The choice of biologic therapy often hinges on the patient’s specific phenotype: omalizumab or dupilumab may be suitable for allergic asthma with normal eosinophils; anti-IL-5 or dupilumab is preferred in eosinophilic, non-allergic asthma; and in patients with comorbid conditions such as atopic dermatitis or nasal polyposis, dupilumab emerges as a particularly compelling option. The gene discussed is IL5; the disease is allergic asthma.