Lissencephaly 1 (LIS1)

What is Lissencephaly 1 (LIS1)?

Also known as Classic Lissencephaly this rare disease is a brain malformation syndrome that may by itself be considered as standalone syndrome, or it may also be one of the symptoms of other syndromes such as Miller-Dieker.

This brain malformation is known as agyria or pachygyria (absent or incomplete development) of the brain- specifically concerning the ridge on the cerebral cortex of the brain. This means instead of presenting with folds and ridges, the brain appears smooth.

This syndrome is also known as:
Double cortex syndrome Lissencephaly Sequence, Isolated; Ils Lissencephaly, Classic Subcortical laminar heterotopia X-linked isolated lissencephaly XSCLH/LIS

What gene changes cause Lissencephaly 1 (LIS1)?

The genetic changes responsible for the syndrome include mutations in the following genes: PAFAH1B1, RELN, TUBA1A, NDE1, KATNB1, CDK5, ARX and DCX among others. There is still more research to be done in fully understanding the causes of this condition.

The exact mode of inheritance was unknown at the time this entry was recorded.

Alongside the genetic causes of the syndrome it may also be the result of viral infections, or restricted blood flow to the brain during its development.

What are the main symptoms of Lissencephaly 1 (LIS1)?

Those individuals affected by isolated Lissencephaly, as in just the brain malformation and no other syndrome, have symptoms such as a small head, small jaw, and indentation of the temples of the head.

Other related symptoms, usually present at birth and in infancy, include issues with feeding, failure to thrive, low muscle tone in early infancy followed by an increased muscle tone in later infancy, and delayed or impacted motor skills.

Possible clinical traits/features:
Gray matter heterotopia, Global developmental delay, Hypoplasia of the brainstem, Muscular hypotonia of the trunk, Lissencephaly, Intellectual disability, Postnatal microcephaly, Ventriculomegaly, Pachygyria, Seizure, Spastic tetraparesis, Sporadic, Variable expressivity, Abnormality of the cerebral white matter, Cerebellar hypoplasia

How does someone get tested for Lissencephaly 1 (LIS1)?

The initial testing for Lissencephaly 1 syndrome can begin with facial analysis screening, through the FDNA Telehealth telegenetics platform, which can identify the key markers of the syndrome and outline the need for further testing. A consultation with a genetic counselor and then a geneticist will follow.

Based on this clinical consultation with a geneticist, the different options for genetic testing will be shared and consent will be sought for further testing.

Medical information on Lissencephaly 1 (LIS1)

De novo mutations in LIS1 (PAFAH1B1) cause Miller-Dieker syndrome (lissencephaly with dysmorphic features), isolated lissencephaly sequence or subcortical band heterotopia. Intellectual disability, seizures and severe neurological abnormalities are characteristic features.

De Vita et al. (2018) reported a mother and son carrying a missense LIS1 variant who presented with focal epilepsy, mild cognitive impairment, and pachygyria.

* This information is courtesy of the L M D.
If you find a mistake or would like to contribute additional information, please email us at: [email protected]

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