In fact, the definition of BA and CRS phenotype/endotype is crucial, taking into account the availability of novel biologic agents, such as anti-IgE, anti-IL-5/IL-5Rα and anti-IL4/IL-13Rα monoclonal antibodies, which can be prescribed to patients with poor or absent responsive to conventional asthma or CRSwNP treatments [21,22,23]. This evidence concerns the gene IL4 and asthma.