Microlissencephaly is a type of lissencephaly characterized by the presence of a severe microcephaly. Prevalence is unknown. They result from an abnormal neuronal proliferation or survival combined to neuronal migration disorders. Two main types of microlissencephalies are recognized: the type A (previously called the Norman-Roberts syndrome with no infratentorial anomalies and the type B (or Barth syndrome), which is associated with a severe hypoplasia of the cerebellum and corpus callosum.
Last update: March 2004