TNF-α gene polymorphisms and juvenile idiopathic arthritis: Influence on disease outcome and therapeutic response

Objective: To investigate the genetic contribution of TNF-α gene polymorphisms on the disease course and therapeutic response in patients with juvenile idiopathic arthritis (JIA).

Methods: 74 Caucasian patients with JIA were recruited with a control group of 77 healthy children. DNA was extracted for analysis of TNF-α gene promoter polymorphisms at positions -163, -244, -238, -376, and -308.

Results: No SNPs at position -163 were observed, while we observed only SNPs at positions -244 and -376 in the controls. No differences were observed in the prevalence of SNPs at -238 and -308 between JIA and controls. In JIA patients no significant differences were observed between the -238 and -308 G/A genotypes and different disease phenotypes. We observed a significant lower disease activity expressed in the carriers of -308 GG genotype with respect to GA and AA genotypes after 6 (p = 0.008 and p = 0.013, respectively) and 12 months of disease (p = 0.02 and p = 0.08, respectively). Also the -238 GG genotypes showed a better disease course after 12 months of disease. Moreover, the -238/-308 GG genotypes presented the higher reduction of disease activity both after 6 (p < 0.01 vs GA and p < 0.01 vs AA) and 12 months from baseline (p < 0.01 vs GA and p < 0.01 vs AA). After 12 months of biologic therapy, a significant higher disease activity was observed in patients with genotype -308 AA respect to both GA (p = 0.012) and GG (p = 0.016).

Conclusions: JIA patients carrying the TNF-α -308 GA/AA and -238 GA genotypes are associated with a worse prognosis and with a lower response to anti-TNF-α drugs.