Polymorphisms within the Tumor Necrosis Factor–α Promoter Region in Patients with HLA-B27–Associated Uveitis: Association with Susceptibility and Clinical Manifestations

Purpose The existence of genetic variations in a number of cytokines has been considered to influence susceptibility or relate to disease severity in various autoimmune diseases. Among these, single-nucleotide polymorphisms (SNPs) of the tumor necrosis factor α (TNF-α) promoter at nucleotides -308 and -238 are considered to be protective against inflammation in HLA-B27–positive individuals, whereas the SNP at position -857 has been associated with disease development in anterior uveitis. We investigate a hypothesized association between the TNF-α -857 C-to-T, -308 G-to-A, and the TNF-α -238 G-to-A SNPs and the presence of HLA-B27–associated uveitis. Design Retrospective case–control study. Participants One hundred fourteen Caucasian patients with HLA-B27–associated uveitis were studied. Mean age of patients was 44.9±14 years (range, 16–81), and mean duration of HLA-B27–associated uveitis was 115.6±104 months (range, 6 months–51 years). Eighty-six patients (75.4%) suffered from an additional systemic manifestation of the disease. Sixty-three unrelated healthy HLA-B27–positive blood donors and 88 unrelated healthy HLA-B27–negative individuals served as controls. Methods Genotypes were determined by polymerase chain reaction. Main Outcome Parameters Association of genotypes at positions -857, -308, and -238 of the TNF-α gene with disease development. Results Frequencies of the TNF-α -308GA and TNF-α -238GA genotypes were significantly lower in patients with HLA-B27–associated uveitis (6.1% and 0%, respectively) when compared with the HLA-B27–negative control group, 23% at -308 ( P = 0.003), and 7.9% at -238 ( P = 0.0003). When compared with healthy HLA-B27–positive controls, a significantly lower frequency of the TNF-α -238GA genotype was found among patients (6.3%, P = 0.015). The frequency of the TNF-α -308GA genotype was also found to be lower in patients than among HLA-B27–positive control subjects, without, however, reaching statistical significance (6.1%, P = 0.07). No difference in frequencies was seen among the different groups for the SNPs at position -857. Conclusion Our data suggest that HLA-B27–positive individuals show a higher susceptibility towards development of an intraocular inflammation in the presence of an A allele at nucleotide -238 and, to a lesser degree, at nucleotide -308 of the TNF-α gene promoter.