The levels of citrullinated ITIH4 were significantly higher in RF+ ACPA+ patients compared with RF− ACPA+, RF− ACPA− patients (p = 0.011, p = 0.025, respectively) (Table 4), suggesting that citrullinated ITIH4 levels were associated with RF levels in patients with RA. This evidence concerns the gene ITIH4 and rheumatoid arthritis.