Abstract: Objective: To investigate the distribution of single nucleotide polymorphism (SNPs)of selenoprotein P(Sepp1)rs7579 site in the patients with papillary thyriod carcinoma(PTC) and the healthy controls and the interaction with non-genetic factors in the Inner Mongolia region,and to clarify the correlation of Sepp1 and the risk of PTC. Methods: The genotypic and allelic frequencies of Sepp1 from 138 patients with PTC and 140 healthy controls in the Inner Mongolia region were determined by allele-specific polymerase chain reaction(AS-PCR).Stratification analysis was conducted according to the different clinical characteristics(age,gender,tumor size and presence or absence of lymph node metastasis),and the association between the Sepp1 gene polymorphism with PTC incidence risk was analyzed in combination with non-genetic factors such as smoking,drinking,body mass index(BMI),iodized salt intake and mental state etc by multiple Logistic regression analysis.Pearson correlation analysis was used to analyze the correlations between the expression levels of c-fos and PV proteins in hipocampus tissue of the offspring rats and the learning ability indexes,the NO content,and the NOS activity in hipocampus tissue. Results: High BMI,iodized salt intake,bad mental state and big working pressure increased the risk of PTC.The differences in the frequencies of GG,GA,AA genotypes and G,A alleles of Sepp1 (rs7579) between the PTC patients and the healthy controls were not significant(χ²=0.622,P>0.05;χ²=0.673,P>0.05).But the stratification analysis results showed that there were significant differences in the genotypic frequencies of GG,GA and AA between the PTC patients and the controls in ≥ 50 years old group(χ²=7.717,P=0.028),and the frequency of AA genotype of the PTC patients was significantly lower than that of the controls(P<0.05).The relative risk of PTC incidence in the subjects with allele A (AA or GA) was lower than those with genotype GG (OR=0.481,95%CI:0.267-0.866). Conclusion: BMI, iodized salt intake,mental state and working pressure are the main influencing factors of PTC;allele A may be the protective factor of PTC.

Key words: selenoprotein P, single nucleotide polymorphism, papillary thyriod carcinoma, allele-specific polymerase chain reaction