Adenosine signals through G-coupled receptors (A1R, A2AR, A2BR, and A3) and is a powerful immune modulator to different cells known to participate of the inflammatory response in rheumatoid arthritis and sickle cell disease, such as M1 macrophages and neutrophils [4, 13, 41]. The gene discussed is ADORA2A; the disease is sickle cell disease.