In the integrative analysis, each expression probe set was mapped to its corresponding gene and all genotyped SNPs were identified within 50 kb of the transcription start site (TSS). General linear models were used to detect cis-acting associations between probe set expression levels and SNP genotypes, adjusted for age, gender, and the first six genetic ancestry principal components derived from the genotype data on all ECLIPSE COPD cases [29]. False discovery rate adjusted p-value<0.05 defined statistical significance. eQTL analysis utilized the GGTools Bioconductor package [30].
