The GTEx project recently completed an initial pilot phase during which they collected and analyzed multiple human tissues from donors who are also densely genotyped using high density SNP and exome arrays. RNA expression was profiled on multiple tissues from these donors by both array-based methods and RNA sequencing, to an average depth of 50 million reads. Thereby, variations in gene expression that are highly correlated with genetic variation can be identified as expression quantitative trait loci, or eQTLs.