lissencephaly with cerebellar hypoplasia LCH: microcephaly + lissencephaly type1/2 + varous cerebellar hypoplasia. TUBA1A, RELN, LIS1, DCX, VLDLR

X-linked lissencephaly XLIS: boys are severely affected, die within days of birth, girls have mild phenotype. ARX

under migration : neurons are arrested in their migration prior to their arrival in the appropriate cortical laminae (~12-13 gw)

over migration: neurons beyond their designated laminae and into the subarachnoid space - cobblestone appearance

small brain, tortuous surface vessels, 4 layered cortexm, ectopic olivary nuclei, abnormally convoluted dentate nuclei

fetal MRI: very thick smooth cprtex, shallow sylvian fissures, figure 8 shape on axial plane

classic type 1 lissencephaly: no associated other major brain or extracerebral anomalias, callosal agenesis uncommon

Miller-Dieker sy: codeletion of LIS1 and YHAWAE, dysmorphic facial features, digital abnormalities and retinal hypervascularisation

pachygyria: milder form, thickened cortex + abnormally broad gyri - LIS1, congenital CMV encephalopathy

girls: subcortical band heterotopia - thin/thick - localized/diffuse, normal development/seizure/cognitive impairment