histocompatibility hla class i in anterior uveitis patients with and without spondyloarthritis

Anterior uveitis (AU) and ankylosing spondylitis (AS) are associated with histocompatibility human leukocyte antigen (HLA)-B27. Previous genetic studies conducted in different populations have also demonstrated other genetic associations, including HLA, both  general and individual ones for AU and AS.Objective: to investigate the association of HLA class I with AU depending on the presence or absence of spondyloarthritis (SpA).Patients and methods. The investigators used the data of HLA class I typing in the patients referred by ophthalmologists for examination to the V.A. Nasonova Research Institute of  Rheumatology, as well as the previous databases of patients with  AS. The investigation included retrospectively two groups of patients with AU: 1) 52 patients with a confirmed diagnosis of SpA (AU + SpA); 2) 96 patients who had other types of AU (idiopathic AU  (n=52), viral uveitis (n=29), multiple sclerosis (n=2) toxoplasmosis  (n=2), sarcoidosis (n=1), tuberculosis (n=1), chlamydiasis (n=3),  Behcet's disease (n=2), juvenile chronic arthritis (n=3), and Fuchs'  heterochromic cyclitis (n=1). A control group consisted of 150 healthy test donors. The distribution of HLA class I (A, B, and Cw) was analyzed when comparing the two groups of patients with AU and each control patient group. Results. HLA-B27 was detected in 96.1% of cases in the AU + SpA group, in 40.6% in the AU group, and in 7.3% in the controls. In HLA-27-positive patients, the risk (odds ratio (OR) for joint disease  (AU + SpA) was 315.9 (95% confidence interval (CI), 61.9–2176.7); p<0.0000001; the risk for AU was 8.7 (95% CI, 3.9–19.4);  p<0.000001. The HLA-C-locus antigens showed a high incidence of  Cw2 antigen in patients with AU + SpA and in those with AU compared to the controls (64.0, 36.3, and 10.0%, respectively): AU + SpA versus the controls (p<0.000001), AU versus the controls  (p<0.00001). In the two groups of patients with a high HLA-B27  frequency, this substantially higher rate of Cw2 antigen carriage was  natural due to the non-equilibrium coupling phenomenon, including  that for B27 and Cw2 antigens. The rate of Cw7 antigen was significantly lower in the AU + SpA group versus the controls: 12.8 and 38.7% (p=0.002). In the group of AU patients without SpA, the rate of this antigen did not differ significantly from that in the control and AU + SpA groups.Conclusion. The analysis of the distribution of HLA class I confirmed the association of B27 antigen with AU in the Russian population. There were no associations with other antigens other than Cw2. Cw7 antigen can play a protective role against SpA, since the frequency  of this gene was not lower in AU patients compared to the controls.