The classical form of asthma is considered to be mediated by T helper cell type 2 (Th2) cells and is characterized by eosinophilic inflammation, immunoglobulin (Ig) E reactivity, and the predominance of Th2 cytokines such as interleukin (IL)-4, IL-5, and IL-13 [5]. The gene discussed is IL13; the disease is asthma.