even when the gene expression data has a small number of samples per tissue/cell type, in contrast to eQTL-based methods. Finally, we note that a recent study86 tested 30 phenotypes for tissue-specific enrichment in 44 tissues from GTEx using the TWAS approach87 but concluded that their results “did not suggest tissue-specific enrichment at the current sample sizes.” We share their hypothesis that this is because eQTLs are often shared across tissues even when overall expression levels are very different.
