On the other hand, during the second trimester fetuses with DS exhibit a notable reduction in cortical thickness (Golden and Hyman, 1994; Guidi et al., 2018) and a reduction in the number of cells expressing the radial glia marker SOX2 and of radial glia processes (Hutton and Pevny, 2011; Guidi et al., 2018), which suggests impairment in asymmetrical cell divisions. This evidence concerns the gene SOX2 and Dravet syndrome.