The influence of a TNF gene polymorphism on the severity of rheumatoid arthritis in the Brazilian Amazon

Abstract

Purpose: The aim of this study was to investigate the influence of the TNF -308 G/A polymorphism in the promoter region of the tumor necrosis factor- α gene on the susceptibility and severity of rheumatoid arthritis (RA) in individuals from the Brazilian Amazon. Methods: A total of 323 individuals-192 healthy controls without arthritis and 131 individuals suffering from arthritis-were genotyped for this polymorphism using a methodology based on PCR-RFLP. Results: The frequency of the A allele (TNF2) in rheumatoid arthritis sufferers was not significantly higher than in the controls (p= 0.926; OR = 0.97; confidence interval 0.54-1.76). However, using a logistic regression model, when the patients were stratified according to whether the manifestations were preponderantly articular or systemic, there was a strong association between the TNF2 allele and systemic arthritis (p= 0.001; OR = 5.89; confidence interval = 1.98-17.5) as well as the use of anti-TNF immunotherapy (p= 0.023; OR = 1.10; confidence interval = 1.00-1.14). The main factors that were found to influence the risk of extra-articular disease were age greater than or equal to 60. years (p= 0.008; OR = 4.06; confidence interval = 1.45-11.38), disease duration greater than 10. years (p= 0.031; OR = 3.10; confidence interval = 1.11-8.63) and positive rheumatoid factor (p= 0.035; OR = 2.07; confidence interval = 1.05-4.09). Conclusions: These results suggest that the TNF2 allele is associated with the more serious forms of the disease in individuals from the Brazilian Amazon but not with a risk for developing RA. © 2012 Elsevier Ltd.