EPHX1 and chronic obstructive pulmonary disease: Pooled analyses revealed that the extremely slow (OR, 1.77; 95% CI, 1.23–2.55) and slow EPHX1 enzyme activity (OR, 1.44; 95% CI, 1.13–1.85) were associated with an increased risk of COPD, while the fast enzyme activity was not associated with a decreased risk of COPD.