Fcγ receptor type IIIA genotype and response to tumor necrosis factor α-blocking agents in patients with rheumatoid arthritis

Objective. To determine whether a functional single-nucleotide polymorphism in the gene encoding Fc gamma receptor type IIIA (Fc gamma RIIIA) correlates with the response to treatment with tumor necrosis factor a inhibitors in rheumatoid arthritis (RA). Methods. The study population comprised 282 Swedish patients with RA in whom the therapeutic efficacy of conventional disease-modifying antirheumatic drugs had been insufficient. Infliximab or etanercept treatment was initiated, and patients were evaluated after 3 months, using the American College of Rheumatology 20% improvement criteria (ACR20), the ACR50, and the ACR70 or the European League Against Rheumatism (EULAR) criteria. The chi-square test was used to compare response rates across Fc gamma RIIIA genotypes. Results. No differences in genotype distribution were observed among nonresponders compared with ACR20 responders (P = 0.80), ACR50 responders (P = 0.56), or ACR70 responders (P = 0.91). Similar results were observed when analyzing infliximab and etanercept separately or when using the EULAR response criteria. Conclusion. Unlike the findings of a previous study, the results of the current study suggest that the 158V/F polymorphism of Fc gamma RIIIA is very unlikely to influence the clinical efficacy of infliximab or etanercept in patients with RA.