**3.5 STAT6 gene**

STAT6 is a transcriptional factor, critical for both IL-4 and IL-13 signals (5, 6). Heterodimerization of type I IL-4R or type II IL-4R/IL-13R by binding of IL-4 or IL-13 activates Jak1, Jak3, or Tyk2, tyrosine kinases associated with IL-4Rα, common γ, and IL-13Rα1 respectively, followed by activation of STAT6. Several SNPs on the *STAT6* gene, 2964G/A, in18SNP1C/T, and GT repeat in exon1 were reported to be associated with serum IgE levels or with eosinophil numbers (43, 44).
