Association of vitamin D receptor gene polymorphisms with rheumatoid arthritis

Introduction: Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease of unknown etiology which causes progressive deterioration of the joints, leading to severe pain and functional disability. Vitamin D and its receptor (VDR) play a significant part in the onset of autoimmune diseases such as RA. The purpose of this study was to evaluate the association between VDR gene polymorphisms and risk of developing RA.

Material and methods: A retrospective study was performed, including 214 RA cases and 748 controls of Caucasian origin. FokI (rs2228570), BsmI (rs1544410), TaqI (rs731236), ApaI (rs7975232) and Cdx2 (rs11568820) gene polymorphisms were analyzed by TaqMan.

Results: The recessive logistic regression model showed that the VDR FokI-AA genotype was associated with lower risk of RA (p = 0.0255; OR = 0.58; 95% CI: 0.35-0.92). No other genetic polymorphism showed any association with RA in any of the models tested. Haplotype analysis revealed that the haplotypes ACGAG (p = 0.033; OR = 1.62; 95% CI: 1.04-2.53) and GTGCA (p < 0.01; OR = 2.77; 95% CI: 1.53-4.98) for BsmI, Cdx2, FokI, ApaI and TaqI were associated with higher risk of RA.

Conclusions: VDR FokI gene polymorphism showed a trend for risk of RA, taking into account the variables of gender, age and tobacco use, and preventing false positives. Among our patients we found no influence of VDR BsmI, TaqI, ApaI and Cdx2 on the risk of developing RA. However, haplotype analysis indicated that the haplotypes ACGAG and GTGCA were associated with higher risk of RA.