A shared HLA-DRB1 epitope in the DR beta first domain is associated with Vogt-Koyanagi-Harada syndrome in Indian patients

PURPOSE Vogt-Koyanagi-Harada (VKH) disease and sympathetic ophthalmia (SO) are two distinct entities that share common clinical and histopathological features; however, it remains unknown whether they have a common genetic susceptibility. Several studies have shown an association of human leukocyte antigen (HLA)-DR4 with VKH disease in patients of different ethnic backgrounds. We present in this paper the HLA-DRB1 genotyping analysis of a large cohort of VKH patients from southern India and compare these patients to patients with SO and to healthy individuals from the same geographic area. METHODS VKH patients were diagnosed according to the revised criteria of the International Committee on VKH disease. Patients with granulomatous uveitis after ocular trauma or multiple eye surgeries were diagnosed as having SO. Genomic DNA was extracted from all patients and controls. Samples were analyzed for HLA-DRB1 alleles by reverse polymerase chain reaction (PCR) sequence-specific oligonucleotide (SSO) hybridization on microbeads, using the Luminex technology, and by PCR sequence-specific primers (SSP) typing for DRB1*04 allele determination. Strength of associations was estimated by odds ratios (OR) and 95% confidence intervals (CI) and frequencies were compared using the Fisher's exact test. RESULTS HLA-DRB1 alleles were determined in 94 VKH patients, 39 SO patients, and 112 healthy controls. HLA-DRB1*04 frequency was higher in VKH patients (20.2% versus 10.3% in controls; OR=2.2, p=0.005, pc=0.067). This association was lower than the association of HLA-DRB1*04 frequency in cohorts of patients from different origins. No significant DR4 association with SO was detected. HLA-DRB1*0405 and HLA-DRB1*0410 alleles were significantly increased in VKH patients (8.5% versus 0.9% in controls; OR=10.3, 95% CI=2.34-45.5, p<0.001). These two alleles share the epitope S57-LLEQRRAA (67-74) in the third hypervariable region of the HLA-DR molecule. None of the DRB1 alleles was significantly associated with SO. CONCLUSIONS Based on the association of HLA-DRB1*0405 and HLA-DRB1*0410 alleles with VKH disease, we propose that the epitope S57-LLEQRRAA (67-74) in the third hypervariable region of the HLA-DRbeta1 molecule is the relevant susceptibility epitope. This genetic component seems specific to VKH disease since no correlation could be identified in SO patients. The weaker association with HLA-DR4 in this VKH patient cohort compared to VKH patients from northern India is probably related to the lower frequency of HLA-DRB1*0405 in our study group. The HLA-DRB1 association with susceptibility to VKH syndrome seems weaker in Indian patients compared to Japanese or Hispanic patients, suggesting a different non-HLA immunogenetic background in Indian VKH patients.