Interleukin-18 gene polymorphism, but not interleukin-2 gene polymorphism, is associated with rheumatoid arthritis.

To investigate whether polymorphisms of IL-2 and IL-18 genes are associated with rheumatoid arthritis (RA), polymorphisms of IL-2 and IL-18 genes were detected by polymerase-chain-reaction-based restriction analysis in the patients with RA and normal controls. The results for the IL-18 gene revealed a significant difference between the patients and the normal controls (p = 0.000003), but there was no significant difference for the IL-2 gene (p = 0.876). The IL-18 gene 105A allele was associated with RA in Chinese patients. Individuals possessing the 105A allele had a higher incidence of RA. A lack of association of IL-2 gene polymorphism between RA patients and healthy individuals was noted. The results of this study provide genetic evidence that IL-18-105A/C polymorphism may play an effective role in RA.