OBJECTIVETo explore the associations between the single nucleotide polymorphism of human mismatch repair gene hMLH1 and the papillary thyroid carcinoma (PTC) in Chinese Han people.

METHODSA hospital based 1:1 matched case-control study was carried out. The single nucleotide polymorphism (-93G > A, 1151T > A and 655A > G) for 204 pairs of cases with PTC as well as healthy controls was identified by PCR-RFLP, PCR-ASO and DNA sequencing.

RESULTSWith univariate analysis, we found that compared to 1151TT genotype, the TA genotype could increase the PTC risk marginally, with odds ratio (OR) of 2.15 (95%CI: 0.99 - 4.85); While the mutant genotype TA + AA could increase the PTC risk statistically significant, with OR of 2.15(95%CI: 1.02 - 4.69). With 2 x 4 cross-over study, we found that compared to -93GG and 1151TT genotypes, individuals with both -93GA + AA and 1151TA + AA could increase the PTC risk marginally, with OR of 2.50 (95%CI: 0.96 - 6.67); While, compared to 655AA and 1151TT genotypes, individuals with both 655AA and 1151TA + AA could increase the PTC risk statistically significant, with OR of 2.50 (95%CI: 1.02 - 4.73). Multivariate and conditional logistic regression analysis showed the genotype of 1151TA, the history of receiving CT diagnosis, the history of tumor, the negative life events and eating seafood frequently could increase the risk of PTC, with OR of 6.79 (95%CI: 3.18 - 14.49), 3.35 (95%CI: 1.93 - 5.80), 39.03 (95%CI: 3.70 - 41.60) and 3.98 (95%CI: 1.81 - 8.73); While, eating fruit frequently could decrease the PTC risk.

CONCLUSIONThe 1151TA + AA genotype, the history of receiving CT diagnosis, the history of tumor, the negative life events and eating seafood frequently were the risk factors of PTC, while eating fruit frequently was the protective factor.