scholarly journals Insights from spatial measures of intolerance to identify pathogenic variants in developmental and epileptic encephalopathies

2021 ◽  
Author(s):  
Michael Silk ◽  
Alex De Sá ◽  
Moshe Olshansky ◽  
David Benjamin Ascher
Keyword(s):  
Early Onset ◽  
In Silico ◽  
Epileptic Encephalopathy ◽  
Disease Heterogeneity ◽  
Epileptic Encephalopathies ◽  
Pathogenic Variants ◽  
Whole Exome ◽  
Spatial Measures ◽  
Number Of Genes

Developmental and epileptic encephalopathies (DEEs) are a group of epilepsies with early onset and severe symptoms that sometimes lead to death. While a number of genes have been successfully implicated, it remains challenging to identify causative mutations within these genes from the background variation present in all individuals due to disease heterogeneity. Our ability to detect likely pathogenic variants has continued to improve as in silico predictors of deleteriousness have advanced. We investigate their use in prioritising likely pathogenic variants in epileptic encephalopathy patient whole exome sequences and show that the inclusion of structure-based predictors of intolerance improve upon previous attempts to demonstrate enrichment within epilepsy genes.

scholarly journals Loss-of-function variants in DNM1 cause a specific form of developmental and epileptic encephalopathy only in biallelic state

2021 ◽  
pp. jmedgenet-2021-107769
Author(s):  
Gökhan Yigit ◽  
Ruth Sheffer ◽  
Muhannad Daana ◽  
Yun Li ◽  
Emrah Kaygusuz ◽  
...  
Keyword(s):  
Neurological Disorders ◽  
Clinical Symptoms ◽  
Epileptic Encephalopathy ◽  
Specific Form ◽  
Loss Of Function ◽  
Epileptic Encephalopathies ◽  
Pathogenic Variants ◽  
Whole Exome ◽  
Heterozygous Carriers ◽  
Refractory Seizures

BackgroundDevelopmental and epileptic encephalopathies (DEEs) represent a group of severe neurological disorders characterised by an onset of refractory seizures during infancy or early childhood accompanied by psychomotor developmental delay or regression. DEEs are genetically heterogeneous with, to date, more than 80 different genetic subtypes including DEE31 caused by heterozygous missense variants in DNM1.MethodsWe performed a detailed clinical characterisation of two unrelated patients with DEE and used whole-exome sequencing to identify causative variants in these individuals. The identified variants were tested for cosegregation in the respective families.ResultsWe excluded pathogenic variants in known, DEE-associated genes. We identified homozygous nonsense variants, c.97C>T; p.(Gln33*) in family 1 and c.850C>T; p.(Gln284*) in family 2, in the DNM1 gene, indicating that biallelic, loss-of-function pathogenic variants in DNM1 cause DEE.ConclusionOur finding that homozygous, loss-of-function variants in DNM1 cause DEE expands the spectrum of pathogenic variants in DNM1. All parents who were heterozygous carriers of the identified loss-of-function variants were healthy and did not show any clinical symptoms, indicating that the type of mutation in DNM1 determines the pattern of inheritance.

RHOBTB2 p.Arg511Trp Mutation in Early Infantile Epileptic Encephalopathy-64: Review and Case Report

2021 ◽  
Author(s):  
J Fonseca ◽  
C Melo ◽  
C Ferreira ◽  
M Sampaio ◽  
R Sousa ◽  
...  
Keyword(s):  
Case Report ◽  
Intellectual Disability ◽  
Status Epilepticus ◽  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Epileptic Encephalopathy ◽  
Btb Domain ◽  
Pathogenic Variants ◽  
Severe Intellectual Disability ◽  
Whole Exome

AbstractEarly infantile epileptic encephalopathy-64 (EIEE 64), also called RHOBTB2-related developmental and epileptic encephalopathy (DEE), is caused by heterozygous pathogenic variants (EIEE 64; MIM#618004) in the Rho-related BTB domain-containing protein 2 (RHOBTB2) gene. To date, only 13 cases with RHOBTB2-related DEE have been reported. We add to the literature the 14th case of EIEE 64, identified by whole exome sequencing, caused by a heterozygous pathogenic variant in RHOBTB2 (c.1531C > T), p.Arg511Trp. This additional case supports the main features of RHOBTB2-related DEE: infantile-onset seizures, severe intellectual disability, impaired motor functions, postnatal microcephaly, recurrent status epilepticus, and hemiparesis after seizures.

