Lissencephaly
Neuronal migration describes the journey the nerve cells make
from the inner to the outer surface of the brain during development
to form the cortex (grey matter). Lissencephaly is a neuronal
migration disorder, and the name 'lissencephaly' is derived from
the Greek words 'lissos' - smooth and 'encephalos' - brain. The
convolutions (folds) of the brain can be absent, giving the surface
the 'smooth' appearance. Two major types are distinguished:
classical lissencephaly (also known as type I) and cobblestone
lissencephaly (also known as type II). Several syndromes are
recognised with each type. General problems include developmental
delay, seizures, and feeding difficulties. Life expectancy is often
reduced.
Classical lissencephaly can be associated with
agyria (absent convolutions) or pachygyria (reduced and thickened
convolutions) of the brain and subcortical band heterotopia (SBH) -
a band of nerve cells located in the white matter instead of the
grey matter. Syndromes with classical lissencephaly include
Miller-Dieker syndrome (MDS) associated with distinct facial
features and occasional heart or abdominal defects, and Isolated
Lissencephaly Sequence (ILS), where associated features are
uncommon.
Cobblestone lissencephaly syndromes include
Walker-Warburg syndrome (WWS), muscle-eye-brain disease (MEB) and
Fukuyama congenital muscular dystrophy (FCMD). These conditions are
also associated with developmental eye problems and muscular
dystrophy.
Credits
Medical text written September 2001 by Dr D Pilz, last updated
October 2007 by Dr D Pilz, Consultant Clinical Geneticist,
Institute of Medical Genetics, University Hospital of Wales,
Cardiff, UK.
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mother talks how Polymicrogyria affects her daughter and family
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Neuronal migration disorders (NMDs) are a group
of birth defects caused by the abnormal migration of neurons in the
developing brain and nervous system. In this podcast a mothertalks
about how the condition affects her daughter.
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