CARD9 and infection: Immune response in the gastrointestinal tract requires transmigration of various circulating leukocytes to the site of infection/damage, which is mediated by interleukin 7 (IL7); Caspase recruitment domain family, member 9 (CARD9); and Fc fragment of IgE, high affinity I, receptor for gamma polypeptide (FCER1G) [28,29,30,31].