<unk>  (MLIS) is a rare congenital brain disorder that combines severe microcephaly (small head) with lissencephaly (smooth brain surface due to absent sulci and gyri).<unk>  is a heterogeneous disorder, i.e. it has many different causes and a variable clinical course.<unk>  is a malformation of cortical development (MCD) that occurs due to failure of neuronal migration between the third and fifth month of gestation as well as stem cell population abnormalities. Numerous genes have been found to be associated with<unk> , however, the pathophysiology is still not completely understood. The combination of lissencephaly with severe congenital microcephaly is designated as<unk>  only when the cortex is abnormally thick. If such combination exists with a normal cortical thickness (2.5 to 3 mm), it is known as "microcephaly with simplified gyral pattern" (MSGP). Both MLIS and MSGP have a much more severe clinical course than microcephaly alone. They are inherited in autosomal recessive manner. Prior to 2000, the term<unk> " was used to designate both MLIS and MSGP.
Microlissencephaly
Microhydranencephaly
Schizencephaly
Hemihydranencephaly
Lissencephaly
Holoprosencephaly
Hydranencephaly
Megalencephaly