Publications by authors named "Lynette G Sadleir"

59 Publications

Contribution of rare genetic variants to drug response in absence epilepsy.

Epilepsy Res 2021 Feb 4;170:106537. Epub 2021 Jan 4.

Epilepsy Research Centre, Department of Medicine, The University of Melbourne, Austin Health, 245 Burgundy St, Heidelberg, VIC, 3084, Australia; Department of Neurology, Royal Children's Hospital, The University of Melbourne, 50 Flemington Rd, Parkville, VIC, 3052, Australia; Murdoch Children's Research Institute, Royal Children's Hospital, 50 Flemington Rd, Parkville, VIC, 3052, Australia; Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.

Objective: We investigated the possible significance of rare genetic variants to response to valproic acid (VPA) and ethosuximide (ETX) in patients with absence epilepsy. Our primary hypothesis was that rare CACNA1H variants are more frequent in ETX-non-responsive patients compared to ETX-responsive. Our secondary hypothesis was that rare variants in GABA-receptor genes are more frequent in VPA-non-responsive patients compared to VPA-responsive.

Methods: We recruited patients with absence epilepsy treated with both VPA and ETX, and performed whole exome sequencing in order to investigate the potential role of rare variants in CACNA1H, other voltage-gated calcium channel (VGCC) genes, or GABA-receptor genes in predicting response to ETX or VPA.

Results: Sixty-two patients were included; 12 were ETX-responsive, 14 VPA-responsive, and 36 did not have a clear positive response to either medication. We did not find significant enrichment inCACNA1H rare variants in ETX-responsive patients (odds ratio 3.43; 0.43-27.65; p = 0.20), nor was there enrichment for other VGCC genes. No significant enrichment of GABA-receptor gene rare variants was seen for VPA-non-responsive patients versus VPA-responsive. We found enrichment of rare GABA-receptor variants in our absence cohort compared to controls (odds ratio 3.82; 1.68-8.69). There was no difference in frequency of CACNA1H rs61734410 and CACNA1I rs3747178 polymorphisms between ETX-responsive and ETX-non-responsive groups; these polymorphisms have previously been reported to predict lack of response to ETX in absence epilepsy.

Significance: We conclude that if CACNA1H rare variants predict lack of response to ETX, a larger sample is necessary to test this with sufficient power. Increased GABA-receptor gene rare variant frequency in absence epilepsy patients who fail initial anti-seizure therapy suggests subtle GABA receptor dysfunction may contribute to the underlying pathophysiology.
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http://dx.doi.org/10.1016/j.eplepsyres.2020.106537DOI Listing
February 2021

The phenotypic spectrum of X-linked, infantile onset ALG13-related developmental and epileptic encephalopathy.

Epilepsia 2021 Feb 7;62(2):325-334. Epub 2021 Jan 7.

Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany.

Objective: Asparagine-linked glycosylation 13 (ALG13) deficiencies have been repeatedly described in the literature with the clinical phenotype of a developmental and epileptic encephalopathy (DEE). Most cases were females carrying the recurrent ALG13 de novo variant, p.(Asn107Ser), with normal transferrin electrophoresis.

Methods: We delineate the phenotypic spectrum of 38 individuals, 37 girls and one boy, 16 of them novel and 22 published, with the most common pathogenic ALG13 variant p.(Asn107Ser) and additionally report the phenotype of three individuals carrying other likely pathogenic ALG13 variants.

Results: The phenotypic spectrum often comprised pharmacoresistant epilepsy with epileptic spasms, mostly with onset within the first 6 months of life and with spasm persistence in one-half of the cases. Tonic seizures were the most prevalent additional seizure type. Electroencephalography showed hypsarrhythmia and at a later stage of the disease in one-third of all cases paroxysms of fast activity with electrodecrement. ALG13-related DEE was usually associated with severe to profound developmental delay; ambulation was acquired by one-third of the cases, whereas purposeful hand use was sparse or completely absent. Hand stereotypies and dyskinetic movements including dystonia or choreoathetosis were relatively frequent. Verbal communication skills were absent or poor, and eye contact and pursuit were often impaired.

Significance: X-linked ALG13-related DEE usually manifests as West syndrome with severe to profound developmental delay. It is predominantly caused by the recurrent de novo missense variant p.(Asn107Ser). Comprehensive functional studies will be able to prove or disprove an association with congenital disorder of glycosylation.
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http://dx.doi.org/10.1111/epi.16761DOI Listing
February 2021

New insights into the clinical and molecular spectrum of the novel CYFIP2-related neurodevelopmental disorder and impairment of the WRC-mediated actin dynamics.

Genet Med 2020 Nov 5. Epub 2020 Nov 5.

Institute of Medical Genetics, University of Zurich, Schlieren-Zurich, Switzerland.

Purpose: A few de novo missense variants in the cytoplasmic FMRP-interacting protein 2 (CYFIP2) gene have recently been described as a novel cause of severe intellectual disability, seizures, and hypotonia in 18 individuals, with p.Arg87 substitutions in the majority.

Methods: We assembled data from 19 newly identified and all 18 previously published individuals with CYFIP2 variants. By structural modeling and investigation of WAVE-regulatory complex (WRC)-mediated actin polymerization in six patient fibroblast lines we assessed the impact of CYFIP2 variants on the WRC.

Results: Sixteen of 19 individuals harbor two previously described and 11 novel (likely) disease-associated missense variants. We report p.Asp724 as second mutational hotspot (4/19 cases). Genotype-phenotype correlation confirms a consistently severe phenotype in p.Arg87 patients but a more variable phenotype in p.Asp724 and other substitutions. Three individuals with milder phenotypes carry putative loss-of-function variants, which remain of unclear pathogenicity. Structural modeling predicted missense variants to disturb interactions within the WRC or impair CYFIP2 stability. Consistent with its role in WRC-mediated actin polymerization we substantiate aberrant regulation of the actin cytoskeleton in patient fibroblasts.

Conclusion: Our study expands the clinical and molecular spectrum of CYFIP2-related neurodevelopmental disorder and provides evidence for aberrant WRC-mediated actin dynamics as contributing cellular pathomechanism.
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http://dx.doi.org/10.1038/s41436-020-01011-xDOI Listing
November 2020

NEXMIF encephalopathy: an X-linked disorder with male and female phenotypic patterns.

Genet Med 2021 Feb 4;23(2):363-373. Epub 2020 Nov 4.

Epilepsy Research Centre, Department of Medicine, Austin Health, University of Melbourne, Melbourne, VIC, Australia.

Purpose: Pathogenic variants in the X-linked gene NEXMIF (previously KIAA2022) are associated with intellectual disability (ID), autism spectrum disorder, and epilepsy. We aimed to delineate the female and male phenotypic spectrum of NEXMIF encephalopathy.

Methods: Through an international collaboration, we analyzed the phenotypes and genotypes of 87 patients with NEXMIF encephalopathy.

