CRS may be differentiated in CRS without nasal polyps and with nasal polyps (CRSwNP), the latter being characterized by a TH2-driven inflammatory process with increased levels of interleukin (IL)-5, infiltration of eosinophils, eosinophil cationic protein (ECP), and local immunoglobulin (Ig)E production. The gene discussed is IL5; the disease is nasal cavity polyp.