scholarly journals A Novel Heterozygous Missense Variant in YWHAG Gene Cause Early-Onset Epilepsy in a Chinese Family

2020 ◽  
Author(s):  
Zhi Yi ◽  
Zhenfeng Song ◽  
Jiao Xue ◽  
Chengqing Yang ◽  
Fei Li ◽  
...  
Keyword(s):  
Early Onset ◽  
Seizure Control ◽  
De Novo ◽  
Missense Variant ◽  
Epileptic Encephalopathy ◽  
Chinese Family ◽  
Gene Variants ◽  
Case Presentation ◽  
Epileptic Encephalopathies ◽  
Refractory Seizures

Abstract Background: Developmental and epileptic encephalopathies (DEE) are a heterogeneous group of severe disorders which are characterized by early-onset, refractory seizures and developmental slowing or regression. Genetic variations are significant causes for them. De novo variants in an increasing number of candidate genes have been found to be causal. YWHAG gene variants have been reported to cause developmental and epileptic encephalopathy 56 (DEE56). Case presentation: Here, we report a novel heterozygous missense variant c.170G>A (p.R57H) in YWHAG gene cause early-onset epilepsy in a Chinese family. Both the proband and his mother exhibit early onset seizures, intellectual disability, developmental delay. While the proband achieve seizure control with sodium valproate, his mother's seizures were not well controlled. Conclusions: Our report further confirming the haploinsufficiency of YWHAG results in developmental and epileptic encephalopathies.

STXBP1 encephalopathy

Neurology ◽  
2019 ◽  
Vol 93 (3) ◽  
pp. 114-123 ◽  
Author(s):  
Vanessa Lanoue ◽  
Ye Jin Chai ◽  
Julie Z. Brouillet ◽  
Sarah Weckhuysen ◽  
Elizabeth E. Palmer ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Neural Development ◽  
Early Onset ◽  
De Novo ◽  
Basic Research ◽  
Autism Spectrum ◽  
Epileptic Encephalopathy ◽  
Severe Form ◽  
Pathogenic Variants ◽  
Extrapyramidal Features

De novo pathogenic variants in STXBP1 encoding syntaxin1-binding protein (STXBP1, also known as Munc18-1) lead to a range of early-onset neurocognitive conditions, most commonly early infantile epileptic encephalopathy type 4 (EIEE4, also called STXBP1 encephalopathy), a severe form of epilepsy associated with developmental delay/intellectual disability. Other neurologic features include autism spectrum disorder and movement disorders. The progression of neurologic symptoms has been reported in a few older affected individuals, with the appearance of extrapyramidal features, reminiscent of early onset parkinsonism. Understanding the pathologic process is critical to improving therapies, as currently available antiepileptic drugs have shown limited success in controlling seizures in EIEE4 and there is no precision medication approach for the other neurologic features of the disorder. Basic research shows that genetic knockout of STXBP1 or other presynaptic proteins of the exocytic machinery leads to widespread perinatal neurodegeneration. The mechanism that regulates this effect is under scrutiny but shares intriguing hallmarks with classical neurodegenerative diseases, albeit appearing early during brain development. Most critically, recent evidence has revealed that STXBP1 controls the self-replicating aggregation of α-synuclein, a presynaptic protein involved in various neurodegenerative diseases that are collectively known as synucleinopathies, including Parkinson disease. In this review, we examine the tantalizing link among STXBP1 function, EIEE, and the neurodegenerative synucleinopathies, and suggest that neural development in EIEE could be further affected by concurrent synucleinopathic mechanisms.

scholarly journals Genomic Investigation of Infantile and Childhood Epileptic Encephalopathies in Kazakhstan: An Urgent Priority

2021 ◽  
Vol 12 ◽  
Author(s):  
Altynshash Jaxybayeva ◽  
Alissa Nauryzbayeva ◽  
Assem Khamzina ◽  
Meruert Takhanova ◽  
Assel Abilhadirova ◽  
...  
Keyword(s):  
Genetic Testing ◽  
Intellectual Development ◽  
Structural Changes ◽  
Communication Disorders ◽  
Epileptic Encephalopathy ◽  
Epileptic Encephalopathies ◽  
Pathogenic Variants ◽  
Genetic Epilepsies ◽  
First Year Of Life ◽  
Genetically Determined