Results: Sixty-three females and 24 males (46 new patients) with NEXMIF encephalopathy were studied, with 30 novel variants. Phenotypic features included developmental delay/ID in 86/87 (99%), seizures in 71/86 (83%) and multiple comorbidities. Generalized seizures predominated including myoclonic seizures and absence seizures (both 46/70, 66%), absence with eyelid myoclonia (17/70, 24%), and atonic seizures (30/70, 43%). Males had more severe developmental impairment; females had epilepsy more frequently, and varied from unaffected to severely affected. All NEXMIF pathogenic variants led to a premature stop codon or were deleterious structural variants. Most arose de novo, although X-linked segregation occurred for both sexes. Somatic mosaicism occurred in two males and a family with suspected parental mosaicism.

Conclusion: NEXMIF encephalopathy is an X-linked, generalized developmental and epileptic encephalopathy characterized by myoclonic-atonic epilepsy overlapping with eyelid myoclonia with absence. Some patients have developmental encephalopathy without epilepsy. Males have more severe developmental impairment. NEXMIF encephalopathy arises due to loss-of-function variants.
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http://dx.doi.org/10.1038/s41436-020-00988-9DOI Listing
February 2021

Are Variants Causing Cardiac Arrhythmia Risk Factors in Sudden Unexpected Death in Epilepsy?

Front Neurol 2020 8;11:925. Epub 2020 Sep 8.

Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia.

Sudden unexpected death in epilepsy (SUDEP) is the most common cause of premature mortality in individuals with epilepsy. Acute and adaptive changes in heart rhythm in epilepsy implicate cardiac dysfunction as a potential pathogenic mechanism in SUDEP. Furthermore, variants in genes associated with Long QT syndrome (LQTS) have been identified in patients with SUDEP. LQTS is a cardiac arrhythmia condition that causes sudden cardiac death with strong similarities to SUDEP. Here, we discuss the possibility of an additive risk of death due to the functional consequences of a pathogenic variant in an LQTS gene interacting with seizure-mediated changes in cardiac function. Extending this general concept, we propose a hypothesis that common variants in LQTS genes, which cause a subtle impact on channel function and would not normally be considered risk factors for cardiac disease, may increase the risk of sudden death when combined with epilepsy. A greater understanding of the interaction between epilepsy, cardiac arrhythmia, and SUDEP will inform our understanding of SUDEP risk and subsequent potential prophylactic treatment.
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http://dx.doi.org/10.3389/fneur.2020.00925DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7505992PMC
September 2020

Developmental and epilepsy spectrum of KCNB1 encephalopathy with long-term outcome.

Epilepsia 2020 11 21;61(11):2461-2473. Epub 2020 Sep 21.

Department of Pediatric Neurology, Reference Center for Rare Epilepsies, Assistance Publique-Hôpitaux de Paris (AP-HP), Necker-Enfants Malades Hospital, Paris, France.

Objective: We aimed to delineate the phenotypic spectrum and long-term outcome of individuals with KCNB1 encephalopathy.

Methods: We collected genetic, clinical, electroencephalographic, and imaging data of individuals with KCNB1 pathogenic variants recruited through an international collaboration, with the support of the family association "KCNB1 France." Patients were classified as having developmental and epileptic encephalopathy (DEE) or developmental encephalopathy (DE). In addition, we reviewed published cases and provided the long-term outcome in patients older than 12 years from our series and from literature.

Results: Our series included 36 patients (21 males, median age = 10 years, range = 1.6 months-34 years). Twenty patients (56%) had DEE with infantile onset seizures (seizure onset = 10 months, range = 10 days-3.5 years), whereas 16 (33%) had DE with late onset epilepsy in 10 (seizure onset = 5 years, range = 18 months-25 years) and without epilepsy in six. Cognitive impairment was more severe in individuals with DEE compared to those with DE. Analysis of 73 individuals with KCNB1 pathogenic variants (36 from our series and 37 published individuals in nine reports) showed developmental delay in all with severe to profound intellectual disability in 67% (n = 41/61) and autistic features in 56% (n = 32/57). Long-term outcome in 22 individuals older than 12 years (14 in our series and eight published individuals) showed poor cognitive, psychiatric, and behavioral outcome. Epilepsy course was variable. Missense variants were associated with more frequent and more severe epilepsy compared to truncating variants.

Significance: Our study describes the phenotypic spectrum of KCNB1 encephalopathy, which varies from severe DEE to DE with or without epilepsy. Although cognitive impairment is worse in patients with DEE, long-term outcome is poor for most and missense variants are associated with more severe epilepsy outcome. Further understanding of disease mechanisms should facilitate the development of targeted therapies, much needed to improve the neurodevelopmental prognosis.
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http://dx.doi.org/10.1111/epi.16679DOI Listing
November 2020

PCDH19 Pathogenic Variants in Males: Expanding the Phenotypic Spectrum.

Adv Exp Med Biol 2020 ;1298:177-187

Adelaide Medical School, the University of Adelaide, Adelaide, SA, Australia.

Protocadherin-19 (PCDH19) pathogenic variants cause an infantile onset epilepsy syndrome called Girls Clustering Epilepsy due to the vast majority of affected individuals being female. This syndromic name was developed to foster early recognition and diagnosis in infancy. It has, however, sparked debate, as, there are rare males with postzygotic somatic, and therefore, mosaic, PCDH19 pathogenic variants with similar clinical features to females. Conversely, "transmitting" males with germline inherited PCDH19 variants are considered asymptomatic. To date, there has been no standardized neuropsychiatric assessment of males with PCDH19 pathogenic variants. Here, we studied 15 males with PCDH19 pathogenic variants (nine mosaic and six transmitting) aged 2 to 70 years. Our families completed a survey including standardized clinical assessments: Social Responsiveness Scale, Strengths and Difficulties Questionnaire, Behavior Rating Inventory of Executive Function, and Dimensional Obsessive-Compulsive Scale. We identified neuropsychiatric abnormalities in two males with germline PCDH19 possibly pathogenic variants. One had a prior history of a severe encephalopathic illness, which may have been unrelated. We also describe a non-penetrant somatic mosaic male with mosaicism confirmed in blood, but not identified in skin fibroblasts. Our data suggest that transmitting hemizygous males are generally unaffected, in contrast to males with postzygotic somatic mosaic variants who show a similar neuropsychiatric profile to females who are naturally mosaic, due to X-chromosome inactivation. The penetrance of PCDH19 pathogenic variants has been estimated to be 80%. Like females, not all mosaic males are affected. From our small sample, we estimate that males with mosaic PCHD19 pathogenic variants have a penetrance of 85%. With these insights into the male phenotypic spectrum of PCDH19 epilepsy, we propose the new term Clustering Epilepsy (CE). Both affected females and males typically present with infantile onset of clusters of seizures.
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http://dx.doi.org/10.1007/5584_2020_574DOI Listing
November 2020

A standardized patient-centered characterization of the phenotypic spectrum of PCDH19 girls clustering epilepsy.

Transl Psychiatry 2020 05 4;10(1):127. Epub 2020 May 4.

Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia.

