Publications by authors named "Katrine M Johannesen"

28 Publications

  • Page 1 of 1

Gain-of-function variants in GABRD reveal a novel pathway for neurodevelopmental disorders and epilepsy.

Brain 2021 Oct 11. Epub 2021 Oct 11.

Department of Epilepsy Genetics and Personalized Treatment, The Danish Epilepsy Centre; Dianalund, Denmark.

A potential link between GABRD encoding the δ subunit of extrasynaptic GABAA receptors and neurodevelopmental disorders has largely been disregarded due to conflicting conclusions from early studies. However, we identified seven heterozygous missense GABRD variants in 10 patients with neurodevelopmental disorders and generalized epilepsy. One variant occurred in two sibs of healthy parents with presumed somatic mosaicism, another segregated with the disease in three affected family members, and the remaining five occurred de novo in sporadic patients. Electrophysiological measurements were used to determine the functional consequence of the seven missense δ subunit variants in receptor combinations of α1β3δ and α4β2δ GABAA receptors. This was accompanied by analysis of electro-clinical phenotypes of the affected individuals. We determined that five of the seven variants caused altered function of the resulting α1β3δ and α4β2δ GABAA receptors. Surprisingly, four of the five variants led to gain-of-function effects whereas one led to a loss-of-function effect. The stark differences between the gain-of-function and loss-of function effects were mirrored by the clinical phenotypes. Six patients with gain-of-function variants shared common phenotypes: neurodevelopmental disorders with generalized epilepsy, behavioral issues, and various degrees of intellectual disability. Six patients with gain-of-function variants shared common phenotypes: neurodevelopmental disorders with behavioral issues, various degrees of intellectual disability, generalized epilepsy with atypical absences and generalized myoclonic and/or bilateral tonic-clonic seizures. The EEG showed qualitative analogies among the different gain-of-function variant carriers consisting of focal slowing in the occipital regions often preceding irregular generalized epileptiform discharges, with frontal predominance. In contrast, the one patient carrying a loss-of-function variant had normal intelligence, no seizure history but has a diagnosis of autism spectrum disorder and suffering from elevated internalizing psychiatric symptoms. We hypothesize that increase in tonic GABA-evoked current levels mediated by δ-containing extrasynaptic GABAA receptors lead to abnormal neurotransmission, which represent a novel mechanism for severe neurodevelopmental disorders. In support of this, the electro-clinical findings for the gain-of-function GABRD variants resemble the phenotypic spectrum reported in patients with missense SLC6A1 (GABA uptake transporter) variants. This also indicates that the phenomenon of extrasynaptic receptor over-activity is observed in a broader range of patients with neurodevelopmental disorders, since SLC6A1 loss-of-function variants also lead to overactive extrasynaptic δ-containing GABAA receptors. These findings have implications when selecting potential treatment options, since a substantial portion of available anti-seizure medication act by enhancing GABAergic function either directly or indirectly, which could exacerbate symptoms in patients with gain-of-function GABRD variants.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/brain/awab391DOI Listing
October 2021

Genotype-phenotype correlations in SCN8A-related disorders reveal prognostic and therapeutic implications.

Brain 2021 Aug 25. Epub 2021 Aug 25.

National Centre for Rare Epilepsy-Related Disorders, Oslo University Hospital, 0001 Oslo, Norway.