Objectives: Infantile and childhood epileptic encephalopathies are a group of severe epilepsies that begin within the first year of life and often portend increased morbidity. Many of them are genetically determined. The medical strategy for their management depends on the genetic cause. There are no facilities for genetic testing of children in Kazakhstan but we have a collection of data with already defined genes responsible for clinical presentations.Methods: We analyzed children with epileptic encephalopathies that began in the first 3 years of life and were accompanied by a delay/arrest of intellectual development, in the absence of structural changes in the brain. Such patients were recommended to undergo genetic testing using epileptic genetic panels in laboratories in different countries.Results: We observed 350 infants with clinical presentation of epileptic encephalopathies. 4.3% of them followed our recommendations and underwent genetic testing privately. In total 12/15 children became eligible for targeted treatment, 3/15 were likely to have non-epileptic stereotypies/movements, 2/15 were unlikely to respond to any therapy and all had a high chance of intellectual disability, behavioral and social communication disorders.Conclusion: The genetic results of 15/350 (4.3% of patients) have demonstrated the potential and enormous impact from gene panel analysis in management of epileptic encephalopathy. Availability of genetic testing within the country will improve management of children with genetic epilepsies and help to create a local database of pathogenic variants.

scholarly journals De novo SCN8A and inherited rare CACNA1H variants associated with severe developmental and epileptic encephalopathy

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Robin N. Stringer ◽  
Bohumila Jurkovicova-Tarabova ◽  
Ivana A. Souza ◽  
Judy Ibrahim ◽  
Tomas Vacik ◽  
...  
Keyword(s):  
Ion Channel ◽  
De Novo ◽  
Epileptic Encephalopathy ◽  
Gene Encoding ◽  
Epileptic Encephalopathies ◽  
Voltage Gated ◽  
Voltage Gated Calcium Channels ◽  
Whole Exome ◽  
Heterozygous Variant

AbstractDevelopmental and epileptic encephalopathies (DEEs) are a group of severe epilepsies that are characterized by seizures and developmental delay. DEEs are primarily attributed to genetic causes and an increasing number of cases have been correlated with variants in ion channel genes. In this study, we report a child with an early severe DEE. Whole exome sequencing showed a de novo heterozygous variant (c.4873–4881 duplication) in the SCN8A gene and an inherited heterozygous variant (c.952G > A) in the CACNA1H gene encoding for Nav1.6 voltage-gated sodium and Cav3.2 voltage-gated calcium channels, respectively. In vitro functional analysis of human Nav1.6 and Cav3.2 channel variants revealed mild but significant alterations of their gating properties that were in general consistent with a gain- and loss-of-channel function, respectively. Although additional studies will be required to confirm the actual pathogenic involvement of SCN8A and CACNA1H, these findings add to the notion that rare ion channel variants may contribute to the etiology of DEEs.

scholarly journals The role of recessive inheritance in early-onset epileptic encephalopathies: a combined whole-exome sequencing and copy number study

2018 ◽  
Vol 27 (3) ◽  
pp. 408-421 ◽  
Author(s):  
Sorina M. Papuc ◽  
Lucia Abela ◽  
Katharina Steindl ◽  
Anaïs Begemann ◽  
Thomas L. Simmons ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Early Onset ◽  
Copy Number ◽  
Recessive Inheritance ◽  
Epileptic Encephalopathies ◽  
Whole Exome

scholarly journals Defining and expanding the phenotype of QARS-associated developmental epileptic encephalopathy

2019 ◽  
Vol 5 (6) ◽  
pp. e373
Author(s):  
Katrine M. Johannesen ◽  
Diana Mitter ◽  
Robert Janowski ◽  
Christian Roth ◽  
Joseph Toulouse ◽  
...  
Keyword(s):  
Developmental Delay ◽  
Early Onset ◽  
Epileptic Encephalopathy ◽  
Small Subset ◽  
Mri Findings ◽  
Pharmacoresistant Epilepsy ◽  
Pathogenic Variants ◽  
Cranial Mri ◽  
Delayed Myelination

