Currently, an anti-interleukin (IL)-5 biologic agent, mepolizumab, has produced glucocorticoid reduction and protocol-defined remission in fifty perecent of patients with EGPA and has been approved by the United States Food and Drug Administration (FDA) in relapsing/refractory EGPA [2, 3]. The gene discussed is IL5; the disease is eosinophilic granulomatosis with polyangiitis.