Therefore, the aim of this study was to test the level and diagnostic value of anti-CD74 IgG and IgA antibodies in a “real life” diagnostic setting using patients with axSpA and patients with chronic back pain (CBP) from a cohort of patients with early back pain, the spondyloarthritis caught early (SPACE) cohort. The gene discussed is CD79A; the disease is spondyloarthropathy.