PAFAH1B1 and lissencephaly spectrum disorders: Haploinsufficiency of LIS1 (official symbol PAFAH1b1, for platelet-activating factor (PAF) acetylhydrolase isoform 1b subunit 1) causes lissencephaly, a severe human developmental brain disorder manifested by a smooth cerebral surface and disorganized cortical layers due to incomplete neuronal migration [21], [22].