The Effects of Gene Polymorphisms in Interleukin-4 and Interleukin-6 on the Susceptibility of Rheumatoid Arthritis in a Chinese Population

BACKGROUND Interleukin-4 (IL-4) and interleukin-6 (IL-6) have been reported to associate with pathogenesis of rheumatoid arthritis (RA); however, the role of IL-4 and IL-6 genetic polymorphisms in RA remains unknown. METHOD A total of 752 unrelated Chinese patients with RA and 798 healthy Chinese volunteers with no family histories of any autoimmune diseases were recruited. The promoter IL-4-590 C/T and IL-6-174 G/C polymorphisms were genotyped. RESULT The genotype distributions and allele frequencies of IL-4-590 C/T and IL-6-174 G/C polymorphisms in RA patients were significantly different from healthy volunteers. Statistically significant differences were observed in genotypes for IL-4-590 and IL-6-174. The frequencies of both the T allele on the IL-4-590 and the C on the IL-6-174 were significantly increased in RA patients. CONCLUSION The IL-4-590 and IL-6-174 promoter polymorphisms may be associated with increased risk of RA and could be used as genetic marker for assessing the susceptibility and severity of RA in Chinese.