Role of the rs6822844 gene polymorphism at the IL2-IL21 region in biopsy-proven giant cell arteritis.

Objective: To assess the influence of the interleukin (IL)2-IL21 rs6822844 G/T polymorphism in the susceptibility to biopsy-proven giant cell arteritis (GCA) and in the clinical spectrum of manifestations of this vasculitis.

Methods: Two hundred and seventy-two biopsy-proven GCA patients were included in this study. DNA from patients and matched controls (n=791) was obtained from peripheral blood. Samples were genotyped for the rs6822844 polymorphism using a predesigned TaqMan allele discrimination assay and by polymerase chain reaction amplification.

Results: No significant differences in the allele and genotype frequencies between biopsy-proven GCA patients and controls were observed. However, the stratification of GCA patients disclosed some differences according to gender and ischemic manifestations of the disease. In this regard, the frequency of the minor allele T was increased in males (14.8%) compared to females (8.4%) (odds ratio-OR:1.89 (95% confidence interval-CI: 1.09-3.28); p=0.02; Bonferroni adjustment p=0.12). Also, minor allele T frequency was increased in GCA patients with severe ischemic complications (12.8%) compared to those without severe ischemic complications (7.7%) (OR:1.72 (95% CI: 0.97-3.05); p=0.05; Bonferroni adjustment p=0.30), and specifically in patients with jaw claudication (13.7% versus 8.2% in those without jaw claudication; OR:1.76 (95% CI: 1.02-3.04); p=0.04; Bonferroni adjustment p=0.24).

Conclusions: IL2-IL21 rs6822844 polymorphism does not appear to be a genetic risk factor for susceptibility to biopsy-proven GCA. However, this gene polymorphism may contribute to the different phenotypic expression of this vasculitis, in particular in the development of ischemic complications of the disease.