For example, in the FOXG1 syndrome where haploinsufficiency of the Forkhead transcription factor induces a microcephaly that is associated with severe intellectual disability, motor delay, epilepsy, and delayed myelination, both oligodendrocytes and GABAergic interneurons were found to be reduced, in addition to cortical lamination defects [83]. This evidence concerns the gene FOXG1 and Intellectual disability.