SLIT2 and major depressive disorder: 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).