Mutations in Gli3 result in a shortened cell cycle, impaired cortical lamination, and cortical neuron formation and are responsible for various morphological CNS abnormalities, such as Greig cephalopolysyndactyly syndrome (GCPS), Pallister-Hall syndrome (PHS) and polydactyly and syndactyly (178). Here, GLI3 is linked to Greig cephalopolysyndactyly syndrome.