Protocadherin-19 (PCDH19) pathogenic variants cause an early-onset seizure disorder called girls clustering epilepsy (GCE). GCE is an X-chromosome disorder that affects heterozygous females and mosaic males, however hemizygous ("transmitting") males are spared. We aimed to define the neuropsychiatric profile associated with PCDH19 pathogenic variants and determine if a clinical profile exists for transmitting males. We also examined genotype- and phenotype-phenotype associations. We developed an online PCDH19 survey comprising the following standardized assessments: The Behavior Rating Inventory of Executive Function; the Social Responsiveness Scale, 2nd edition; the Strengths and Difficulties Questionnaire; and the Dimensional Obsessive-Compulsive Scale. Genetic, seizure, and developmental information were also collected. The survey was completed by patients or by caregivers on behalf of patients. Of the 112 individuals represented (15 males), there were 70 unique variants. Thirty-five variants were novel and included a newly identified recurrent variant Ile781Asnfs*3. There were no significant differences in phenotypic outcomes between published and unpublished cases. Seizures occurred in clusters in 94% of individuals, with seizures resolving in 28% at an average age of 17.5 years. Developmental delay prior to seizure onset occurred in 18% of our cohort. Executive dysfunction and autism spectrum disorder (ASD) occurred in approximately 60% of individuals. The ASD profile included features of attention-deficit hyperactivity disorder. In addition, 21% of individuals met criteria for obsessive-compulsive disorder that appeared to be distinct from ASD. There were no phenotypic differences between heterozygous females and mosaic males. We describe a mosaic male and two hemizygous males with atypical clinical profiles. Earlier seizure onset age and increased number of seizures within a cluster were associated with more severe ASD symptoms (p = 0.001), with seizure onset also predictive of executive dysfunction (p = 4.69 × 10) and prosocial behavior (p = 0.040). No clinical profile was observed for transmitting males. This is the first patient-derived standardized assessment of the neuropsychiatric profile of GCE. These phenotypic insights will inform diagnosis, management, and prognostic and genetic counseling.
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http://dx.doi.org/10.1038/s41398-020-0803-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7198503PMC
May 2020

Damaging de novo missense variants in EEF1A2 lead to a developmental and degenerative epileptic-dyskinetic encephalopathy.

Hum Mutat 2020 Jul 6;41(7):1263-1279. Epub 2020 Apr 6.

Barrow Neurological Institute, Department of Neurology, Phoenix Children's Hospital, Phoenix, Arizona.

Heterozygous de novo variants in the eukaryotic elongation factor EEF1A2 have previously been described in association with intellectual disability and epilepsy but never functionally validated. Here we report 14 new individuals with heterozygous EEF1A2 variants. We functionally validate multiple variants as protein-damaging using heterologous expression and complementation analysis. Our findings allow us to confirm multiple variants as pathogenic and broaden the phenotypic spectrum to include dystonia/choreoathetosis, and in some cases a degenerative course with cerebral and cerebellar atrophy. Pathogenic variants appear to act via a haploinsufficiency mechanism, disrupting both the protein synthesis and integrated stress response functions of EEF1A2. Our studies provide evidence that EEF1A2 is highly intolerant to variation and that de novo pathogenic variants lead to an epileptic-dyskinetic encephalopathy with both neurodevelopmental and neurodegenerative features. Developmental features may be driven by impaired synaptic protein synthesis during early brain development while progressive symptoms may be linked to an impaired ability to handle cytotoxic stressors.
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http://dx.doi.org/10.1002/humu.24015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7292794PMC
July 2020

Inherited RORB pathogenic variants: Overlap of photosensitive genetic generalized and occipital lobe epilepsy.

Epilepsia 2020 04 12;61(4):e23-e29. Epub 2020 Mar 12.

Department of Medicine, Epilepsy Research Centre, Austin Health, University of Melbourne, Melbourne, Victoria, Australia.

Variants in RORB have been reported in eight individuals with epilepsy, with phenotypes ranging from eyelid myoclonia with absence epilepsy to developmental and epileptic encephalopathies. We identified novel RORB variants in 11 affected individuals from four families. One was from whole genome sequencing and three were from RORB screening of three epilepsy cohorts: developmental and epileptic encephalopathies (n = 1021), overlap of generalized and occipital epilepsy (n = 84), and photosensitivity (n = 123). Following interviews and review of medical records, individuals' seizure and epilepsy syndromes were classified. Three novel missense variants and one exon 3 deletion were predicted to be pathogenic by in silico tools, not found in population databases, and located in key evolutionary conserved domains. Median age at seizure onset was 3.5 years (0.5-10 years). Generalized, predominantly absence and myoclonic, and occipital seizures were seen in all families, often within the same individual (6/11). All individuals with epilepsy were photosensitive, and seven of 11 had cognitive abnormalities. Electroencephalograms showed generalized spike and wave and/or polyspike and wave. Here we show a striking RORB phenotype of overlap of photosensitive generalized and occipital epilepsy in both individuals and families. This is the first report of a gene associated with this overlap of epilepsy syndromes.
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http://dx.doi.org/10.1111/epi.16475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363501PMC
April 2020

Levetiracetam efficacy in PCDH19 Girls Clustering Epilepsy.

Eur J Paediatr Neurol 2020 Jan 3;24:142-147. Epub 2020 Jan 3.

Department of Medicine, Epilepsy Research Centre, The University of Melbourne, Austin Health, Melbourne, VIC, Australia; Department of Paediatrics, Royal Children's Hospital, The University of Melbourne, VIC, Australia; The Florey Institute and Murdoch Children's Research Institute, Melbourne, VIC, Australia.

Background: PCDH19 Girls clustering epilepsy (GCE) has a phenotypic spectrum that includes developmental and epileptic encephalopathy. PCDH19-GCE presents with clusters of seizures in the first years of life. Although patients typically outgrow their seizures, many are left with intellectual disability. Here we retrospectively assess the effect of levetiracetam in two independent cohorts of females with PCDH19-GCE.

Methods: Cohort A was identified by searching our epilepsy genetics research database for girls with PCDH19-GCE who had trialled levetiracetam. Cohort B consisted of girls aged 2 years or older, including women, participating in an international online questionnaire. Information regarding seizure frequency and levetiracetam use was obtained by in-person patient interview and review of clinical records for cohort A, and by patient report for cohort B.

Results: Cohort A consisted of 17 females, aged 3-37 years, who had a trial of levetiracetam at an average age of 10.7 years. 13/17 females became seizure free for >12 months; while 10/17 remained seizure free for >24 months. Cohort B comprised 62 females, aged 1.5-41 years. 26/62 became seizure free for >12 months, and 19/62 for >24 months on levetiracetam therapy.

Discussion: Levetiracetam was effective in two cohorts of females with PCDH19-GCE where 42% and 76% of females became seizure free for >12 months, respectively. Levetiracetam is an effective therapy for females with PCDH19-GCE and should be considered early in the management of the highly refractory clusters of seizures that characterise this genetic disease.
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http://dx.doi.org/10.1016/j.ejpn.2019.12.020DOI Listing
January 2020

Intronic ATTTC repeat expansions in STARD7 in familial adult myoclonic epilepsy linked to chromosome 2.

