Interleukin–1 receptor antagonist gene polymorphism as a disease severity factor in systemic lupus erythematosus

Abstract

Objective. We have previously described associations between an allele of the interleukin–1 receptor antagonist gene (IL1RN) and several inflammatory diseases. In this study we tested the IL1RN gene as a possible marker in patients with systemic lupus erythematosus (SLE). Methods. Eighty–one SLE patients and 261 ethnically matched control subjects were genotyped by polymerase chain reaction. Results. We found an increase in both frequency and carriage rate of IL1RN*2 in the SLE group. This association strengthened with extensive disease and particularly with the presence of photosensitivity and discoid skin lesions. Conclusion. We describe a novel association between IL1RN*2 and SLE. Carriage of the allele seems to influence severity rather than susceptibility to SLE. We postulate that the association of this polymorphism with disease severity is a widespread feature of common inflammatory and autoimmune diseases.