Correlation of Polymorphisms of Natural Resistance-Associated Macrophage Protein 1 (NRAMP1) Gene and Smoking with the Risk of Rheumatoid Arthritis in Chinese Han People.

BACKGROUND In this study we report on the possible connection between single nucleotide polymorphisms (SNPs) in natural resistance-associated macrophage protein 1 (NRAMP1) gene and the risk of rheumatoid arthritis (RA) in the Chinese Han population. MATERIAL AND METHODS A total of 248 participants consisting of 116 RA cases and 132 healthy individuals were recruited for the current study. Genotyping for NRAMP1 gene polymorphisms was implemented using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The chi-square test was used to detect discrepancies in genotype and allele frequencies between the RA case group and the control group. Odds ratios (ORs) with 95% confidence intervals (CIs) was used to evaluate relative risk of RA. The results were adjusted by logistic regression analysis. RESULTS The TT genotype and T allele in rs17221959 showed dramatically different distribution between RA cases and healthy controls. After adjustment, TT genotype (OR=0.338, 95%CI=0.278-1.214, P=0.028) and T allele (OR=0.608, 95%CI=0.298-0.956, P=0.005) showed close association with reduced risk of RA. For rs1059823, no obvious diversity was uncovered in either genotype or allele distribution between the 2 groups. Interaction analysis showed that smoking decreased the protective function of TT in rs17221959. CONCLUSIONS This study suggested that the TT genotype and T allele in rs17221959 decreased RA risk. Smoking could decrease the protective effect of TT.