IL-4, together with IL-5 and IL-13, are Type 2 (T2)-high asthma-associated cytokines that are assumed to provide the main asthma manifestations, such as bronchial hyperreactivity, mucus hyperproduction, immunoglobulin E (IgE) synthesis, and airway eosinophilia [22,23]. The gene discussed is IL5; the disease is asthma.