In none of the spondyloarthropathies is the pathogenesis well understood. Much of the investigation into the aetio-pathogenesis of these diseases has focused on the association with HLA-B27 and the known triggering potential of certain infectious agents. In this article the author describes that the HLA linked genes which is subdivided into three groups, class I, class II and class III, which are structurally and functionally distinct from each other.peer-reviewe
