Interleukin-23 (IL-23) is vital for the activation of effector functions in group 3 innate lymphoid cells (ILC3s) and IL-17–producing T helper (Th17) cells, which have a pivotal role in gut homeostasis, but have also been implicated in the pathogenesis of inflammatory bowel diseases (Maloy and Kullberg, 2008; Zeng et al., 2019). Here, IL23A is linked to inflammatory bowel disease.