We report detailed functional analyses and genotype-phenotype correlations in 392 individuals carrying disease-causing variants in SCN8A, encoding the voltage-gated Na+ channel NaV1.6, with the aim of describing clinical phenotypes related to functional effects. Six different clinical subgroups could be identified: 1) Benign familial infantile epilepsy (BFIE) (n = 15, normal cognition, treatable seizures), 2) intermediate epilepsy (n = 33, mild ID, partially pharmaco-responsive), 3) developmental and epileptic encephalopathy (DEE, n = 177, severe ID, majority pharmaco-resistant), 4) generalized epilepsy (n = 20, mild to moderate ID, frequently with absence seizures), 5) unclassifiable epilepsy (n = 127), and 6) neurodevelopmental disorder without epilepsy (n = 20, mild to moderate ID). Groups 1-3 presented with focal or multifocal seizures (median age of onset: four months) and focal epileptiform discharges, whereas the onset of seizures in group 4 was later (median: 42 months) with generalized epileptiform discharges. We performed functional studies expressing missense variants in ND7/23 neuroblastoma cells and primary neuronal cultures using recombinant tetrodotoxin-insensitive human NaV1.6 channels and whole-cell patch-clamping. Two variants causing DEE showed a strong gain-of-function (GOF, hyperpolarising shift of steady-state activation, strongly increased neuronal firing rate), and one variant causing BFIE or intermediate epilepsy showed a mild GOF (defective fast inactivation, less increased firing). In contrast, all three variants causing generalized epilepsy induced a loss-of-function (LOF, reduced current amplitudes, depolarising shift of steady-state activation, reduced neuronal firing). Including previous studies, functional effects were known for 170 individuals. All 136 individuals carrying a functionally tested GOF variant had either focal (97, groups 1-3), or unclassifiable epilepsy (39), whereas 34 with a LOF variant had either generalized (14), no (11) or unclassifiable (6) epilepsy; only three had DEE. Computational modeling in the GOF group revealed a significant correlation between the severity of the electrophysiological and clinical phenotypes. GOF variant carriers responded significantly better to sodium channel blockers (SCBs) than to other anti-seizure medications, and the same applied for all individuals of groups 1-3. In conclusion, our data reveal clear genotype-phenotype correlations between age at seizure onset, type of epilepsy and gain- or loss-of-function effects of SCN8A variants. Generalized epilepsy with absence seizures is the main epilepsy phenotype of LOF variant carriers and the extent of the electrophysiological dysfunction of the GOF variants is a main determinant of the severity of the clinical phenotype in focal epilepsies. Our pharmacological data indicate that SCBs present a treatment option in SCN8A-related focal epilepsy with onset in the first year of life.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/brain/awab321DOI Listing
August 2021

Integrative approach to interpret DYRK1A variants, leading to a frequent neurodevelopmental disorder.

Genet Med 2021 Aug 3. Epub 2021 Aug 3.

Normandie Univ, UNIROUEN, Inserm U1245 and Rouen University Hospital, Department of Genetics and Reference Center for Developmental Disorders, F 76000, Normandy Center for Genomic and Personalized Medicine, Rouen, France.

Purpose: DYRK1A syndrome is among the most frequent monogenic forms of intellectual disability (ID). We refined the molecular and clinical description of this disorder and developed tools to improve interpretation of missense variants, which remains a major challenge in human genetics.

Methods: We reported clinical and molecular data for 50 individuals with ID harboring DYRK1A variants and developed (1) a specific DYRK1A clinical score; (2) amino acid conservation data generated from 100 DYRK1A sequences across different taxa; (3) in vitro overexpression assays to study level, cellular localization, and kinase activity of DYRK1A mutant proteins; and (4) a specific blood DNA methylation signature.

Results: This integrative approach was successful to reclassify several variants as pathogenic. However, we questioned the involvement of some others, such as p.Thr588Asn, still reported as likely pathogenic, and showed it does not cause an obvious phenotype in mice.

Conclusion: Our study demonstrated the need for caution when interpreting variants in DYRK1A, even those occurring de novo. The tools developed will be useful to interpret accurately the variants identified in the future in this gene.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41436-021-01263-1DOI Listing
August 2021

Two GluN2B mutations affect multiple NMDAR-functions and instigate severe pediatric encephalopathy.

Elife 2021 07 2;10. Epub 2021 Jul 2.

Department of Neuroscience, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.

