HLA-B39 and the axial type of psoriatic arthritis

The frequency distribution of HLA-B38 and HLA-B39 was studied in a group of 50 unrelated psoriatic arthritis patients. A high increase of HLA-B39 was noted in the subgroup with axial arthropathy. All B39 positive patients presented with spondylitis and/or sacroiliitis. The hypothesis is formulated that HLA-B39 may discriminate a genetic subset of psoriatic arthritis characterized by a particular susceptibility to develop axial involvement.