The classification of asthma into two phenotypes is generally accepted, from the point of view of immune response; the so-called “T2-high” whose essential characteristics are the overexpression of the immune type 2 (TH2) ways, that is to say of the IL-4 and IL-13 genes and which also shows in adults, the highest sputum eosinophilia and exhaled nitric oxide fraction, and was restricted to severe asthma that involves oral corticosteroid dependency, frequent episodes and severe airflow obstruction [27]. This evidence concerns the gene IL4 and asthma.