Seronegative spondyloarthropathies include several chronic inflammatory arthritic diseases that affect the vertebral column. The most important diseases in this group are , , and . Common features include the absence of rheumatoid factor (RF) and a strong genetic association with HLA-B27. Spondyloarthropathies disproportionately affect men, with symptom onset generally occurring before the age of 45. The cardinal sign is slowly progressive pain in the lower back and sacroiliac joints (especially at night). Asymmetrical oligoarthritis and enthesopathy are also common. The diseases differ in the involvement of other organs, such as the eyes, the genitourinary tract (particularly in reactive arthritis) or the skin (particularly in psoriatic arthritis). Seronegative spondyloarthropathies usually respond well to NSAID therapy.
Types of seronegative spondyloarthropathies
The different types of seronegative spondyloarthropathy do not necessarily represent distinct diseases but may overlap significantly in etiology, pathology, clinical features, and treatment.
Common features of seronegative spondyloarthropathies
- Associations 
- Generally more commonly affect men
- Age of onset: typically between 20–40 years of age
Clinical features 
- Non-specific symptoms (fever, fatigue, weight loss)
- or achillodynia) (e.g.,
- sausage-like appearance: fingers have a
- Extra-articular manifestations vary according to type, but involvement of the eye is common (e.g., iritis, iridocyclitis, uveitis)
- HLA-B27 is a surface antigen that belongs to the class I major histocompatibility complex (). 
- HLA-B27 is strongly associated with seronegative spondyloarthropathies and other autoimmune conditions: