The IL-4 gene promoter contains a number of polymorphic loci, which were reported to influence the susceptibility of many diseases, including the IL-4-33C/T [35], IL-4-589C/T [36], and IL-4-590C/T [20, 37, 38]; especially, the genotype and allele frequencies of IL-4-590C/T were well studied and reported to be associated with many diseases, such as rheumatoid arthritis [3, 20], liver disease [37], and gastric cancer [38]. This evidence concerns the gene IL4 and rheumatoid arthritis.