Given evidence that the matrix metalloproteinases (MMPs) play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD), a number of case-control studies have attempted to assess the relationship between genetic polymorphisms in MMP genes and COPD risk. However, reliable measures of these results are lacking.

Material and methods:
We assessed the published evidence for association of the MMP-3, MMP-9 and MMP-12 polymorphisms with COPD risk using meta-analytic techniques. Odds ratio (OR) and 95% confidence intervals (CI) were calculated for each study using fixed or random effect models.

A total of 23 case-control studies were included in the meta-analysis. No significant association was observed between the MMP-9 rs3918242 polymorphism and COPD risk in the overall populations under the dominant (T/T + C/T vs C/C: OR=1.30, 95% CI: 1.00-1.69, P=0.054) and allele contrast (T allele vs C allele: OR=1.22, 95% CI: 0.97-1.53, P=0.088) models. However in sub-group analysis the polymorphism rs3918242 was significant in Asians under the dominant model (T/T + C/T vs C/C: OR=1.66, 95% CI: 1.02-2.72, P=0.043). The results for MMP-12 rs2276109 showed an association with COPD only in mixed populations (G/G + A/G vs A/A: OR=1.57, 95% CI: 1.10-2.24, P=0.013; G allele vs A allele: OR=1.52, 95% CI: 1.09-2.14, P=0.015). We did not find any significant association of the MMP-12 rs652438 and MMP-3 rs35068180 polymorphisms with COPD.

The findings in this meta-analysis suggest that the risk of COPD is associated with the MMP-9 rs3918242 and MMP-12 rs2276109 polymorphisms in certain ethnic groups.