Nat Commun 2019 10 29;10(1):4920. Epub 2019 Oct 29.

Adelaide Medical School and Robinson Research Institute, University of Adelaide, Adelaide, 5005, SA, Australia.

Familial Adult Myoclonic Epilepsy (FAME) is characterised by cortical myoclonic tremor usually from the second decade of life and overt myoclonic or generalised tonic-clonic seizures. Four independent loci have been implicated in FAME on chromosomes (chr) 2, 3, 5 and 8. Using whole genome sequencing and repeat primed PCR, we provide evidence that chr2-linked FAME (FAME2) is caused by an expansion of an ATTTC pentamer within the first intron of STARD7. The ATTTC expansions segregate in 158/158 individuals typically affected by FAME from 22 pedigrees including 16 previously reported families recruited worldwide. RNA sequencing from patient derived fibroblasts shows no accumulation of the AUUUU or AUUUC repeat sequences and STARD7 gene expression is not affected. These data, in combination with other genes bearing similar mutations that have been implicated in FAME, suggest ATTTC expansions may cause this disorder, irrespective of the genomic locus involved.
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http://dx.doi.org/10.1038/s41467-019-12671-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6820779PMC
October 2019

The epileptology of GNB5 encephalopathy.

Epilepsia 2019 11 20;60(11):e121-e127. Epub 2019 Oct 20.

Department of Paediatrics and Child Health, University of Otago, Wellington, New Zealand.

Pathogenic variants in GNB5 cause an autosomal recessive neurodevelopmental disorder with neonatal sinus bradycardia. Seizures or epilepsy occurred in 10 of 22 previously reported cases, including 6 children from one family. We delineate the epileptology of GNB5 encephalopathy. Our nine patients, including five new patients, were from seven families. Epileptic spasms were the most frequent seizure type, occurring in eight of nine patients, and began at a median age of 3 months (2 months to 3 years). Focal seizures preceded spasms in three children, with onset at 7 days, 11 days, and 4 months. One child presented with convulsive status epilepticus at 6 months. Three children had burst suppression on electroencephalography (EEG), three had hypsarrhythmia, and one evolved from burst suppression to hypsarrhythmia. Background slowing was present in all after age 3 years. Magnetic resonance imaging (MRI) showed cerebral atrophy in one child and cerebellar atrophy in another. All nine had abnormal development prior to seizure onset and ultimately had profound impairment without regression. Hypotonia was present in all, with contractures developing in two older patients. All individuals had biallelic pathogenic variants in GNB5, predicted by in silico tools to result in protein truncation and loss-of-function. GNB5 developmental and epileptic encephalopathy is characterized by epileptic spasms, focal seizures, and profound impairment.
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http://dx.doi.org/10.1111/epi.16372DOI Listing
November 2019

The Genetic Landscape of Epilepsy of Infancy with Migrating Focal Seizures.

Ann Neurol 2019 12;86(6):821-831

Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia.

Objective: Epilepsy of infancy with migrating focal seizures (EIMFS) is one of the most severe developmental and epileptic encephalopathies. We delineate the genetic causes and genotype-phenotype correlations of a large EIMFS cohort.

Methods: Phenotypic and molecular data were analyzed on patients recruited through an international collaborative study.

Results: We ascertained 135 patients from 128 unrelated families. Ninety-three of 135 (69%) had causative variants (42/55 previously reported) across 23 genes, including 9 novel EIMFS genes: de novo dominant GABRA1, GABRB1, ATP1A3; X-linked CDKL5, PIGA; and recessive ITPA, AIMP1, KARS, WWOX. The most frequently implicated genes were KCNT1 (36/135, 27%) and SCN2A (10/135, 7%). Mosaicism occurred in 2 probands (SCN2A, GABRB3) and 3 unaffected mothers (KCNT1). Median age at seizure onset was 4 weeks, with earlier onset in the SCN2A, KCNQ2, and BRAT1 groups. Epileptic spasms occurred in 22% patients. A total of 127 patients had severe to profound developmental impairment. All but 7 patients had ongoing seizures. Additional features included microcephaly, movement disorders, spasticity, and scoliosis. Mortality occurred in 33% at median age 2 years 7 months.

Interpretation: We identified a genetic cause in 69% of patients with EIMFS. We highlight the genetic heterogeneity of EIMFS with 9 newly implicated genes, bringing the total number to 33. Mosaicism was observed in probands and parents, carrying critical implications for recurrence risk. EIMFS pathophysiology involves diverse molecular processes from gene and protein regulation to ion channel function and solute trafficking. ANN NEUROL 2019;86:821-831.
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http://dx.doi.org/10.1002/ana.25619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7423163PMC
December 2019

Expanding the genetic and phenotypic relevance of KCNB1 variants in developmental and epileptic encephalopathies: 27 new patients and overview of the literature.

Hum Mutat 2020 01 4;41(1):69-80. Epub 2019 Oct 4.

Department of Pediatric Neurology, Reference Centre for Rare Epilepsies, Hôpital Necker-Enfants Malades, Paris, France.

Developmental and epileptic encephalopathies (DEE) refer to a heterogeneous group of devastating neurodevelopmental disorders. Variants in KCNB1 have been recently reported in patients with early-onset DEE. KCNB1 encodes the α subunit of the delayed rectifier voltage-dependent potassium channel K 2.1. We review the 37 previously reported patients carrying 29 distinct KCNB1 variants and significantly expand the mutational spectrum describing 18 novel variants from 27 unreported patients. Most variants occur de novo and mainly consist of missense variants located on the voltage sensor and the pore domain of K 2.1. We also report the first inherited variant (p.Arg583*). KCNB1-related encephalopathies encompass a wide spectrum of neurodevelopmental disorders with predominant language difficulties and behavioral impairment. Eighty-five percent of patients developed epilepsies with variable syndromes and prognosis. Truncating variants in the C-terminal domain are associated with a less-severe epileptic phenotype. Overall, this report provides an up-to-date review of the mutational and clinical spectrum of KCNB1, strengthening its place as a causal gene in DEEs and emphasizing the need for further functional studies to unravel the underlying mechanisms.
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http://dx.doi.org/10.1002/humu.23915DOI Listing
January 2020

Generation of the induced human pluripotent stem cell lines CSSi009-A from a patient with a GNB5 pathogenic variant, and CSSi010-A from a CRISPR/Cas9 engineered GNB5 knock-out human cell line.

Stem Cell Res 2019 10 22;40:101547. Epub 2019 Aug 22.

Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy. Electronic address:

GNB5 loss-of-function pathogenic variants cause IDDCA, a rare autosomal recessive human genetic disease characterized by infantile onset of intellectual disability, sinus bradycardia, hypotonia, visual abnormalities, and epilepsy. We generated human induced pluripotent stem cells (hiPSCs) from skin fibroblasts of a patient with the homozygous c.136delG frameshift variant, and a GNB5 knock-out (KO) line by CRISPR/Cas9 editing. hiPSCs express common pluripotency markers and differentiate into the three germ layers. These lines represent a powerful cellular model to study the molecular basis of GNB5-related disorders as well as offer an in vitro model for drug screening.
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http://dx.doi.org/10.1016/j.scr.2019.101547DOI Listing
October 2019

Fragile Females: Case Series of Epilepsy in Girls With Disruption.

Pediatrics 2019 09 22;144(3). Epub 2019 Aug 22.

Department of Medicine, Epilepsy Research Centre, The University of Melbourne and Austin Health, Heidelberg, Victoria, Australia.

Girls with pathogenic variants in , the gene responsible for Fragile X syndrome, have received relatively little attention in the literature. The reports of girls with trinucleotide expansions or deletions affecting describe variable phenotypes; having normal intelligence and no severe neurologic sequelae is not uncommon. We reviewed epilepsy genetics research databases for girls with pathogenic variants and seizures to characterize the spectrum of epilepsy phenotypes. We identified 4 patients, 3 of whom had drug-resistant focal epilepsy. Two had severe developmental and epileptic encephalopathy with late-onset epileptic spasms. Our findings demonstrate that loss-of-function variants can result in severe neurologic phenotypes in girls. Similar cases may be missed because clinicians may not always perform Fragile X testing in girls, particularly those with severe neurodevelopmental impairment or late-onset spasms.
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http://dx.doi.org/10.1542/peds.2019-0599DOI Listing
September 2019

Autism and developmental disability caused by KCNQ3 gain-of-function variants.

Ann Neurol 2019 08 26;86(2):181-192. Epub 2019 Jun 26.

Department of Neurology, University of California, San Francisco, San Francisco, CA.

Objective: Recent reports have described single individuals with neurodevelopmental disability (NDD) harboring heterozygous KCNQ3 de novo variants (DNVs). We sought to assess whether pathogenic variants in KCNQ3 cause NDD and to elucidate the associated phenotype and molecular mechanisms.

Methods: Patients with NDD and KCNQ3 DNVs were identified through an international collaboration. Phenotypes were characterized by clinical assessment, review of charts, electroencephalographic (EEG) recordings, and parental interview. Functional consequences of variants were analyzed in vitro by patch-clamp recording.

Results: Eleven patients were assessed. They had recurrent heterozygous DNVs in KCNQ3 affecting residues R230 (R230C, R230H, R230S) and R227 (R227Q). All patients exhibited global developmental delay within the first 2 years of life. Most (8/11, 73%) were nonverbal or had a few words only. All patients had autistic features, and autism spectrum disorder (ASD) was diagnosed in 5 of 11 (45%). EEGs performed before 10 years of age revealed frequent sleep-activated multifocal epileptiform discharges in 8 of 11 (73%). For 6 of 9 (67%) recorded between 1.5 and 6 years of age, spikes became near-continuous during sleep. Interestingly, most patients (9/11, 82%) did not have seizures, and no patient had seizures in the neonatal period. Voltage-clamp recordings of the mutant KCNQ3 channels revealed gain-of-function (GoF) effects.

Interpretation: Specific GoF variants in KCNQ3 cause NDD, ASD, and abundant sleep-activated spikes. This new phenotype contrasts both with self-limited neonatal epilepsy due to KCNQ3 partial loss of function, and with the neonatal or infantile onset epileptic encephalopathies due to KCNQ2 GoF. ANN NEUROL 2019;86:181-192.
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http://dx.doi.org/10.1002/ana.25522DOI Listing
August 2019

Double somatic mosaicism in a child with Dravet syndrome.

Neurol Genet 2019 Jun 19;5(3):e333. Epub 2019 Apr 19.

Division of Genetic Medicine (A.M.M., A.S.B., H.C.M.), Department of Pediatrics, University of Washington, Seattle, WA; Department of Paediatrics and Child Health (C.K.), University of Otago, Wellington, New Zealand; Department of Medicine (A.L.S., I.E.S.), Epilepsy Research Centre, The University of Melbourne, Austin Health, Heidelberg, Australia; The Florey Institute and Murdoch Children's Research Institute (I.E.S.), Parkville, Australia; Department of Neurology (I.E.S.), Royal Children's Hospital, Parkville, Australia; and Department of Paediatrics and Child Health (L.G.S.), University of Otago, Wellington, New Zealand.

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http://dx.doi.org/10.1212/NXG.0000000000000333DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6481227PMC
June 2019

De Novo Pathogenic Variants in CACNA1E Cause Developmental and Epileptic Encephalopathy with Contractures, Macrocephaly, and Dyskinesias.

Authors:
Katherine L Helbig Robert J Lauerer Jacqueline C Bahr Ivana A Souza Candace T Myers Betül Uysal Niklas Schwarz Maria A Gandini Sun Huang Boris Keren Cyril Mignot Alexandra Afenjar Thierry Billette de Villemeur Delphine Héron Caroline Nava Stéphanie Valence Julien Buratti Christina R Fagerberg Kristina P Soerensen Maria Kibaek Erik-Jan Kamsteeg David A Koolen Boudewijn Gunning H Jurgen Schelhaas Michael C Kruer Jordana Fox Somayeh Bakhtiari Randa Jarrar Sergio Padilla-Lopez Kristin Lindstrom Sheng Chih Jin Xue Zeng Kaya Bilguvar Antigone Papavasileiou Qinghe Xing Changlian Zhu Katja Boysen Filippo Vairo Brendan C Lanpher Eric W Klee Jan-Mendelt Tillema Eric T Payne Margot A Cousin Teresa M Kruisselbrink Myra J Wick Joshua Baker Eric Haan Nicholas Smith Azita Sadeghpour Erica E Davis Nicholas Katsanis Mark A Corbett Alastair H MacLennan Jozef Gecz Saskia Biskup Eva Goldmann Lance H Rodan Elizabeth Kichula Eric Segal Kelly E Jackson Alexander Asamoah David Dimmock Julie McCarrier Lorenzo D Botto Francis Filloux Tatiana Tvrdik Gregory D Cascino Sherry Klingerman Catherine Neumann Raymond Wang Jessie C Jacobsen Melinda A Nolan Russell G Snell Klaus Lehnert Lynette G Sadleir Britt-Marie Anderlid Malin Kvarnung Renzo Guerrini Michael J Friez Michael J Lyons Jennifer Leonhard Gabriel Kringlen Kari Casas Christelle M El Achkar Lacey A Smith Alexander Rotenberg Annapurna Poduri Alba Sanchis-Juan Keren J Carss Julia Rankin Adam Zeman F Lucy Raymond Moira Blyth Bronwyn Kerr Karla Ruiz Jill Urquhart Imelda Hughes Siddharth Banka Ulrike B S Hedrich Ingrid E Scheffer Ingo Helbig Gerald W Zamponi Holger Lerche Heather C Mefford

Am J Hum Genet 2019 Mar;104(3):562

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http://dx.doi.org/10.1016/j.ajhg.2019.02.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6407522PMC
March 2019

Schizophrenia is a later-onset feature of PCDH19 Girls Clustering Epilepsy.

