CHL1 and fragile X syndrome: Pirenperone treatment at 20 μM elevates gene expression of originally downregulated genes in FXS (4.56, 2.04, 1.595, and 1.732 times at LAMB1, CHL1, ANK3, and RIMS3, respectively), where it marginally changes the gene expression of originally upregulated genes (Fig. 2C–I).