IL4 and rheumatoid arthritis: Our results showed that the TT genotype carriers had markedly higher risk for RA compared with CC genotype carriers for IL-4 promoter polymorphisms, and the CC genotype carriers had markedly higher risk for RA compared with GG genotype carriers for IL-6 promoter polymorphisms; besides, the T allele of IL-4 promoter polymorphisms and the C allele of IL-6 promoter polymorphisms had shown an association with susceptibility of RA in a Chinese population.