MMP12 and chronic obstructive pulmonary disease: By two SNPs interaction model, we found positive interaction and the result showed carriers of rs243864 G/G of MMP2 and rs652438 T/T of MMP12, had increased risk for COPD (OR = 12.92; 95% CI, 1.46–114.4, p = 0.021; RERI = 6.94; AP = 0.537; S = 2.395) compared with participants without any of the risk genotypes (Table 6).