Evaluation of the PAX8/PPARG translocation in follicular thyroid cancer with a 4-color reverse-transcription PCR assay and automated high-resolution fragment analysis.
BACKGROUND
Molecular testing of thyroid malignancies, in combination with cytologic and histologic examination, is becoming increasingly attractive as a tool for refining traditional morphologic diagnosis. The molecular changes associated with follicular thyroid carcinoma (FTC) are point mutations in RAS oncogenes or the presence of PAX8/PPARG (paired box 8/peroxisome proliferator-activated receptor gamma) rearrangement.


METHODS
We developed and validated a clinical assay for the detection of PAX8/PPARG rearrangements that uses a 4-color reverse-transcription PCR (RT-PCR) assay and high-resolution fragment analysis.


RESULTS
The RT-PCR assay is applicable for detecting the various described fusion transcripts of PAX8/PPARG in formalin-fixed, paraffin-embedded thyroid tissue and in fine-needle aspirate biopsy washes from thyroid nodules. The analytical sensitivity of the assay is 1 abnormal cell in a background of 100-10 000 translocation-negative cells. A comparison of the RT-PCR assay with dual-fusion fluorescence in situ hybridization showed an overall concordance of 95%. With this assay, we obtained a prevalence for the PAX8/PPARG rearrangement in FTC of 62% (13 of 21 cases), compared with a 5% prevalence (3 of 55) for other follicular cell-derived neoplasms.


CONCLUSIONS
The introduction of this assay into clinical practice could provide useful information for the diagnosis and possibly for the prognosis and treatment of thyroid cancer in the future.
Algeciras-Schimnich
Alicia
A
Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA.
Milosevic
Dragana
D
McIver
Bryan
B
Flynn
Heather
H
Reddi
Honey V
HV
Eberhardt
Norman L
NL
Grebe
Stefan K G
SK
D018263:Adenocarcinoma, Follicular / Q000235:genetics* / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000072636:PAX8 Transcription Factor; D047495:PPAR gamma / Q000235:genetics*; D051761:Paired Box Transcription Factors / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000191:economics / Q000379:methods*; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000473:pathology
D000072636:PAX8 Transcription Factor; C083325:PAX8 protein, human; D047495:PPAR gamma; D051761:Paired Box Transcription Factors