OBJECTIVETo analyze the somatic mutations in the D-loop of mtDNA and further evaluate the possibility of mitochondrial genetic instability in thyroid papillary carcinoma.

METHODSHypervariable regions ( HVR-I and HVR-II) in the D-loop of mtDNA from the specimen of 35 thyroid papillary cancers and matched lymphocytes were amplified by PCR, and then were sequenced.

RESULTSComparing the sequences of tumors to those of matched lymphocytes and normal thyroid tissues, 5 somatic mutations in 2 patients (5.7%) were found. Two mutations were insertions of C in a poly-cytidine (nt303) microsatellite, and 3 at positions 73, 152 and 194 in HVR-II. In addition, of the 294 genetic variants detected, 292 were previously recorded polymorphisms, whereas 2 were new polymorphisms (nt324:C-->G, nt16092:T-->A).

CONCLUSIONSMutations in the D-loop of mtDNA were found in thyroid papillary cancers, this mutation rate was lower than the reported rate of alteration in tumors of epithelial origin, and further work is required to elucidate the relationship between this mutations and the development of thyroid papillary carcinoma.