Decreased HDAC activity was also shown in COPD patients compared with smokers (1.41±0.18 RFU/μg vs. 4.51±0.59 RFU/μg, P < .0001) and nonsmokers (1.41±0.18 RFU/μg vs. 40 6.51±0.51 RFU/μg, P < .001) (Fig 1C). The gene discussed is HDAC9; the disease is chronic obstructive pulmonary disease.