HLA and idiopathic uveitis.

Idiopathic uveitis is the most common form of chronic uveitis seen in our area. Characteristically it is a heterogeneous entity in its clinical severity, evolution and therapeutic response, and immune mechanisms are thought to be involved. The phenotype frequencies of HLA antigens were studied in 62 patients with idiopathic uveitis and compared with their frequencies in northern Portugal. The authors also included two groups with a well known immunogenetic background-Behçet's syndrome (BS: n=20) and ankylosing spondylitis (AS: n=18) which are, respectively, the most severe and the most frequent of the rheumatic forms in the area. An increased frequency of HLA B5(B51) in Behçet uveitis (55%; RR=8) was confirmed in the authors' population. They also found in idiopathic uveitis an increased risk for HLA B27 (RR=14). HLA B27 positive idiopathic uveitis was predominantly unilateral (80%) and anterior (97%), whereas B27 negative forms showed a higher prevalence of severe panuveitis. In conclusion, the authors confirmed in their population the association of HLA B27 with uveitis, and HLA B51 with Behçet uveitis. In this last entity an intermediate frequency between northern Europe and the Mediterranean area was observed.