VDR and rheumatoid arthritis: Since there are no data in the literature on the involvement of this VDR polymorphism in TNF-i treatment response, unlike the other main VDR SNPs, we investigated the possible role of rs11568820 as a predictor of drug efficacy in terms of remission and low disease activity (LDA) in a cohort of Italian subjects with RA during the treatment with first-line TNF-i, in particular with Etanercept (ETN) and Adalimumab (ADA).