Lissencephaly 1 (LIS1)

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MedlinePlus Genetics: ⁴² Isolated lissencephaly sequence (ILS) is a condition that affects brain development before birth. Normally, the cells that make up the exterior of the brain (cerebral cortex) are well-organized, multi-layered, and arranged into many folds and grooves (gyri). In people with ILS, the cells of the cerebral cortex are disorganized, and the brain surface is abnormally smooth with an absence (agyria) or reduction (pachygyria) of folds and grooves. In most cases, these abnormalities impair brain growth, causing the brain to be smaller than normal (microcephaly). This underdevelopment of the brain causes severe intellectual disability, delayed development, and recurrent seizures (epilepsy) in individuals with ILS.More than 90 percent of individuals with ILS develop epilepsy, often within the first year of life. Up to 80 percent of infants with ILS have a type of seizure called infantile spasms, these seizures can be severe enough to cause brain dysfunction (epileptic encephalopathy). After the first months of life, most children with ILS develop a variety of seizure types, including persisting infantile spasms, short periods of loss of consciousness (absence seizures); sudden episodes of weak muscle tone (drop attacks); rapid, uncontrolled muscle jerks (myoclonic seizures); and episodes of muscle rigidity, convulsions, and loss of consciousness (tonic-clonic seizures).Infants with ILS may have poor muscle tone (hypotonia) and difficulty feeding, which leads to poor growth overall. Hypotonia also affects the muscles used for breathing, which often causes breathing problems that can lead to a life-threatening bacterial lung infection known as aspiration pneumonia. Children with ILS often develop muscle stiffness (spasticity) in their arms and legs and an abnormal side-to-side curvature of the spine (scoliosis). Rarely, the muscle stiffness will progress to paralysis (spastic paraplegia). Individuals with ILS cannot walk and rarely crawl. Most children with ILS do not develop communication skills.

MalaCards based summary: Lissencephaly 1, also known as lis1, is related to lissencephaly, x-linked, 1 and lissencephaly 10. An important gene associated with Lissencephaly 1 is PAFAH1B1 (Platelet Activating Factor Acetylhydrolase 1b Regulatory Subunit 1), and among its related pathways/superpathways are Cell Cycle Checkpoints and Neuroscience. The drugs Prednisolone phosphate and Prednisolone acetate have been mentioned in the context of this disorder. Affiliated tissues include cortex, brain and lung, and related phenotypes are infantile spasms and thick cerebral cortex

OMIM®: ⁵⁷ Lissencephaly (LIS), literally meaning smooth brain, is characterized by smooth or nearly smooth cerebral surface and a paucity of gyral and sulcal development, encompassing a spectrum of brain surface malformations ranging from complete agyria to subcortical band heterotopia (SBH). Classic lissencephaly is associated with an abnormally thick cortex, reduced or abnormal lamination, and diffuse neuronal heterotopia. SBH consists of circumferential bands of heterotopic neurons located just beneath the cortex and separated from it by a thin band of white matter. SBH represents the less severe end of the lissencephaly spectrum of malformations (Pilz et al., 1999, summary by Kato and Dobyns, 2003). Agyria, i.e., brain without convolutions or gyri, was considered a rare malformation until recent progress in neuroradiology (Bordarier et al., 1986). With this technical advantage, a number of lissencephaly syndromes have been distinguished. Classic lissencephaly (formerly type I) is a brain malformation caused by abnormal neuronal migration at 9 to 13 weeks' gestation, resulting in a spectrum of agyria, mixed agyria/pachygyria, and pachygyria. It is characterized by an abnormally thick and poorly organized cortex with 4 primitive layers, diffuse neuronal heterotopia, enlarged and dysmorphic ventricles, and often hypoplasia of the corpus callosum (Lo Nigro et al., 1997). Kato and Dobyns (2003) presented a classification system for neuronal migration disorders based on brain imaging findings and molecular analysis. The authors also reviewed the contributions and interactions of the 5 genes then known to cause human lissencephaly: LIS1 (PAFAH1B1), 14-3-3-epsilon (YWHAE), DCX, RELN, and ARX. (607432) (Updated 08-Dec-2022)

GARD: ¹⁹ PAFAH1B1-associated lissencephaly includes Miller-Dieker syndrome (MDS), isolated lissencephaly sequence (ILS), and (rarely) subcortical band heterotopia (SBH). Lissencephaly and SBH are cortical malformations caused by deficient neuronal migration during embryogenesis. Lissencephaly refers to a \"smooth brain\" with absent gyri (agyria) or abnormally wide gyri (pachygyria). SBH refers to a band of heterotopic gray matter located just beneath the cortex and separated from it by a thin zone of normal white matter. MDS is characterized by lissencephaly, typical facial features, and severe neurologic abnormalities. ILS is characterized by lissencephaly and its direct sequelae: developmental delay, intellectual disability, and seizures.

UniProtKB/Swiss-Prot ⁷³ Lissencephaly 1: A classical lissencephaly. It is characterized by agyria or pachygyria and disorganization of the clear neuronal lamination of normal six- layered cortex. The cortex is abnormally thick and poorly organized with 4 primitive layers. Associated with enlarged and dysmorphic ventricles and often hypoplasia of the corpus callosum.

Subcortical band heterotopia: SBH is a mild brain malformation of the lissencephaly spectrum. It is characterized by bilateral and symmetric plates or bands of gray matter found in the central white matter between the cortex and cerebral ventricles, cerebral convolutions usually appearing normal.

Orphanet: ⁵⁸ Lissencephaly due to LIS1 mutation is a cerebral malformation with epilepsy characterized predominantly by posterior isolated lissencephaly with developmental delay, intellectual disability and epilepsy that usually evolves from West syndrome to Lennox-Gastaut syndrome. Additional features include muscular hypotonia, acquired microcephaly, failure to thrive and poor control of airways leading to aspiration pneumonia.

Disease Ontology: ¹¹ A lissencephaly characterized by an abnormally thick cortex, reduced or abnormal lamination, and diffuse neuronal heterotopia that has material basis in mutation heterozygous in PAFAH1B1 on chromosome 17p13.3.

Wikipedia: ⁷⁵ Lissencephaly (/ˌlɪs.ɛnˈsɛf.əl.i/, meaning "smooth brain") is a set of rare brain disorders whereby the... more...

Clinical features from OMIM®:

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