Lissencephaly is a genetically heterogeneous disorder, but the LIS1 gene seems to have an important role in this disease, as the complete loss of Lis1 is lethal for the embryo, while LIS1 haploinsufficiency alters neuronal migration through the upregulation of RhoA and the downregulation of Rac1 and Cdc42 activities [106,107]. Here, RAC1 is linked to lissencephaly spectrum disorders.