Figure 3

The genetic variants identified as being associated with increased COPD risk in different groups of subjects of the follow-up stage. In different periods of the first stage, the COPD risk variants were identified by genotype comparison of COPD subjects with healthy controls who were at COPD risk. By contrast, the common variants were considered to have less bias and to be more reliable. Since the cases from controls and their healthy controls in 2010 were part of the control individuals in 1992, some COPD risk variants may be not be identified.