COPD is strongly associated with smoking, but not all smokers will develop COPD, suggesting that there may be unique genetic differences among individuals leading to greater susceptibility to the most adverse effects of cigarette smoke in some individuals 6. Relatives of COPD patients show an increased prevalence of airflow obstruction, which supports a role for genetic factors predisposing smokers to COPD 7–9. Smokers with first degree relatives affected by COPD have two to three times the risk of developing disease 9;10. Genetic factors have been associated with response to lung volume reduction surgery 11 as well as specific patterns of emphysema 12 and degree of functional impairment 13. Estimated heritability for decline in lung function with age using parent-offspring pairs who both smoke are 0.18 for FEV1 and 0.39 for FVC 14. Because COPD is likely the result of multiple genes, some of which may interact with environment risk factors (primarily smoking), estimates of heritability that do not include the effects of smoking on lung function are likely to underestimate the true genetic component in COPD.
