HLA and the Spondyloarthritis

Abstract

The Spondyloarthritis are a group of diseases with a strong tendency for family agregation, which includes mainly Ankylosing Spondylitis (AS), Reiter‘s Syndrome / Reactive Arthritis (ReA), Enteropathic Spondylitis (Crohn‘s disease and Ulcerative Colitis), Psoriatic Arthropathy (PsA), and Undifferentiated Spondylitis (uSpA). The axial skeleton, mainly the sacroiliac joints, the peripheral joints – more frequently in the lower limbs, and the tendon insertions (enthesis), are particularly prone to an inflammatory process that may involve several targets at the same time or sequentially. Main symptoms depend on the stage of the disease or the SpA subset under examination, and their overlap is frequent. The most known subset of the SpA is Ankylosing Spondylitis, a chronic systemic inflammatory disease of the axial skeleton whose etiology is still unknown, affecting always the sacroiliac, and usually the apophyseal, costovertebral, and costotransverse joints of the spine. The symptoms begin in late adolescence or early adulthood, and chronic inflammatory back pain and stiffness are the most common and characteristic initial presenting complaints in adult-onset AS. The description in 1973 of a very strong association between HLA-B27, an immune response gene and AS permitted to consider this disease to have an autoimmune pathogenesis. The association of AS with HLA-B27 may be 95% to 99% according with the majority of authors but this proportion is inferior in Reiter‘s Syndrome and Psoriatic Arthritis.