Epilepsia 2019 03 3;60(3):429-440. Epub 2019 Mar 3.

Division of Neurology, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada.

Objective: To investigate the occurrence of psychosis and serious behavioral problems in females with protocadherin 19 gene (PCDH19) pathogenic variants.

Methods: We evaluated whether psychosis and serious behavioral problems had occurred in 60 females (age 2-75 years) with PCDH19 pathogenic variants belonging to 35 families. Patients were identified from epilepsy genetics databases in Australia, New Zealand, the United States, and Canada. Neurologic and psychiatric disorders were diagnosed using standard methods.

Results: Eight of 60 females (13%) from 7 families developed a psychotic disorder: schizophrenia (6), schizoaffective disorder (1), or an unspecified psychotic disorder (1). Median age at onset of psychotic symptoms was 21 years (range 11-28 years). In our cohort of 39 females aged 11 years or older, 8 (21%) developed a psychotic disorder. Seven had ongoing seizures at onset of psychosis, with 2 continuing to have seizures when psychosis recurred. Psychotic disorders occurred in the setting of mild (4), moderate (2), or severe (1) intellectual disability, or normal intellect (1). Preexisting behavioral problems occurred in 4 patients, and autism spectrum disorder in 3. Two additional females (3%) had psychotic features with other conditions: an adolescent had recurrent episodes of postictal psychosis, and a 75-year-old woman had major depression with psychotic features. A further 3 adolescents (5%) with moderate to severe intellectual disability had onset of severe behavioral disturbance, or significant worsening.

Significance: We identify that psychotic disorders, including schizophrenia, are a later-onset manifestation of PCDH19 Girls Clustering Epilepsy. Affected girls and women should be carefully monitored for later-onset psychiatric disorders.
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http://dx.doi.org/10.1111/epi.14678DOI Listing
March 2019

Efficacy of cannabinoids in paediatric epilepsy.

Dev Med Child Neurol 2019 01 6;61(1):13-18. Epub 2018 Nov 6.

Department of Paediatrics and Child Health, University of Otago, Wellington, New Zealand.

There are hundreds of compounds found in the marijuana plant, each contributing differently to the antiepileptic and psychiatric effects. Cannabidiol (CBD) has the most evidence of antiepileptic efficacy and does not have the psychoactive effects of ∆ -tetrahydrocannabinol. CBD does not act via cannabinoid receptors and its antiepileptic mechanism of action is unknown. Despite considerable community interest in the use of CBD for paediatric epilepsy, there has been little evidence for its use apart from anecdotal reports, until the last year. Three randomized, placebo-controlled, double-blind trials in Dravet syndrome and Lennox-Gastaut syndrome found that CBD produced a 38% to 41% median reduction in all seizures compared to 13% to 19% on placebo. Similarly, CBD resulted in a 39% to 46% responder rate (50% convulsive or drop-seizure reduction) compared to 14% to 27% on placebo. CBD was well tolerated; however, sedation, diarrhoea, and decreased appetite were frequent. CBD shows similar efficacy to established antiepileptic drugs. WHAT THIS PAPER ADDS: Cannabidiol (CBD) shows similar efficacy in the severe paediatric epilepsies to other antiepileptic drugs. Careful down-titration of benzodiazepines is essential to minimize sedation with adjunctive CBD.
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http://dx.doi.org/10.1111/dmcn.14087DOI Listing
January 2019

De Novo Pathogenic Variants in CACNA1E Cause Developmental and Epileptic Encephalopathy with Contractures, Macrocephaly, and Dyskinesias.

Authors:
Katherine L Helbig Robert J Lauerer Jacqueline C Bahr Ivana A Souza Candace T Myers Betül Uysal Niklas Schwarz Maria A Gandini Sun Huang Boris Keren Cyril Mignot Alexandra Afenjar Thierry Billette de Villemeur Delphine Héron Caroline Nava Stéphanie Valence Julien Buratti Christina R Fagerberg Kristina P Soerensen Maria Kibaek Erik-Jan Kamsteeg David A Koolen Boudewijn Gunning H Jurgen Schelhaas Michael C Kruer Jordana Fox Somayeh Bakhtiari Randa Jarrar Sergio Padilla-Lopez Kristin Lindstrom Sheng Chih Jin Xue Zeng Kaya Bilguvar Antigone Papavasileiou Qinghe Xing Changlian Zhu Katja Boysen Filippo Vairo Brendan C Lanpher Eric W Klee Jan-Mendelt Tillema Eric T Payne Margot A Cousin Teresa M Kruisselbrink Myra J Wick Joshua Baker Eric Haan Nicholas Smith Azita Sadeghpour Erica E Davis Nicholas Katsanis Mark A Corbett Alastair H MacLennan Jozef Gecz Saskia Biskup Eva Goldmann Lance H Rodan Elizabeth Kichula Eric Segal Kelly E Jackson Alexander Asamoah David Dimmock Julie McCarrier Lorenzo D Botto Francis Filloux Tatiana Tvrdik Gregory D Cascino Sherry Klingerman Catherine Neumann Raymond Wang Jessie C Jacobsen Melinda A Nolan Russell G Snell Klaus Lehnert Lynette G Sadleir Britt-Marie Anderlid Malin Kvarnung Renzo Guerrini Michael J Friez Michael J Lyons Jennifer Leonhard Gabriel Kringlen Kari Casas Christelle M El Achkar Lacey A Smith Alexander Rotenberg Annapurna Poduri Alba Sanchis-Juan Keren J Carss Julia Rankin Adam Zeman F Lucy Raymond Moira Blyth Bronwyn Kerr Karla Ruiz Jill Urquhart Imelda Hughes Siddharth Banka Ulrike B S Hedrich Ingrid E Scheffer Ingo Helbig Gerald W Zamponi Holger Lerche Heather C Mefford

Am J Hum Genet 2018 11 18;103(5):666-678. Epub 2018 Oct 18.

Division of Genetic Medicine, University of Washington, Seattle, WA 98195, USA. Electronic address:

Developmental and epileptic encephalopathies (DEEs) are severe neurodevelopmental disorders often beginning in infancy or early childhood that are characterized by intractable seizures, abundant epileptiform activity on EEG, and developmental impairment or regression. CACNA1E is highly expressed in the central nervous system and encodes the α-subunit of the voltage-gated Ca2.3 channel, which conducts high voltage-activated R-type calcium currents that initiate synaptic transmission. Using next-generation sequencing techniques, we identified de novo CACNA1E variants in 30 individuals with DEE, characterized by refractory infantile-onset seizures, severe hypotonia, and profound developmental impairment, often with congenital contractures, macrocephaly, hyperkinetic movement disorders, and early death. Most of the 14, partially recurring, variants cluster within the cytoplasmic ends of all four S6 segments, which form the presumed Ca2.3 channel activation gate. Functional analysis of several S6 variants revealed consistent gain-of-function effects comprising facilitated voltage-dependent activation and slowed inactivation. Another variant located in the domain II S4-S5 linker results in facilitated activation and increased current density. Five participants achieved seizure freedom on the anti-epileptic drug topiramate, which blocks R-type calcium channels. We establish pathogenic variants in CACNA1E as a cause of DEEs and suggest facilitated R-type calcium currents as a disease mechanism for human epilepsy and developmental disorders.
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http://dx.doi.org/10.1016/j.ajhg.2018.09.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6216110PMC
November 2018

De Novo Variants in the F-Box Protein FBXO11 in 20 Individuals with a Variable Neurodevelopmental Disorder.