The N-methyl-D-aspartate receptors (NMDARs; GluNRS) are glutamate receptors, commonly located at excitatory synapses. Mutations affecting receptor function often lead to devastating neurodevelopmental disorders. We have identified two toddlers with different heterozygous missense mutations of the same, and highly conserved, glycine residue located in the ligand-binding-domain of : G689C and G689S. Structure simulations suggest severely impaired glutamate binding, which we confirm by functional analysis. Both variants show three orders of magnitude reductions in glutamate EC, with G689S exhibiting the largest reductions observed for (~2000-fold). Moreover, variants multimerize with, and upregulate, GluN2B-subunits, thus engendering a strong dominant-negative effect on mixed channels. In neurons, overexpression of the variants instigates suppression of synaptic GluNRs. Lastly, while exploring spermine potentiation as a potential treatment, we discovered that the variants fail to respond due to G689's novel role in proton-sensing. Together, we describe two unique variants with extreme effects on channel function. We employ protein-stability measures to explain why current (and future) LBD mutations in GluN2B primarily instigate Loss-of-Function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7554/eLife.67555DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8260228PMC
July 2021

Adult phenotype of encephalopathy.

J Med Genet 2021 Apr 2. Epub 2021 Apr 2.

Neurology Department, University Hospital Antwerp, Antwerp, Belgium

Background: Pathogenic variants are a frequent cause of developmental and epileptic encephalopathy.

Methods: We recruited 13 adults (between 18 years and 45 years of age) with encephalopathy and reviewed their clinical, EEG, neuroimaging and treatment history.

Results: While most patients had daily seizures at seizure onset, seizure frequency declined or remitted during childhood and adulthood. The most common seizure type was tonic seizures (early) infancy, and tonic-clonic and focal impaired awareness seizures later in life. Ten individuals (77%) were seizure-free at last follow-up. In 38% of the individuals, earlier periods of seizure freedom lasting a minimum of 2 years followed by seizure recurrence had occurred. Of the 10 seizure-free patients, 4 were receiving a single antiseizure medication (ASM, carbamazepine, lamotrigine or levetiracetam), and 2 had stopped taking ASM. Intellectual disability (ID) ranged from mild to profound, with the majority (54%) of individuals in the severe category. At last contact, six individuals (46%) remained unable to walk independently, six (46%) had limb spasticity and four (31%) tetraparesis/tetraplegia. Six (46%) remained non-verbal, 10 (77%) had autistic features/autism, 4 (31%) exhibited aggressive behaviour and 4 (31%) destructive behaviour with self-injury. Four patients had visual problems, thought to be related to prematurity in one. Sleep problems were seen in six (46%) individuals.

Conclusion: Seizure frequency declines over the years and most patients are seizure-free in adulthood. Longer seizure-free periods followed by seizure recurrence are common during childhood and adolescence. Most adult patients have severe ID. Motor, language and behavioural problems are an issue of continuous concern.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/jmedgenet-2020-107449DOI Listing
April 2021

Deciphering the premature mortality in PIGA-CDG - An untold story.

Epilepsy Res 2021 Feb 9;170:106530. Epub 2020 Dec 9.

Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Centre, Dianalund, Denmark; Department for Regional Health Services, University of Southern Denmark, Odense, Denmark.

Objective: Congenital disorder of glycosylation (CDG) due to a defective phosphatidylinositol glycan anchor biosynthesis class A protein (PIGA) is a severe X-linked developmental and epileptic encephalopathy. Seizures are often treatment refractory, and patients have intellectual disability and global developmental delay. Previous reports have suggested that patients with PIGA-CDG have a high risk of premature mortality. This study aimed to evaluate the observed high mortality and the causes of death in PIGA-CDG patients.

Methods: We reviewed the literature and collected additional unpublished patients through an international network.

