NPPB and chronic obstructive pulmonary disease: The percentage of the rs198389 site homozygous mutation of the BNP gene in the COPD group was significantly higher than that of the control group (adjusted OR = 1.265, 95% CI = 1.100–1.407, P=0.001), and the risk of COPD in the G allele carriers increased significantly (adjusted OR = 1.165, 95% CI = 1.076–1.254, P<0.001).