Regarding the different COPD phenotypes, a question remains as to which pharmacologic agent (s), i.e. β2 agonists, antimuscarinics, inhaled or systemic corticosteroids, theophylline, phosphodiesterase-4 (PDE4) inhibitors, mucolytics and macrolides would be optimal for a given phenotype. The gene discussed is PDE4A; the disease is chronic obstructive pulmonary disease.