Mucus as a Treatable Trait in Chronic Airway Diseases.

Chronic airway diseases, including asthma, chronic obstructive pulmonary disease, bronchiectasis, and cystic fibrosis, are increasingly recognized as heterogeneous disorders characterized by overlapping pathophysiological mechanisms. Among these, abnormalities in mucus production, composition, and clearance have been identified as clinically significant contributors to symptoms, airflow limitation, exacerbations, and disease progression. Within the "treatable traits" framework, mucus-related abnormalities represent a distinct, modifiable phenotype that supports personalized management strategies. This narrative review explores mucus as a treatable trait across chronic airways diseases, integrating mechanistic insights with clinical assessment, biomarkers, and current and emerging therapeutic approaches. We discuss the role of mucus in disease phenotyping, its impact on morbidity, and the potential of targeted interventions to improve outcomes. Recognizing mucus as a treatable trait aligns with the principles of precision medicine and offers a pathway toward individualized therapy beyond traditional diagnostic labels.