Am J Hum Genet 2018 08 26;103(2):305-316. Epub 2018 Jul 26.

Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany. Electronic address:

Next-generation sequencing combined with international data sharing has enormously facilitated identification of new disease-associated genes and mutations. This is particularly true for genetically extremely heterogeneous entities such as neurodevelopmental disorders (NDDs). Through exome sequencing and world-wide collaborations, we identified and assembled 20 individuals with de novo variants in FBXO11. They present with mild to severe developmental delay associated with a range of features including short (4/20) or tall (2/20) stature, obesity (5/20), microcephaly (4/19) or macrocephaly (2/19), behavioral problems (17/20), seizures (5/20), cleft lip or palate or bifid uvula (3/20), and minor skeletal anomalies. FBXO11 encodes a member of the F-Box protein family, constituting a subunit of an E3-ubiquitin ligase complex. This complex is involved in ubiquitination and proteasomal degradation and thus in controlling critical biological processes by regulating protein turnover. The identified de novo aberrations comprise two large deletions, ten likely gene disrupting variants, and eight missense variants distributed throughout FBXO11. Structural modeling for missense variants located in the CASH or the Zinc-finger UBR domains suggests destabilization of the protein. This, in combination with the observed spectrum and localization of identified variants and the lack of apparent genotype-phenotype correlations, is compatible with loss of function or haploinsufficiency as an underlying mechanism. We implicate de novo missense and likely gene disrupting variants in FBXO11 in a neurodevelopmental disorder with variable intellectual disability and various other features.
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http://dx.doi.org/10.1016/j.ajhg.2018.07.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6080769PMC
August 2018

A systematic review and meta-analysis of 271 PCDH19-variant individuals identifies psychiatric comorbidities, and association of seizure onset and disease severity.

Mol Psychiatry 2019 02 11;24(2):241-251. Epub 2018 Jun 11.

Adelaide Medical School, The University of Adelaide, Adelaide, SA, Australia.

Epilepsy and Mental Retardation Limited to Females (EFMR) is an infantile onset disorder characterized by clusters of seizures. EFMR is due to mutations in the X-chromosome gene PCDH19, and is underpinned by cellular mosaicism due to X-chromosome inactivation in females or somatic mutation in males. This review characterizes the neuropsychiatric profile of this disorder and examines the association of clinical and molecular factors with neuropsychiatric outcomes. Data were extracted from 38 peer-reviewed original articles including 271 individual cases. We found that seizure onset ≤12 months was significantly associated (p = 4.127 × 10) with more severe intellectual disability, compared with onset >12 months. We identified two recurrent variants p.Asn340Ser and p.Tyr366Leufs*10 occurring in 25 (20 unrelated) and 30 (11 unrelated) cases, respectively. PCDH19 mutations were associated with psychiatric comorbidities in approximately 60% of females, 80% of affected mosaic males, and reported in nine hemizygous males. Hyperactive, autistic, and obsessive-compulsive features were most frequently reported. There were no genotype-phenotype associations in the individuals with recurrent variants or the group overall. Age at seizure onset can be used to provide more informative prognostic counseling.
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http://dx.doi.org/10.1038/s41380-018-0066-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6344372PMC
February 2019

Heart rate variability in epilepsy: A potential biomarker of sudden unexpected death in epilepsy risk.

Epilepsia 2018 07 6;59(7):1372-1380. Epub 2018 Jun 6.

Department of Medicine, Epilepsy Research Centre, Austin Health, University of Melbourne, Heidelberg, Victoria, Australia.

Objective: Sudden unexpected death in epilepsy (SUDEP) is a tragic and devastating event for which the underlying pathophysiology remains poorly understood; this study investigated whether abnormalities in heart rate variability (HRV) are linked to SUDEP in patients with epilepsy due to mutations in sodium channel (SCN) genes.

Methods: We retrospectively evaluated HRV in epilepsy patients using electroencephalographic studies to study the potential contribution of autonomic dysregulation to SUDEP risk. We extracted HRV data, in wakefulness and sleep, from 80 patients with drug-resistant epilepsy, including 40 patients with mutations in SCN genes and 40 control patients with non-SCN drug-resistant epilepsy. From the SCN group, 10 patients had died of SUDEP. We compared HRV between SUDEP and non-SUDEP groups, specifically studying awake HRV and sleep:awake HRV ratios.

Results: The SUDEP patients had the most severe autonomic dysregulation, showing lower awake HRV and either extremely high or extremely low ratios of sleep-to-awake HRV in a subgroup analysis. A secondary analysis comparing the SCN and non-SCN groups indicated that autonomic dysfunction was slightly worse in the SCN epilepsy group.

Significance: These findings suggest that autonomic dysfunction is associated with SUDEP risk in patients with epilepsy due to sodium channel mutations. The relationship of HRV to SUDEP merits further study; HRV may eventually have potential as a biomarker of SUDEP risk, which would allow for more informed counseling of patients and families, and also serve as a useful outcome measure for research aimed at developing therapies and interventions to reduce SUDEP risk.
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http://dx.doi.org/10.1111/epi.14438DOI Listing
July 2018

Do neurologists around the world agree when diagnosing epilepsy? - Results of an international EpiNet study.

Epilepsy Res 2018 01 26;139:43-50. Epub 2017 Oct 26.

Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Australia. Electronic address:

Objective: Previous studies have shown moderate agreement between physicians when diagnosing epilepsy, but have included small numbers. The EpiNet study group was established to undertake multicentre clinical trials in epilepsy. Before commencing trials, we wanted to determine levels of agreement between physicians from different countries and different health systems when diagnosing epilepsy, specific seizure types and etiologies.

Methods: 30 Case scenarios describing six children and 24 adults with paroxysmal events (21 epileptic seizures, nine non-epileptic attacks) were presented to physicians with an interest in epilepsy. Physicians were asked how likely was a diagnosis of epilepsy; if seizures were generalised or focal; and the likely etiology. For 23 cases, clinical information was presented in Step 1, and investigations in Step 2.

