from multiple centers with as much clinical information as possible. Furthermore, our results confirm previous observations that the effects of unknown, unmeasured, or unquantified covariates can confound genetic effects with structured error sources [19], [36], [2], and that controlling for these hidden confounders substantially boosts the rate of eQTL discovery [23]. Importantly, we demonstrated that not only are more eQTLs detected but that their reproducibility in independent collections of primary human tissue was also significantly higher.
