The anti-interleukin-5 (IL-5) monoclonal antibody mepolizumab and the anti-IL-5 receptor α (IL-5Rα) monoclonal antibody benralizumab, both available in Japan, deplete eosinophils by binding to IL-5 or IL-5Rα, thus ameliorating eosinophilic inflammation of the airways in asthma patients [5]. The gene discussed is IL5RA; the disease is asthma.