Results: 189 Participants from 36 countries completed the 30 cases. Levels of agreement were determined for 154 participants who provided details regarding their clinical experience. There was substantial agreement for diagnosis of epilepsy (kappa=0.61); agreement was fair to moderate for seizure type(s) (kappa=0.40) and etiology (kappa=0.41). For 23 cases with two steps, agreement increased from step 1 to step 2 for diagnosis of epilepsy (kappa 0.56-0.70), seizure type(s) (kappa 0.38-0.52), and etiology (kappa 0.38-0.47). Agreement was better for 53 epileptologists (diagnosis of epilepsy, kappa=0.66) than 56 neurologists with a special interest in epilepsy (kappa=0.58). Levels of agreement differed slightly between physicians practicing in different parts of the world, between child and adult neurologists, and according to one's experience with epilepsy.

Conclusion: Although there is substantial agreement when epileptologists diagnose epilepsy, there is less agreement for diagnoses of seizure types and etiology. Further education of physicians regarding semiology of different seizure types is required. Differences in approach to diagnosis, both between physicians and between countries, could impact negatively on clinical trials of anti-epileptic drugs.
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http://dx.doi.org/10.1016/j.eplepsyres.2017.10.014DOI Listing
January 2018

High Rate of Recurrent De Novo Mutations in Developmental and Epileptic Encephalopathies.

Authors:
Fadi F Hamdan Candace T Myers Patrick Cossette Philippe Lemay Dan Spiegelman Alexandre Dionne Laporte Christina Nassif Ousmane Diallo Jean Monlong Maxime Cadieux-Dion Sylvia Dobrzeniecka Caroline Meloche Kyle Retterer Megan T Cho Jill A Rosenfeld Weimin Bi Christine Massicotte Marguerite Miguet Ledia Brunga Brigid M Regan Kelly Mo Cory Tam Amy Schneider Georgie Hollingsworth David R FitzPatrick Alan Donaldson Natalie Canham Edward Blair Bronwyn Kerr Andrew E Fry Rhys H Thomas Joss Shelagh Jane A Hurst Helen Brittain Moira Blyth Robert Roger Lebel Erica H Gerkes Laura Davis-Keppen Quinn Stein Wendy K Chung Sara J Dorison Paul J Benke Emily Fassi Nicole Corsten-Janssen Erik-Jan Kamsteeg Frederic T Mau-Them Ange-Line Bruel Alain Verloes Katrin Õunap Monica H Wojcik Dara V F Albert Sunita Venkateswaran Tyson Ware Dean Jones Yu-Chi Liu Shekeeb S Mohammad Peyman Bizargity Carlos A Bacino Vincenzo Leuzzi Simone Martinelli Bruno Dallapiccola Marco Tartaglia Lubov Blumkin Klaas J Wierenga Gabriela Purcarin James J O'Byrne Sylvia Stockler Anna Lehman Boris Keren Marie-Christine Nougues Cyril Mignot Stéphane Auvin Caroline Nava Susan M Hiatt Martina Bebin Yunru Shao Fernando Scaglia Seema R Lalani Richard E Frye Imad T Jarjour Stéphanie Jacques Renee-Myriam Boucher Emilie Riou Myriam Srour Lionel Carmant Anne Lortie Philippe Major Paola Diadori François Dubeau Guy D'Anjou Guillaume Bourque Samuel F Berkovic Lynette G Sadleir Philippe M Campeau Zoha Kibar Ronald G Lafrenière Simon L Girard Saadet Mercimek-Mahmutoglu Cyrus Boelman Guy A Rouleau Ingrid E Scheffer Heather C Mefford Danielle M Andrade Elsa Rossignol Berge A Minassian Jacques L Michaud

Am J Hum Genet 2017 Nov;101(5):664-685

Centre Hospitalier Universitaire Sainte-Justine Research Center, Montreal, QC H3T1C5, Canada; Department of Neurosciences, Université de Montréal, Montreal, QC H3T1J4, Canada; Department of Pediatrics, Université de Montréal, Montreal, QC H3T1C5, Canada. Electronic address:

Developmental and epileptic encephalopathy (DEE) is a group of conditions characterized by the co-occurrence of epilepsy and intellectual disability (ID), typically with developmental plateauing or regression associated with frequent epileptiform activity. The cause of DEE remains unknown in the majority of cases. We performed whole-genome sequencing (WGS) in 197 individuals with unexplained DEE and pharmaco-resistant seizures and in their unaffected parents. We focused our attention on de novo mutations (DNMs) and identified candidate genes containing such variants. We sought to identify additional subjects with DNMs in these genes by performing targeted sequencing in another series of individuals with DEE and by mining various sequencing datasets. We also performed meta-analyses to document enrichment of DNMs in candidate genes by leveraging our WGS dataset with those of several DEE and ID series. By combining these strategies, we were able to provide a causal link between DEE and the following genes: NTRK2, GABRB2, CLTC, DHDDS, NUS1, RAB11A, GABBR2, and SNAP25. Overall, we established a molecular diagnosis in 63/197 (32%) individuals in our WGS series. The main cause of DEE in these individuals was de novo point mutations (53/63 solved cases), followed by inherited mutations (6/63 solved cases) and de novo CNVs (4/63 solved cases). De novo missense variants explained a larger proportion of individuals in our series than in other series that were primarily ascertained because of ID. Moreover, these DNMs were more frequently recurrent than those identified in ID series. These observations indicate that the genetic landscape of DEE might be different from that of ID without epilepsy.
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http://dx.doi.org/10.1016/j.ajhg.2017.09.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673604PMC
November 2017

De Novo Mutations in PPP3CA Cause Severe Neurodevelopmental Disease with Seizures.

Am J Hum Genet 2017 Oct 21;101(4):516-524. Epub 2017 Sep 21.

Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA. Electronic address:

Exome sequencing has readily enabled the discovery of the genetic mutations responsible for a wide range of diseases. This success has been particularly remarkable in the severe epilepsies and other neurodevelopmental diseases for which rare, often de novo, mutations play a significant role in disease risk. Despite significant progress, the high genetic heterogeneity of these disorders often requires large sample sizes to identify a critical mass of individuals with disease-causing mutations in a single gene. By pooling genetic findings across multiple studies, we have identified six individuals with severe developmental delay (6/6), refractory seizures (5/6), and similar dysmorphic features (3/6), each harboring a de novo mutation in PPP3CA. PPP3CA encodes the alpha isoform of a subunit of calcineurin. Calcineurin encodes a calcium- and calmodulin-dependent serine/threonine protein phosphatase that plays a role in a wide range of biological processes, including being a key regulator of synaptic vesicle recycling at nerve terminals. Five individuals with de novo PPP3CA mutations were identified among 4,760 trio probands with neurodevelopmental diseases; this is highly unlikely to occur by chance (p = 1.2 × 10) given the size and mutability of the gene. Additionally, a sixth individual with a de novo mutation in PPP3CA was connected to this study through GeneMatcher. Based on these findings, we securely implicate PPP3CA in early-onset refractory epilepsy and further support the emerging role for synaptic dysregulation in epilepsy.
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http://dx.doi.org/10.1016/j.ajhg.2017.08.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5630160PMC
October 2017