Higher frequency of allele 2 of the interleukin-1 receptor antagonist genein patients with juvenile idiopathic arthritis

Objective. An increased incidence of allele 2 of the interleukin-1 receptor antagonist gene (IL1RN*2) in several inflammatory diseases has recently be en reported. The aim of this study was to examine a variable number tandem repeat (VNTR) polymorphism of the IL1RN gene in patients with juvenile idio pathic arthritis (JIA). Methods. Findings in 185 Czech patients with JIA were compared with those i n 168 Czech controls, 50 JIA patients and 52 controls of Turkish origin, an d 79 controls from central England. VNTR polymorphism analysis of IL1RN was performed by polymerase chain reaction using 2 flanking primers to amplify an 86-bp tandem repeat region in intron 2. Results. The frequency and carriage rate of IL1RN*2 were significantly incr eased in Czech JIA patients compared with the Czech controls (frequency 27. 6% versus 15.8%; carriage rate 44.3% versus 26.2%). Increased frequency and carriage rate of IL1RN*2 were found in 23.3% and 40.0% of Turkish JIA pati ents and in 17.3% and 34.6% of ethnically matched controls. The high repres entation of IL1RN*2 in 52.3% of the 22 patients with extended oligoarthriti s, 31.3% of the 56 patients with enthesitis-related arthritis, and 42.9% of the 14 patients with other arthritis was particularly responsible for the increased frequency of IL1RN*2 in the Czech JIA patients. We found no assoc iation of IL1RN*2 with disease activity or severity parameters. Conclusion. Inheritance of IL1RN*2 may contribute to genetic susceptibility in several forms of autoimmune diseases, including JIA. The IL1RN*2 allele may be useful as a prognostic indicator of the evolution of an extended ol igoarticular course of JIA.