Muco-obstructive diseases in the lung therefore arise from different pathophysiological mechanisms that can involve defective epithelial cilia motility, ion transport and fluid homeostasis, or mucin secretion that results in the accumulation and stasis of mucus in airway compartments, which is not cleared and provides a microenvironment for persistent airflow obstruction, inflammation, and infection. The gene discussed is MUC5AC; the disease is infection.