Glutathione S-transferase T1 and M1 polymorphisms and risk of thyroid neoplasms

Abstract

Background: In order to test the possibility of association between GSTT1 and M1 (glutathione S-transferase) null allele variant, in which the entire gene is absent, and the risk of TCO (thyroid carcinoma with cell oxyphilia), the case-control study was carried out. Methods: Genotypes for GSTT1 and GSTM1 were determined by multiplex PCR in the DNA from 108 healthy individuals and in DNA from samples of thyroid tumors from 130 patients of the same race and origin as the control group (Caucasian, Italian). The following types of NMTC were analyzed: oxyphilic adenoma (OA), oxyphilic carcinoma (OC) papillary thyroid carcinoma with oxyphilic features (PTCof), follicular adenoma (FA), follicular carcinoma (FC), follicular variant of PTC (fvPTC) and classical PTC. Associations between prevalence of particular genotypes and the occurrence of TCO (versus controls) and other subtypes of NMTC were tested. Associations were quantified by calculating OR (odds ratio) with 95% confidence interval. StatGraphics Plus v. 5 software (Manugistics) was used for statistical analysis. Results: In this study of the association between the GSTT1 and M1 null genotype and the increased risk of TCO, the frequency of GSTT1 null genotype of 19.2% in cases and 15.7% in controls was found with an adjusted odds ratio (OR) of 1.4 (95% confidence interval (CI) 0.70-2.81), and the frequency of GSTM1 null genotype of 59% in cases with oxyphilic tumors and of 55.6% in controls (OR 1.24; 95% CI, 0.62-2.48). Conclusion: These results indicate that the GSTT1 and M1 null genotypes do not increase the risk of development of oxyphilic tumors, as well as other types of NMTC that have been included in this study.