Skip to
  1. Homepage
  2. Rare diseases
  3. Search
Simple search

Simple search

*
(*) mandatory field





 

Other search option(s)

Lissencephaly

ORPHA48471
Synonym(s) -
Prevalence -
Inheritance -
Age of onset Infancy
Neonatal
ICD-10
  • Q04.3
OMIM -
UMLS
  • C0266463
MeSH
  • D054082
MedDRA
  • 10048911

Summary

The term lissencephaly covers a group of rare malformations sharing the common feature of anomalies in the appearance of brain convolutions (characterised by simplification or absence of folding) associated with abnormal organisation of the cortical layers as a result of neuronal migration defects during embryogenesis. Children with lissencephaly have feeding and swallowing problems, muscle tone anomalies (early hypotonia and subsequently limb hypertonia), seizures (in particular, infantile spasms) and severe psychomotor retardation. Multiple forms of lissencephaly have been described and their current classification is based on the associated malformations and underlying aetiology. Two large groups can be distinguished: classical lissencephaly (and its variants) and cobblestone lissencephaly. In classical lissencephaly (or type I), the cortex appears thickened, with four more or less disorganised layers rather than six normal layers. In the variants of classical lissencephaly, extra-cortical anomalies are also present (total or subtotal agenesis of the corpus callosum and/or cerebellar hypoplasia). The classical lissencephalies and the variant forms can be further divided into several subgroups. Four forms can be distinguished on the basis of their genetic aetiology: anomalies in the LIS1 gene (isolated lissencephaly and Miller-Dieker syndrome, see these terms), anomalies in the TUBA3 and DCX genes, and lissencephalies caused by mutations in the ARX gene (X-linked lissencephaly with agenesis of the corpus callosum (XLAG) syndrome; see this term). The incidence of all forms of type I lissencephaly is around 1 in 100,000 births. In addition to these four entities, isolated lissencephalies without a known genetic defect, lissencephalies with severe microcephaly (microlissencephaly) and lissencephalies associated with polymalformative syndromes are also included in the group of classical lissencephalies. Cobblestone lissencephaly (formally referred to as type II) is present in three entities: the Walker-Warburg, Fukuyama and MEB (Muscle-Eye-Brain) syndromes (see these terms). It is characterised by global disorganisation of cerebral organogenesis with an uneven cortical surface (with a pebbled or cobblestone appearance). Microscopic examination reveals total disorganisation of the cortex and the absence of any distinguishable layers. Management is symptomatic only (swallowing problems require adapted feeding to prevent food aspiration, articular and respiratory physiotherapy to prevent orthopaedic problems resulting from hyptonia, and treatment of gastrooesophageal reflux). The epilepsy is often resistant to treatment. The encephalopathy associated with lissencephaly is often very severe and affected children are completely dependent on their carer.

Expert reviewer(s)

  • Pr Alain VERLOES

(*) Required fields.

Attention: Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.


Captcha image

Detailed information

Review article
  • FR (2007,pdf)
Clinical genetics review
  • EN (2011)
Get Acrobat Reader
The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.