In multiple logistic regression analysis of the total population (COPD and controls), after adjusting for age, sex, BMI, smoking status, ADMA/arginine ratio, TBARS, PSH, PON and taurine, only PSH (OR 0.44, 95% CI 0.25–0.77; p = 0.004) and ADMA/Arginine ratio (OR 172, 95% CI 2.27–13,055; p = 0.02) were independently associated with presence of COPD. The gene discussed is PON1; the disease is chronic obstructive pulmonary disease.