Effect of sample size and MAF on power to detect eQTLs. (a) Power for cis-eQTL analysis in which we assume α = 0.05/200,000, reflecting Bonferroni correction for 200,000 hypotheses based on 20,000 genes and an average of 10 non-redundant SNPs in the region ±100 kb of each gene. (b) Power for trans-eQTL analysis in which we test 20,000 genes against 5 million SNPS in a total of 1 × 1011 tests with α = 5 × 10−13.