Recent findings from the SPIROMICS (SubPopulations and InteRmediate Outcome Measures In COPD Study) cohort have shown that total mucin concentrations in sputum during stable periods are higher in patients with COPD who experienced 2 or more exacerbations compared with those with zero exacerbations (7, 10). The gene discussed is MUC5AC; the disease is chronic obstructive pulmonary disease.