ret/PTC and BRAF act as distinct molecular, time-dependant triggers in a sporadic Irish cohort of papillary thyroid carcinoma.

The purpose of this study was to assess BRAF mutation rates in various thyroid tissues and to investigate if concomitant mutations with ret/PTC activation occurred in inflammatory and neoplastic lesions. To this end, we developed a novel Taqman based screening assay for the common T1799A BRAF mutation. Heterozygous T1799A mutations were detected in 13 of 34 (44%) papillary thyroid carcinomas (PTCs) tested. No such mutations were detected in the other tissue types tested. Concomitant presence of both oncogenes was reported in 5 of the 34 PTCs. A significant temporal trend was observed, with ret/PTC chimera detected for the most part before 1997 and BRAF mutations being more prevalent after 1997. The results suggest that some environmental/etiological agent(s) may have influenced the pathobiology of thyroid tumor development, among the population examined, over time.