Ankylosing spondylitis and reactive arthritis in the developing world.

Spondylarthropathies revolve around the strongest known contributing factor, HLA-B27. However, the role of HLA-B27 remains unclear. Its subtypes are reported here in the particular context of developing countries. Non-MHC factors are also being described. The role of immunity is being elucidated. Cytokine expression has been proved to play a major role in ankylosing spondylitis (AS). Recently shown are IL23R, which encodes a critical cytokine receptor in the TH17 subset of T cells, and ARTS1, loss of function of which could have pro-inflammatory effects. This constitutes a major breakthrough in the understanding of AS which could potentially lead to a therapy. New imaging techniques and therapies have substantially improved the earlier diagnosis and management of the disease. However, criteria for an early diagnosis remain to be settled. Such criteria are particularly important for developing countries where they could help in decreasing the socioeconomic burden of the disease.