Results: In total, we reviewed the data of 88 patients of whom 30 patients born alive were deceased, and the overall mortality before the age of 20 years was 30 % (26/88). Age at death ranged from 15 days to 48 years of life. The median age at death was two years and more than half of the patients deceased in early childhood. The PIGA-specific mortality rate/1000 person-years was 44.9/1000 person-years (95 %, CI 31.4-64.3). There were no cases of definite or probable sudden unexpected death in epilepsy (SUDEP) and half of the patients died due to respiratory failure (15/30, 50 %) or possible SUDEP (3/30, 10 %). Three patients (10 %) died from severe cardiomyopathy, liver failure and gastrointestinal bleeding, respectively. The cause of death was unclassified in nine patients (30 %). Autopsies were rarely performed and the true cause of death remains unknown for the majority of patients.

Significance: Our data indicate an increased risk of premature death in patients with PIGA-CDG when compared to most monogenic developmental and epileptic encephalopathies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.eplepsyres.2020.106530DOI Listing
February 2021

Current knowledge of SLC6A1-related neurodevelopmental disorders.

Brain Commun 2020 13;2(2):fcaa170. Epub 2020 Oct 13.

Genomic Medicine Institute, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44195, USA.

Advances in gene discovery have identified genetic variants in the solute carrier family 6 member 1 gene as a monogenic cause of neurodevelopmental disorders, including epilepsy with myoclonic atonic seizures, autism spectrum disorder and intellectual disability. The solute carrier family 6 member 1 gene encodes for the GABA transporter protein type 1, which is responsible for the reuptake of the neurotransmitter GABA, the primary inhibitory neurotransmitter in the central nervous system, from the extracellular space. GABAergic inhibition is essential to counterbalance neuronal excitation, and when significantly disrupted, it negatively impacts brain development leading to developmental differences and seizures. Aggregation of patient variants and observed clinical manifestations expand understanding of the genotypic and phenotypic spectrum of this disorder. Here, we assess genetic and phenotypic features in 116 individuals with solute carrier family 6 member 1 variants, the vast majority of which are likely to lead to GABA transporter protein type 1 loss-of-function. The knowledge acquired will guide therapeutic decisions and the development of targeted therapies that selectively enhance transporter function and may improve symptoms. We analysed the longitudinal and cell type-specific expression of solute carrier family 6 member 1 in humans and localization of patient and control missense variants in a novel GABA transporter protein type 1 protein structure model. In this update, we discuss the progress made in understanding and treating solute carrier family 6 member 1-related disorders thus far, through the concerted efforts of clinicians, scientists and family support groups.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/braincomms/fcaa170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7677605PMC
October 2020

Predicting functional effects of missense variants in voltage-gated sodium and calcium channels.

Sci Transl Med 2020 08;12(556)

Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA 02114, USA.

Malfunctions of voltage-gated sodium and calcium channels (encoded by and family genes, respectively) have been associated with severe neurologic, psychiatric, cardiac, and other diseases. Altered channel activity is frequently grouped into gain or loss of ion channel function (GOF or LOF, respectively) that often corresponds not only to clinical disease manifestations but also to differences in drug response. Experimental studies of channel function are therefore important, but laborious and usually focus only on a few variants at a time. On the basis of known gene-disease mechanisms of 19 different diseases, we inferred LOF ( = 518) and GOF ( = 309) likely pathogenic variants from the disease phenotypes of variant carriers. By training a machine learning model on sequence- and structure-based features, we predicted LOF or GOF effects [area under the receiver operating characteristics curve (ROC) = 0.85] of likely pathogenic missense variants. Our LOF versus GOF prediction corresponded to molecular LOF versus GOF effects for 87 functionally tested variants in and (ROC = 0.73) and was validated in exome-wide data from 21,703 cases and 128,957 controls. We showed respective regional clustering of inferred LOF and GOF nucleotide variants across the alignment of the entire gene family, suggesting shared pathomechanisms in the family genes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1126/scitranslmed.aay6848DOI Listing
August 2020

Genetic testing in adult epilepsy patients: A call to action for clinicians.

Epilepsia 2020 09 12;61(9):2055-2056. Epub 2020 Aug 12.

