The case–control data are often of modest size; the tissue that is most representative of the disease may be missing in GTEx; some genes or transcripts may have the expression value as 0 for many samples in GTEx (as we observed for SMN2‐specific transcripts); some genes may not have expression measured at all in the case–control samples (as we observed for two previously published CF lung modifier genes). Here, SMN2 is linked to cystic fibrosis.