A significant number of ASD and SZ candidate genes were among those that were differentially expressed in a comparison of heterozygous KO lines (CHD8+/−) vs isogenic controls (CHD8+/−), including the SZ and bipolar disorder (BD) candidate gene TCF4, which was markedly upregulated in CHD8+/− neuronal cells. This evidence concerns the gene TCF4 and bipolar disorder.