Department of Epilepsy Genetics and Personalized Treatment, Danish Epilepsy Center, Dianalund, Denmark.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/epi.16639DOI Listing
September 2020

Utility of genetic testing for therapeutic decision-making in adults with epilepsy.

Epilepsia 2020 06 19;61(6):1234-1239. Epub 2020 May 19.

Department of Epilepsy Genetics and Personalized Treatment, Danish Epilepsy Center, Dianalund, Denmark.

Objective: Genetic testing has become a routine part of the diagnostic workup in children with early onset epilepsies. In the present study, we sought to investigate a cohort of adult patients with epilepsy, to determinate the diagnostic yield and explore the gain of personalized treatment approaches in adult patients.

Methods: Two hundred patients (age span = 18-80 years) referred for diagnostic gene panel testing at the Danish Epilepsy Center were included. The vast majority (91%) suffered from comorbid intellectual disability. The medical records of genetically diagnosed patients were mined for data on epilepsy syndrome, cognition, treatment changes, and seizure outcome following the genetic diagnosis.

Results: We found a genetic diagnosis in 46 of 200 (23%) patients. SCN1A, KCNT1, and STXBP1 accounted for the greatest number of positive findings (48%). More rare genetic findings included SLC2A1, ATP6A1V, HNRNPU, MEF2C, and IRF2BPL. Gene-specific treatment changes were initiated in 11 of 46 (17%) patients (one with SLC2A1, 10 with SCN1A) following the genetic diagnosis. Ten patients improved, with seizure reduction and/or increased alertness and general well-being.

Significance: With this study, we show that routine diagnostic testing is highly relevant in adults with epilepsy. The diagnostic yield is similar to previously reported pediatric cohorts, and the genetic findings can be useful for therapeutic decision-making, which may lead to better seizure control, ultimately improving quality of life.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/epi.16533DOI Listing
June 2020

Expanding the clinical and EEG spectrum of CNKSR2-related encephalopathy with status epilepticus during slow sleep (ESES).

Clin Neurophysiol 2020 05 13;131(5):1030-1039. Epub 2020 Feb 13.

Danish Epilepsy Centre, Dianalund, Denmark; University of Copenhagen, Copenhagen, Denmark. Electronic address:

Objective: To investigate the clinical and EEG features of Encephalopathy with Status Epilepticus during slow Sleep (ESES) related to CNKSR2 pathogenic variants.

Methods: Detailed clinical history, repeated wakefulness/overnight sleep EEGs, brain MRI were collected in five patients, including one female, with CNKSR2-related ESES.

Results: Neurodevelopment in infancy was normal in two patients, delayed in three. Epilepsy onset (age range: 2-6 years) was associated with appearance or aggravation of cognitive impairment, language regression and/or behavioral disorders. Worsening of epilepsy and of cognitive/behavioral disturbances paralleled by enhancement of non-rapid eye movement (NREM) sleep-related, frontally predominant, EEG epileptic discharges [spike-wave-index (SWI): range 60-96%] was consistent with ESES. In three patients, episodes of absence status epilepticus or aggravation of atypical absences occurred, in this latter case associated with striking increment of awake SWI. Speech/oro-motor dyspraxia was diagnosed in four patients. In two patients, long-term follow-up showed epilepsy remission and persistence of mild/moderate cognitive disorders and behavioral disturbances into adulthood.

Conclusions: Novel findings of our study are occurrence also in females, normal neurodevelopment before epilepsy onset, epilepsy aggravation associated with enhanced awake SWI, mild/moderate evolution in adulthood and language disorder due to speech/oro-motor dyspraxia.

Significance: Our findings expand the phenotypic spectrum of CNKSR2-related ESES.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2020.01.020DOI Listing
May 2020

Biological concepts in human sodium channel epilepsies and their relevance in clinical practice.

Epilepsia 2020 03 23;61(3):387-399. Epub 2020 Feb 23.

Stanley Center for Psychiatric Research, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts.

