MIF and rheumatoid arthritis: It has been reported that MIF expression increases with CATT repeat number (Baugh et al., 2002), and high‐expression alleles (CATT6‐8) are associated with an increased risk for RA and more severe joint erosion among RA patients; whereas the low expression allele (CATT5) has been associated with a less aggressive rheumatoid disease (Baugh et al., 2002; Radstake et al., 2005).