High prevalence of HLA-All in Thai seronegative spondyloarthropathies.

Forty-three patients with an established diagnosis of seronegative spondyloarthropathies (SNSA) were studied. There was an increase in the prevalence of HLA-All and HLA-B27 compared to controls. Twenty-nine of 43 patients (67%) studied had HLA-All and 29 also had B27 compared to 30.4% and 5.1%, respectively, in the controls (p less than 0.001 and less than 0.0001, respectively). The occurrence of HLA-B27 and HLA-All phenotype was not significantly associated in either the patient or the control groups (p greater than 0.75). These observations strengthen the hypothesis that genetic determinants in addition to HLA-B27 are of importance in the pathogenesis of SNSA.