IL18 and rheumatoid arthritis: IL-18 gene polymorphisms and RA susceptibility are affected by ethnicity: With weak evidence, IL-18 -137 C/G polymorphisms were related to reduce RA susceptibility in the Asian population (allele model: OR = 0.59, 95% CI: 0.40 − 0.88, p=0.01; dominant model: OR = 0.57, 95% CI: 0.37 − 0.89, p=0.01; heterozygote model: OR = 0.60, 95% CI: 0.38 − 0.94, p=0.03).