Highlights • Mutations in Sip1 cause the Mowat-Wilson syndrome in humans. • Sip1 controls the formation of the hippocampus. • Sip1 is important for cell fate switch in the neocortex development. • Sip1 controls migration of interneurons and is required for the onset of gliogenesis. • Sip1 is needed for axonal growth and branching. Abstract Zeb2 (Sip1, Zfhx1b) is a transcription factor that plays essential role in neuronal development. Sip1 mutation in humans was shown to cause Mowat-Wilson syndrome, a syndromic form of Hirschprung's disease. Affected individuals exhibit multiple severe neurodevelopmental defects. Zeb2 can act as both transcriptional repressor and activator. It controls expression of a wide number of genes that regulate various aspects of neuronal development. This review addresses the molecular pathways acting downstream of Zeb2 that cause brain development disorders. [ABSTRACT FROM AUTHOR]