The important adaptor protein CARD9 (caspase recruitment domain-containing protein 9) is involved in signal transduction from a variety of receptors, and mutation in this gene not only leads to mucosal infection but also is associated with IFIs, development of autoimmune diseases, inflammatory bowel disease (IBD), and cancer (Glocker et al., 2009; Drummond et al., 2018). This evidence concerns the gene CARD9 and inflammatory bowel disease.