Asthma phenotypes/endotypes vary from a predominant type 2 response with increased T helper (Th) 2 cell populations and interleukin (IL)-4, -5, -13 levels to more severe endotypes that have additional presence of type 1 and/or type 17 inflammation, which are associated with corticosteroid insensitivity [9]. This evidence concerns the gene IL4 and asthma.