PAFAH1B1 and lissencephaly spectrum disorders: LIS1 mutations in humans cause a “smooth brain” malformation called lissencephaly (LIS) characterized by severe cognitive and motor impairments and worsening epilepsy, leading to early mortality (Dobyns et al., 1993; Sapir et al., 1999; Gleeson, 2000; Sicca et al., 2003; Saillour et al., 2009; Reiner and Sapir, 2013; Dobyns and Das, 2014; Herbst et al., 2016).