ObjectiveThe study is aimed at widening the clinical and genetic spectrum and at assessing genotype-phenotype associations in QARS encephalopathy.MethodsThrough diagnostic gene panel screening in an epilepsy cohort, and recruiting through GeneMatcher and our international network, we collected 10 patients with biallelic QARS variants. In addition, we collected data on 12 patients described in the literature to further delineate the associated phenotype in a total cohort of 22 patients. Computer modeling was used to assess changes on protein folding.ResultsBiallelic pathogenic variants in QARS cause a triad of progressive microcephaly, moderate to severe developmental delay, and early-onset epilepsy. Microcephaly was present at birth in 65%, and in all patients at follow-up. Moderate (14%) or severe (73%) developmental delay was characteristic, with no achievement of sitting (85%), walking (86%), or talking (90%). Additional features included irritability (91%), hypertonia/spasticity (75%), hypotonia (83%), stereotypic movements (75%), and short stature (56%). Seventy-nine percent had pharmacoresistant epilepsy with mainly neonatal onset. Characteristic cranial MRI findings include early-onset progressive atrophy of cerebral cortex (89%) and cerebellum (61%), enlargement of ventricles (95%), and age-dependent delayed myelination (88%). A small subset of patients displayed a less severe phenotype.ConclusionsThese data revealed first genotype-phenotype associations and may serve for improved interpretation of new QARS variants and well-founded genetic counseling.

scholarly journals Case Report: Causative De novo Variants of KCNT2 for Developmental and Epileptic Encephalopathy

2021 ◽  
Vol 12 ◽  
Author(s):  
Pan Gong ◽  
Xianru Jiao ◽  
Dan Yu ◽  
Zhixian Yang
Keyword(s):  
De Novo ◽  
Gene Mutations ◽  
Epileptic Encephalopathy ◽  
Infantile Spasms ◽  
Loss Of Function ◽  
Gain Of Function ◽  
Dysmorphic Features ◽  
Pathogenic Variants ◽  
Ohtahara Syndrome ◽  
Whole Exome

Objective:KCNT2 gene mutations had been described to cause developmental and epileptic encephalopathies (DEEs). In this study, we presented the detailed clinical features and genetic analysis of two unrelated patients carrying two de novo variants in KCNT2 and reviewed eight different cases available in publications.Methods: Likely pathogenic variants were identified by whole exome sequencing; clinical data of the patients were retrospectively collected and analyzed.Results: Our two unrelated patients were diagnosed with Ohtahara syndrome followed by infantile spasms (IS) and possibly the epilepsy of infancy with migrating focal seizures (EIMFS), respectively. They both manifested dysmorphic features with hirsute arms, thick hair, prominent eyebrows, long and thick eyelashes, a broad nasal tip, and short and smooth philtrum. In the eight patients reported previously, two was diagnosed with IS carrying a ‘change-of-function' mutation and a gain-of-function mutation, respectively, two with EIMFS-like carrying a gain-of-function mutation and a loss-of-function mutation, respectively, one with EIMFS carrying a loss-of-function mutation, three with DEE without functional analysis. Among them, two patients with gain-of-function mutations both exhibited dysmorphic features and presented epilepsy phenotype, which was similar to our patients.Conclusion: Overall, the most common phenotypes associated with KCNT2 mutation were IS and EIMFS. Epilepsy phenotype associated with gain- and loss-of-function mutations could overlap. Additional KCNT2 cases will help to make genotype-phenotype correlations clearer.

scholarly journals Clinical and genetic characteristics of the early 66th type epileptic encephalopathy (literature review and own observation)

2020 ◽  
Vol 10 (1) ◽  
pp. 88-92
Author(s):  
T. V. Markova ◽  
A. O. Borovikov ◽  
E. R. Lozier ◽  
A. A. Isaev ◽  
V. S. Kaimonov ◽  
...  
Keyword(s):  
Nucleotide Sequence ◽  
Literature Review ◽  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Male Patient ◽  
Epileptic Encephalopathy ◽  
Genetic Characteristics ◽  
Epileptic Encephalopathies ◽  
Whole Exome ◽  
Heterozygous Variant

Early epileptic encephalopathy-66 was first diagnosed in a male patient from Russia using whole-exome sequencing. Early epileptic encephalopathy- 66 is a unique disorder in the group of early epileptic encephalopathies. The same recurrent heterozygous variant of the nucleotide sequence was found in all known patients, but the severity of seizures and dysmorphic signs significantly vary between patients. The current study of a recurrent pathogenic variant in PACS2 gene expands the phenotype spectrum of early epileptic encephalopathy-66 and will improve the management of patients with that disorder in Russia in the future.

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