With weak evidence, IL-18 -607 A/C polymorphisms were associated with a reduced risk of RA susceptibility using the allele model (OR = 0.76, 95% CI: 0.61 − 0.93, p=0.01), dominant model (OR = 0.67, 95% CI: 0.50 − 0.90, p=0.008), homozygote model (OR = 0.57, 95% CI: 0.35 − 0.91, p=0.02), and heterozygote model (OR = 0.71, 95% CI: 0.54 − 0.93, p=0.01) in the overall population. The gene discussed is IL18; the disease is rheumatoid arthritis.