IL4R and asthma: These findings are clinically relevant if periostin is used in the future to guide management and treatment decisions such as identifying patients with eosinophilic airways inflammation, those at risk of FEV1 decline and/or increased asthma exacerbation risk, or who might most benefit from treatment with monoclonal antibody therapy directed against Type 2-related pathways including IL-4Rα, IL-13 and IgE in asthma.