BRAF Mutation Analysis in Fine Needle Aspiration (FNA) Cytology of the Thyroid

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Abstract
BRAF mutations have been detected in 30% to 80% of papillary thyroid carcinomas (PTC). Several detection methods for BRAF mutation have been reported, but a direct comparison between different assay methods has not been previously reported. In this study, we examined the diagnostic utility of BRAF (T1799A) mutation in 71 cases of thyroid fine needle aspiration specimens using 4 different methods, including direct sequencing, Colorimetric Mutector Assay, real-time LightCycler polymerase chain reaction (LC PCR) with fluorescence resonance energy transfer probes, and an allele-specific LC PCR with CYBR green 1. BRAF mutation was detected in 31 of 58 cases of PTC, but not in 13 cases of non-PTC lesions. The 4 assay methods used in this study were sensitive, reliable, and comparable with each other (100% of specificity and 53.5% of sensitivity). PTC harboring BRAF mutation had higher extrathyroidal invasion and/or lymph node metastasis than PTC with wild-type BRAF. BRAF mutation analysis should be useful for the clinical diagnosis of PTC in cases of indeterminate fine needle aspiration specimen, because of the high degree of specificity. Our results indicate that there is similar sensitivity for the four detection methods. However, the allele-specific LC PCR with CYBR green 1 method is most rapid, easier to perform, and least expensive technique, and it can be readily performed in most molecular diagnostic laboratories.