In two cases (LIS_TUB_021_fœtus07 and LIS_TUB_021_ fœtus07), a 4-layered cortex was observed as in LIS1-related lissencephaly, consisting of an upper molecular layer, a second thin cellular layer containing pyramidal neurons usually observed in layer V, a third pale poorly cellular layer and a fourth thick deep layer made up of neurons which had failed to migrate. Here, PAFAH1B1 is linked to lissencephaly spectrum disorders.