetic heterogeneity..     ///     RET/PTC rearrangements have been reported in papillary thyroid carcinomas with variable frequency in studies that used different detection methods.     ///    Prevalence of RET/PTC rearrangements in thyroid papillary carcinomas: effects of the detection methods and genetic heterogeneity..     ///    Twelve (18%) tumors had nonclonal RET/PTC that were detected only by high-sensitivity RT-PCR.     ///    Our objective was to determine the role of different detection methods and tumor genetic heterogeneity on RET/PTC detection.     ///    "High-sensitivity RT-PCR detected RET/PTC in all of these and in 12 additional cases, where the levels of expression corresponded to one to five positive cells. "    ///    "No other mutations were found in tumors harboring clonal RET/PTC, whereas 60% of tumors with subclonal and 42% of tumors with nonclonal RET/PTC harbored additional mutations. "    ///    Real-time LightCycler RT-PCR detected RET/PTC in 12 and Southern blot analysis in 11 tumors.     ///    "Sixty-five papillary carcinomas were analyzed for RET/PTC1 and RET/PTC3 using five detection methods: standard-sensitivity RT-PCR, high-sensitivity RT-PCR, real-time LightCycler RT-PCR, Southern blot analysis, and fluorescence in situ hybridization. "