Spondyloarthropathies are inflammatory joint diseases of the vertebral column associated with the MHC class I molecule HLA-B27. The term seronegative spondylarthropathy is used by medical practitioners because this set of conditions may mimic rheumatoid diseases such as rheumatoid arthritis, but serological (blood) tests are typically negative for rheumatoid factor (RhF). The closely related term spondylitis implies inflammation. Examples Subgroups (with increased HLA-B27 frequency) are: ankylo… (More on Spondyloarthropathy)