PAFAH1B1 and lissencephaly spectrum disorders: However, the primary genetic drivers of lissencephaly are missense mutations in, or truncations and deletions of the LIS1 gene (lissencephaly-1) (Reiner et al., 1993), which was confirmed to be required for neuronal migration in a mouse model (Hirotsune et al., 1998), and in fly embryos (Swan et al., 1999).