Seronegative arthritis--etiology and diagnosis.

Seronegative arthritis is part of a multifactorial syndrome which also includes acute anterior uveitis (AAU), psoriasis, inflammatory bowel disease and forms of A-V block and aortic incompetence. The whole syndrome may be referred to as HEreditary Multifocal Relapsing Inflammation (HEMRI). Any sign may occur alone or in combinations with others. The signs may be triggered by infections, the arthritic components are then referred to as reactive arthritis. Genetic factors predetermine who is to contract disease when triggered. HLA-B27 itself is probably of major significance in ankylosing spondylitis and AAU. A genetic factor in linkage disequilibrium with HLA B13 and B17 is instrumental in familial psoriasis. Other genetic factors may determine psoriatic arthritis, and possibly also inflammatory bowel disease and juvenile arthritis. The genetic factors interact with each other and with the environmental factors when producing disease. Diagnosis should be based on demonstrated signs of disease. Classification according to genetic factors reflects etiology, disease manifestations and prognosis.