Off-target effects of several drugs, such as TZDs and DPP4 inhibitors, are also reported, and some are even fatal; for example, TZDs could cause hepatotoxicity, myocardial infarction, bladder cancer, and even liver/heart failure (Nesto et al., 2003; Rogue et al., 2010; Lewis et al., 2011), while DPP4 inhibitors often lead to upper respiratory tract infections and nasopharyngitis (Monami et al., 2011; Karagiannis et al., 2012). This evidence concerns the gene DPP4 and Recurrent upper respiratory tract infections.