TNF and juvenile idiopathic arthritis: Only the Iranian study indicated a statistically significant association between A allele of TNF-α 308A/G polymorphism and decreased risk of JIA (OR 0.12, 95% CI 0.03, 0.48; P = .003), whereas the Mexican population showed a significant association between the A allele of TNF-α 308A/G polymorphism and increased risk of JIA (OR 2.21, 95% CI 1.21, 4.05; P = .01)(Fig. 3).