LIS1/PAFAH1B1-associated lissencephaly includes classical lissencephaly sequence, Subcortical Band Heterotopia (SBH) and Miller-Dieker syndrome (MDS). Lissencephaly (LIS) and SBH comprise the ‘agyria-pachygyria-band’ spectrum of cortical malformations that are caused by deficient neuronal migration during embryogenesis. LIS is characterized by absent (agyria) or decreased (pachygyria) convolutions, cortical thickening and a smooth cerebral surface. SBH is a related disorder in which there are bilateral bands of grey matter interposed in the white matter, between the cortex and the lateral ventricles.
LIS1/PAFAH1B1-associated LIS/SBH is inherited in an autosomal dominant manner, although almost all deletions and intragenic pathogenic variants reported to date have been de novo with very rare exceptions. Classical lissencephaly is rare, with a prevalence of about 12 per 1.000.000 births.