IL18 and temporal arteritis: In this regard, an increased susceptibility to GCA was observed in individuals carrying the IL18-1297 C/C or the IL18-1297 C/T genotypes (IL18-1297 C/C) plus T/C genotypes versus T/T genotype in GCA patients compared with controls: P = 0.005; OR, 1.61; 95% CI, 1.15-2.25).