Spondyloarthropathy in Caucasians and non-Caucasians.

The striking association between the spondyloarthropathies and HLA-B27 transcends all ethnic and geographical boundaries. The relationship between the various entities is well defined for many conditions, but others such as pustulotic arthroosteitis, undifferentiated spondyloarthropathy, and seronegative enthesopathic arthropathy of childhood are less clear. The association between B-27 and disease is less dramatic in non-Caucasians where cross-reacting antigens and other genetic determinants may be more important. Worldwide, some 20% of individuals develop sacroiliitis or Reiter's syndrome following an unknown or specific infective agent, respectively. The debate continues as to whether B27 itself is operative or whether additional gene or genes are required. Detailed epidemiological and molecular analysis is required.