IRF1 and eosinophilic granulomatosis with polyangiitis: GPA33 encodes a cell surface glycoprotein that plays a role in maintaining the barrier function of the intestinal epithelium and bronchial tissue, while IRF1/IL5 interacts with the regulatory regions of IL-4, IL-5, and IRF1 and is associated with increased susceptibility to EGPA, higher eosinophil count, asthma, allergic rhinitis, inflammatory bowel disease, and juvenile idiopathic arthritis [2,6,45,75].