Although recombinant human deoxyribonuclease I (rhDNase) and hypertonic saline are effective in patients with CF [11–13], they have not shown efficacy in COPD or bronchiectasis [14–17], and there is a high unmet need for a well-tolerated and effective mucolytic for COPD and other muco-obstructive lung diseases. The gene discussed is DNASE1; the disease is chronic obstructive pulmonary disease.