The ankylosis process<unk>  (AS) is a systemic rheumatic disease, meaning it affects the entire body. 1–2% of individuals with the HLA-B27 genotype develop the disease. Approximately 85% of people with AS express the HLA-B27 genotype, meaning there is a strong genetic association. Tumor necrosis factor-alpha (TNF α) and IL-1 are also implicated in<unk> . Autoantibodies specific for AS have not been identified. Anti-neutrophil cytoplasmic antibodies (ANCAs) are associated with AS, but do not correlate with disease severity. Single nucleotide polymorphism (SNP) A/G variant rs10440635 close to the PTGER4 gene on human chromosome 5 has been associated with an increased number of cases of<unk>  in a population recruited from the United Kingdom, Australia, and Canada. The PTGER4 gene codes for the prostaglandin EP4 receptor (EP4), one of four receptors for prostaglandin E2. Activation of EP4 promotes bone remodeling and deposition (see EP4, bone) and EP4 is highly expressed at vertebral column sites involved in<unk> . These findings suggest that excessive EP4 activation contributes to pathological bone remodeling and deposition in<unk>  and that the A/G variant rs10440635a of PTGER4 predisposes to this disease, possibly by influencing EP4's production or expression pattern. The association of AS with HLA-B27 suggests the condition involves CD8 T cells, which interact with HLA-B. This interaction is not proven to involve a self-antigen, and at least in the related reactive arthritis, which follows infections, the antigens involved are likely to be derived from intracellular microorganisms. There is, however, a possibility that CD4+ T lymphocytes are involved in an aberrant way, since HLA-B27 appears to have a number of unusual properties, including possibly an ability to interact with T cell receptors in association with CD4 (usually CD8+ cytotoxic T cell with HLAB antigen as it is a MHC class 1 antigen). "Bamboo spine" develops when the outer fibers of the fibrous ring (anulus fibrosus disci intervertebralis) of the intervertebral discs ossify, which results in the formation of marginal syndesmophytes between adjoining vertebrae.
Ankylosing spondylitis
Plantar fasciitis
Axial spondyloarthritis
Oligoarthritis
Osteoarthritis
Spondyloarthropathy
Enteropathic arthropathy
Spondylolysis