Because the relative effects of the haplotypes were very large, we further assessed the explained phenotypic variance of CPD (Table 1). We observed that the haplotypes at the CYP2A6 locus significantly explain 2% of the phenotypic variance in CPD ( for the GWAS set). We also found that the liability variance explained by the haplotypes to be 4% and 1% for COPD and lung cancer, respectively (likelihood ratio test and , respectively).
