HLA-B27+ acute anterior uveitis and other antigens of the major histocompatibility complex

Acute anterior uveitis (AAU) is associated with HLA-B27 in 50% of the patients. Although the association between HLA-B27 and AAU is evident, other genetic factors probably also play a pathogenic role. To investigate whether HLA-B27 only serves as a marker gene for genes next to the B-locus, class I and II HLA antigens of 62 HLA-B27+ AAU patients were determined. Increased frequencies were found for HLA-Cw1, Cw2, DR4, DRw12 and DQw3 if the AAU patients were compared with normal controls. However, when the data were compared to a group of HLA-B27+ controls, no differences were observed. The supposed associations were therefore probably due to linkage disequilibrium with HLA-B27. Homozygosity for HLA-B27 seemed not to increase the chance to acquire AAU. HLA-DR4 was present less frequently in AAU patients with ankylosing spondylitis than in AAU patients without this disease. Haplotype analysis of 21 families revealed that not all relatives suffering from AAU shared the HLA-B27+ haplotype with the proband. Of seven relatives suffering from AAU, five carried the same HLA-B27+ haplotype as the proband, one had inherited another HLA-B27+ haplotype and the last one was HLA-B27-. In conclusion, we could not bring forward any reason to suggest that genes on the short arm of chromosome 6--other than HLA-B27--play a role in the pathogenesis of HLA-B27+ AAU.