Objective: Voltage-gated sodium channels (SCNs) share similar amino acid sequence, structure, and function. Genetic variants in the four human brain-expressed SCN genes SCN1A/2A/3A/8A have been associated with heterogeneous epilepsy phenotypes and neurodevelopmental disorders. To better understand the biology of seizure susceptibility in SCN-related epilepsies, our aim was to determine similarities and differences between sodium channel disorders, allowing us to develop a broader perspective on precision treatment than on an individual gene level alone.

Methods: We analyzed genotype-phenotype correlations in large SCN-patient cohorts and applied variant constraint analysis to identify severe sodium channel disease. We examined temporal patterns of human SCN expression and correlated functional data from in vitro studies with clinical phenotypes across different sodium channel disorders.

Results: Comparing 865 epilepsy patients (504 SCN1A, 140 SCN2A, 171 SCN8A, four SCN3A, 46 copy number variation [CNV] cases) and analysis of 114 functional studies allowed us to identify common patterns of presentation. All four epilepsy-associated SCN genes demonstrated significant constraint in both protein truncating and missense variation when compared to other SCN genes. We observed that age at seizure onset is related to SCN gene expression over time. Individuals with gain-of-function SCN2A/3A/8A missense variants or CNV duplications share similar characteristics, most frequently present with early onset epilepsy (<3 months), and demonstrate good response to sodium channel blockers (SCBs). Direct comparison of corresponding SCN variants across different SCN subtypes illustrates that the functional effects of variants in corresponding channel locations are similar; however, their clinical manifestation differs, depending on their role in different types of neurons in which they are expressed.

Significance: Variant function and location within one channel can serve as a surrogate for variant effects across related sodium channels. Taking a broader view on precision treatment suggests that in those patients with a suspected underlying genetic epilepsy presenting with neonatal or early onset seizures (<3 months), SCBs should be considered.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/epi.16438DOI Listing
March 2020

Defining and expanding the phenotype of -associated developmental epileptic encephalopathy.

Neurol Genet 2019 Dec 10;5(6):e373. Epub 2019 Dec 10.

Department of Epilepsy Genetics and Precision Medicine (K.J.M., E.G., G.R., R.S.M.), The Danish Epilepsy Centre Filadelfia, Dianalund, Denmark; Institute for Regional Health Services (K.J.M., E.G., R.S.M.), University of Southern Denmark, Odense; Institute of Human Genetics (D.M., R. Jamra, A.F., J.R.L.), University of Leipzig Medical Center, Germany; Institute of Structural Biology (R. Janowski, D.N.), Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany; Department of Paediatric Radiology (C.R.), University of Leipzig Medical Center, Germany; Department of Epilepsy, Sleep and Pediatric Neurophysiology (J.T.), Lyon University Hospital, France; Neuropediatric Unit (A.-L.P., D.M.V., G.L.), Lyon University Hospital, France; Department of Medical Genetics (N.C., G.L.), Lyon University Hospital, France; GenDev Team (N.C.), CNRS UMR 5292, INSERM U1028, CNRL and University of Lyon, France; Department of Genetics (E.B.), University Medical Center Utrecht, The Netherlands; Department of Child Neurology (K.G.), Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands; Department of Paediatrics (A.P.B.), Copenhagen University Hospital Rigshospitalet, Denmark; Baylor College of Medicine (S.M., K.N.), Children's Hospital of San Antonio; Undiagnosed Diseases Program (G.B., C.P.), Genetic Services of Western Australia, Department of Health, Government of Western Australia, Perth; Western Australian Register of Developmental Anomalies (G.B., D.G.), Australia; Telethon Kids Institute and the School of Paediatrics and Child Health (G.B.), University of Western Australia, Perth; Linear Clinical Research (L.D.), WA, Australia; Center of Human Genetics (S.S), Jena University Hospital, Germany; Department of Neuropediatrics (A.D.), Jena University Hospital, Germany; Division of Neurology (K.L.H.), Children's Hospital of Philadelphia, PA; Division of Neuropediatrics (A.M.), University of Leipzig Medical Center, Germany; Amplexa Genetics (H.H.), Odense, Denmark; Clinic for Children (H.H.), Værløse, Denmark; Center for Integrative Brain Research (G.M.), Seattle Children's Research Institute, WA; Department of Pediatrics (G.M.), University of Washington, Seattle; Medical Genetics Unit (F.B.), Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy; Istituto Dermopatico dell'Immacolata (F.B.), IDI-IRCCS, Rome, Italy; Institute of Human Genetics (T.B., M.H.), University Medical Center Hamburg-Eppendorf, Germany; Childrens Hospital (J.D.), University Medical Center Hamburg-Eppendorf, Germany; University of Copenhagen (G.R.), Denmark; Institute for Human Genetics (P.M.), University Hospital Magdeburg, Germany; Children's Hospital A. Meyer (R.G., A.V.), University of Florence, Italy; and Institute of Pharmaceutical Biotechnology (D.N.), Ulm University, Germany.

