Interferon gamma gene polymorphism and susceptibility to, and severity of, rheumatoid arthritis

A strong association between an interferon gamma (IFN-γ) gene polymorphism and rheumatoid arthritis susceptibility and severity has been reported in a case-control study. We investigated this polymorphism in 103 patients with early rheumatoid arthritis and 130 controls. Severity of rheumatoid arthritis was measured after 4-year follow-up with a validated radiographic score. The median radiographic score in patients increased from 1 (IQR 0–4) to 11·5 (2–35) over the 4-year follow up. The distribution of IFN-γ alleles did not differ between patients and controls, and the distribution of radiographic scores did not differ among patients carrying the different IFN-γ alleles. We have failed to confirm the association between the IFN-γ gene polymorphism and rheumatoid arthritis susceptibility or severity.