YWHAE and lissencephaly spectrum disorders: Creation of a Crk/Pafah1b1 double knockout could help determine if deletion of these genes contributes to the lissencephaly phenotype in a dose-dependent manner, as this seems to be the case when CRK and YWHAE are deleted together in humans (Tenney et al., 2011; Barros Fontes et al., 2017).