IL-23 and IL-17 are crucial in the pathogenesis of psoriasis, EAE, CIA, IBD (Cua et al., 2003; Murphy et al., 2003; Wilson et al., 2007; Tonel et al., 2010) and LAD1 (Moutsopoulos et al., 2017). The gene discussed is IL17A; the disease is inflammatory bowel disease.