SLIT2, exclusively dysregulated in excitatory neurons’ layers 4 to 6, cluster 1, has been linked to depression- and anxiety-like behavior in mice (29), both of which have a substantial symptomatic overlap with bipolar disorder and schizophrenia (41, 42), and the development of serotonergic and dopaminergic circuits in the forebrain (43). This evidence concerns the gene SLIT2 and bipolar disorder.