USP18 and brain disorder: These genes were selected based on either our recently identified zebrafish microglia transcriptome (e.g. slco2b1, hcst and mrc1b), microglia-expressed genes with a connection to brain disease (e.g. usp18), or genes that can affect microglia in a non-cell-autonomous manner (Csf1r-ligand-encoding genes il34, csf1a and csf1b) (Fig. 3A; Fig. S1, Table S1) (Oosterhof et al., 2017).