The diagnosis of RA is based on physical examination (according to the European League Against Rheumatism—EULAR criteria) [67], clinical history, and laboratory tests (presence of ACPAs and/or RF antibodies, abnormal acute phase reactants such as CRP and ESR), and also by imaging methods, such as magnetic resonance imaging (MRI) and ultrasonography methods [68]. The gene discussed is CRP; the disease is rheumatoid arthritis.