Our study has several important strengths. The CHARGE cohorts are well-phenotyped with pulmonary function measures passing stringent quality control criteria, thus minimizing measurement error. Our large sample size of 20,890 participants offers a powerful resource to examine associations of common SNPs with modest to large effects14. However, we likely have insufficient power to detect associations of polymorphisms with small effect sizes or low frequencies. Replication in an independent consortium with similar power offered the opportunity to confirm true genetic associations.
