MUC5AC and chronic rhinosinusitis: MUC5AC expression was significantly up‐regulated in both chronic rhinosinusitis with nasal polyps (CRSwNP; WMD: 0.52; 95% CI: 0.41–0.63) and chronic rhinosinusitis without nasal polyps (CRSsNP; WMD: 0.42; 95% CI: 0.28–0.56) patients compared to controls.