Histamine has been shown to act as pro-inflammatory mediator in IBD (Bene et al., 2004; Neumann and Seifert, 2014) and blockade of H4R has proven to ameliorate DSS-induced colitis in mice as well as in TNBS-induced colitis in rats (Varga et al., 2005; Schirmer et al., 2015). The gene discussed is HRH4; the disease is inflammatory bowel disease.