The profile of several inflammatory cytokines, such as IL-1, IL-6, IL-8, IL-18, and IL-29 in synovial fluids was associated with RA (Kaneko et al., 2000; Shao et al., 2009; Kokebie et al., 2011; Wang et al., 2012). Here, IFNL1 is linked to rheumatoid arthritis.