Multivariate linear regression analysis showed that plasma PAI-1 concentrations were associated with PAI-1 4G/5G polymorphism, after controlling for diabetes mellitus, ischemic heart disease and COPD (regression coefficient = 4.82; 95% CI = 3.227 to 6.406; p<0.001) (Table 5). The gene discussed is SERPINE1; the disease is chronic obstructive pulmonary disease.