Objective: To examine whether severe rheumatoid arthritis (RA) carries a -238 or +489 tumor necrosis factor-alpha (TNF-alpha) genotype different from mild-moderate RA.
Methods: We investigated 163 patients (66 with severe disease) and 67 healthy blood donor controls. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism.
Results: Patients with severe RA (all active disease despite disease modifying antirheumatic drug combination therapy) disclosed the -238 GG genotype in 100% of cases versus 92.8% of the mild-moderates and 92.5% of controls (OR 11.7, Cl 0.6-216, p = 0.03). The +489 AA genotype was seen less often in patients than in controls (OR 4.2. CI 0.97-18.4, p = 0.045), and the contribution to this trend appeared predominant in the anti-TNF treated subgroup.
Conclusion: The -238 AG genotype was absent in severe RA; in contrast, patients with mild-moderate RA disclosed the same frequency as controls. Thus -238 GG homozygosity is associated with severe RA. The +489 AA genotype might instead protect against worse outcome in RA.