PPP4C and lissencephaly spectrum disorders: Cortical disruptions that derive from mutations in genes such as NDE1, LIS1, PP4c, WDR62, CENPE, TCOF1, AGS3, VANGL2 and HTT, are classified as micro- or macro-cephaly, and/or cortical disorganization and abnormal cortical architecture, lissencephaly and simplified gyral patterns.