IL13 and asthma: To validate the assay, we confirmed that CRISPR-mediated targeting of Gata3 efficiently abrogated IL-13Tom expression in virally transduced (BFP+) cells (Extended Fig. 1b) and resulted in the downregulation of 122 genes (4-fold differential expression) including Il4, Il5, Rad5O and Il10 (Il13 transcripts were not detected due to the use of homozygous Il13tdTom alleles), with an enrichment in the asthma-gene-associated pathway (Extended Fig. 1c and d).