NFKB1 and juvenile idiopathic arthritis: Analysis of the NFKB1 rs28362491 polymorphic locus showed that the NFKB1 rs28362491*DD genotype was significantly more common, and the NFKB1 rs28362491*I allele was significantly less common in JIA patients with the absence of the response to methotrexate than in those with its presence (*DD: 31.03% vs. 13.26%, P = 0.005, pcor = 0.004, OR = 2.944, 95% CI 1.484–5.938; *I: 48.28% vs. 59.94%, P = 0.031, pcor = 0.033, OR = 0.624, 95% CI 0.410–0.944, respectively).