Objectives:
Idiopathic uveitis is the most common form of uveitis in most countries. Uveitis affects about 40–80% of patients with Behçet’s disease (BD). Class I, HLA-B5, and its subclass B51 allele have the strongest association with BD, but its role in idiopathic uveitis is unclear. The aim of this study was to determine the frequency of HLA-B5, HLA-B51 and HLA-B27 in patients with idiopathic uveitis, BD and the control group.

Material and methods:
Forty-eight patients with idiopathic uveitis, 62 patients with BD, and 49 control subjects were compared. The presence of HLA-B5, HLA-B51 and HLA-B27 was checked by reviewing the charts of patients with idiopathic uveitis and Behçet’s disease referred to the rheumatologic center of Shiraz University of Medical Sciences. The control group consisted of a sex-matched normal control population, among which HLA typing was done.

Results:
HLA-B5 was significantly higher in patients with idiopathic uveitis and BD compared to the control group (p = 0.029 and 0.0001). It was significantly higher in patients with BD compared to those with idiopathic uveitis (p = 0.001). The difference of HLA-B51 between the groups was not statistically significant although it was higher in the BD group than the controls. The presence of HLA-B51 was significantly associated with ocular involvement in the BD group (p = 0.013). HLA-B27 was the least common type of HLA in all groups.

Conclusions:
HLA-B5 was the most common, compared to HLA-B51 and HLA-27, in patients with idiopathic uveitis and BD. There was an association between HLA-B51 positivity and ocular involvement in patients with BD. It seems that the pattern of HLA in our patients with idiopathic uveitis was different from that observed in some other studies.