PAFAH1B1 and lissencephaly spectrum disorders: Our recent studies with human-induced pluripotent stem cells (iPSCs) of Miller-Dieker syndrome, a severe form of lissencephaly caused by heterozygosity of more than 20 genes including PAFAH1B1, demonstrated a prolongation of mitotic division time of oRG progenitors but not ventricular zone radial glial (vRG) progenitors (Bershteyn et al., 2017).