C1QTNF6 and rheumatoid arthritis: Notably, high CTRP1 and CTRP6 serum levels are also associated with increased TNF-α, IL-1β, and IL-6 blood concentrations [16,17,22,47,49,54,58], and CTRP1 and CTRP6 serum levels are increased in patients suffering from chronic inflammatory diseases, such as rheumatoid arthritis and Kawasaki disease [17,24].