A useful clustering of asthma susceptibility genes has been proposed [9]: i) triggers of the immune response (such as CD14, IL10, STAT3, MHC class II molecules); ii) regulators of the T helper 2 (Th2) differentiation (IL12B, IL4, IL13, STAT6, IL4RA); iii) associated with epithelial biology (CCL5, FLG, SPINK5, GSDML) and iv) linked to lung function, airway remodeling and asthma severity (ADRB2, ADAM33, DPP10, PHF11). This evidence concerns the gene IL4 and asthma.