The author found that genetic predisposition to high iron status was causally associated with lower odds of RA (IVW: OR (95%CI) = 0.79 (0.65–0.94), P = 0.010; 0.59 (0.40–0.86), P = 0.007; 0.84 (0.75–0.94), P = 0.003 and 1.28 (1.06–1.55), P = 0.012 per one standard deviation increment of serum iron, ferritin, transferrin saturation, and transferrin levels, respectively). This evidence concerns the gene TF and rheumatoid arthritis.