Objective: Since ulcerative colitis and Crohn's disease, which are associated with ankylosing spondylitis (AS), have been found to be variably associated with the IL-1B and the IL-1RN genes encoding interleukin-1beta (IL-1beta) and the interleukin-1 receptor antagonist (IL-1ra), we have investigated whether these polymorphisms in IL-1B and IL-1RN are also involved in AS.
Methods: DNA was isolated from peripheral blood of 106 patients with AS and 104 healthy controls. All patients and controls were Dutch Caucasians. Bi-allelic polymorphisms at positions +3,953 and -511 in the IL-1B gene, and a penta-allelic polymorphism in intron 2 of the IL-1RN gene were studied by polymerase chain reaction-based methods.
Results: Allele IL-1RN*2 was significantly increased in AS (odds ratio=1.60; 95% confidence interval=1.20-2.80; P=0.031) compared with healthy controls, and independent from the polymorphism in loci IL-1B-511 and IL-1B+3,953. No significant associations were found between AS and the IL-1B-511 or IL-1B+3,953 polymorphisms.
Conclusion: Similar to other chronic inflammatory diseases, AS is associated with the IL-1RN*2 allele. Further studies are necessary to determine the biological significance of these findings in relation to susceptibility or severity of the disease.