<unk>  is one of five subtypes of lissencephaly.<unk> , in turn, can be subclassified based on imaging and clinical picture into 4 types: MLIS1<unk>  Type A or Norman-Roberts syndrome (NRS): a<unk>  with thick cortex without infratentorial anomalies. Other clinical features may include: a bitemporal narrowing, a broad nasal root. There is postnatal growth retardation, severe mental retardation associated with pyramidal spasticity and epilepsy. This entity could be identical to "lissencephaly with cerebellar hypoplasia type B" (LCHb), and therefore linked to mutations in RELN gene. MLIS2<unk>  Type B or Barth<unk>  syndrome: is a<unk>  with thick cortex, severe cerebellar and brainstem hypoplasia. The Barth-type of MLIS is the most severe of all the known lissencephaly syndromes. This phenotype consists of polyhydramnios (probably due to poor fetal swallowing), severe congenital microcephaly, weak respiratory effort, and survival for only a few hours or days. Barth described two siblings with this type as having a very low brainweight, wide ventricles, a very thin neopallium, absent corpus callosum and absent olfactory nerve. MLIS3<unk>  with intermediate cortex and abrupt anteroposterior gradient MLIS4<unk>  with mildly to moderately thick (6–8 mm) cortex, callosal agenesis
Microlissencephaly
Microhydranencephaly
Schizencephaly
Hemihydranencephaly
Lissencephaly
Holoprosencephaly
Hydranencephaly
Megalencephaly