To investigate potential associations between the -174 G/C interleukin-6 (IL-6) promoter polymorphism and susceptibility to and clinical features of giant cell arteritis (GCA), particularly in patients with or without polymyalgia rheumatica (PMR) and with or without ischemic complications.
One hundred and twenty-six patients with biopsy-proven GCA who were residents in Reggio Emilia, Italy, and 112 population-based controls from the same geographic area were genotyped for IL-6 polymorphism at position -174 by molecular methods. Patients were divided in subgroups according to presence or absence of PMR and ischemic complications (visual loss, jaw claudication, cerebrovascular accidents, aortic arch syndrome).
Distribution of the G/C 174 genotype was similar in patients with GCA and controls. No significant associations with the IL-6 promoter polymorphism at position -174 were found when GCA patients with or without PMR or with or without ischemic complications were compared. Further, IL-6 genotypes did not significantly affect levels of C-reactive protein or other inflammatory markers at diagnosis.
Our findings show that the 174 G/C promoter IL-6 polymorphism does not seem to be implicated in susceptibility to and clinical expression of GCA.