Distribution of HLA–B27 subtypes in Sardinia and continental Italy and their association with spondylarthropathies

Abstract

The association of spondylarthropathies with HLA–B27 is well documented; however, the presence of HLA–B27 is not uniformly distributed among the different forms of spondylarthropathy. Ankylosing spondylitis (AS) exhibits the strongest degree of association with HLA–B27 and psoriatic arthritis (PsA) exhibits the lowest degree of association. Furthermore, there is no definitive evidence of a role of HLA–B27 molecules in the pathogenesis of any form of disease. It is also not clear if its role is the same in all spondylarthropathies, as the most conservative hypothesis would suggest. In this regard, association data may provide some insights. It has been reported that some HLA–B27 subtypes do not associate with AS: i.e., B*2709 and B*2706 are absent in patients with AS in Sardinia and Southeast Asia, respectively. Much less is known about other forms of spondylarthropathy, especially because their lower degree of association with HLA–B27 makes studying this association more demanding in terms of the number of patients to be analyzed. We analyzed a large cohort of patients from Sardinia and continental Italy with 2 forms of spondylarthropathy: AS (271 patients), and PsA (263 patients). Patients with AS were selected based on fulfillment of the modified New York criteria, and PsA was diagnosed according to the Moll and Wright criteria. Patients and controls were recruited, via a program in conjunction with the Italian Ministry of Education, from several regions of Italy; all gave informed consent. Some of the patients and controls from Sardinia have been described in another report. B27 subtyping was performed using the HLA–B27 high resolution kit (Dynal, New Hyde Park, NY).