PAFAH1B1 and Lissencephaly: Consequently, Pafah1b1 haploinsufficiency results in classical, or Type I, lissencephaly (‘smooth brain’), a rare neurodevelopmental disorder characterized in humans by brain malformation, intellectual disability, motor impairment, and drug-resistant epilepsy (Kato, 2003; Di Donato et al., 2017).