Chronic obstructive pulmonary disease (COPD) is a global public health concern and is currently the third leading cause of death worldwide.1 Smoking and indoor air pollution are major environmental risk factors for development of COPD, but heritability studies also suggest a strong genetic component in smoking behaviour and in risk of COPD.1–4 Spirometry, particularly measurements of forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC), is used to measure airflow obstruction and helps in the diagnosis and grading of severity of COPD. Previous large genome-wide association studies (GWAS) of general population cohorts have identified 32 common genetic variants (minor allele frequency [MAF] >5%) associated with lung function,5–9 12 of which have also shown association with airflow obstruction and risk of COPD.10–15 However, these findings only explain a small proportion of the phenotypic variance (∼1·5% for FEV1).8