Objective: The study is aimed at widening the clinical and genetic spectrum and at assessing genotype-phenotype associations in encephalopathy.

Methods: Through diagnostic gene panel screening in an epilepsy cohort, and recruiting through GeneMatcher and our international network, we collected 10 patients with biallelic 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.

Results: Biallelic pathogenic variants in 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.

Conclusions: These data revealed first genotype-phenotype associations and may serve for improved interpretation of new variants and well-founded genetic counseling.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1212/NXG.0000000000000373DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6927360PMC
December 2019

Biallelic inherited SCN8A variants, a rare cause of SCN8A-related developmental and epileptic encephalopathy.

Epilepsia 2019 11 17;60(11):2277-2285. Epub 2019 Oct 17.

Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Centre, Dianalund, Denmark.

Objective: Monoallelic de novo gain-of-function variants in the voltage-gated sodium channel SCN8A are one of the recurrent causes of severe developmental and epileptic encephalopathy (DEE). In addition, a small number of de novo or inherited monoallelic loss-of-function variants have been found in patients with intellectual disability, autism spectrum disorder, or movement disorders. Inherited monoallelic variants causing either gain or loss-of-function are also associated with less severe conditions such as benign familial infantile seizures and isolated movement disorders. In all three categories, the affected individuals are heterozygous for a SCN8A variant in combination with a wild-type allele. In the present study, we describe two unusual families with severely affected individuals who inherited biallelic variants of SCN8A.

Methods: We identified two families with biallelic SCN8A variants by diagnostic gene panel sequencing. Functional analysis of the variants was performed using voltage clamp recordings from transfected ND7/23 cells.

Results: We identified three probands from two unrelated families with DEE due to biallelic SCN8A variants. Each parent of an affected individual carried a single heterozygous SCN8A variant and exhibited mild cognitive impairment without seizures. In both families, functional analysis demonstrated segregation of one allele with complete loss-of-function, and one allele with altered biophysical properties consistent with partial loss-of-function.

Significance: These studies demonstrate that SCN8A DEE may, in rare cases, result from inheritance of two variants, both of which exhibit reduced channel activity. In these families, heterozygosity for the dominant variants results in less severe disease than biallelic inheritance of two variant alleles. The clinical consequences of variants with partial and complete loss of SCN8A function are variable and likely to be influenced by genetic background.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/epi.16371DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6842408PMC
November 2019

The spectrum of intermediate SCN8A-related epilepsy.

Epilepsia 2019 05 10;60(5):830-844. Epub 2019 Apr 10.

Neuroscience Department, Children's Hospital Anna Meyer, University of Florence, Florence, Italy.

Objective: Pathogenic variants in SCN8A have been associated with a wide spectrum of epilepsy phenotypes, ranging from benign familial infantile seizures (BFIS) to epileptic encephalopathies with variable severity. Furthermore, a few patients with intellectual disability (ID) or movement disorders without epilepsy have been reported. The vast majority of the published SCN8A patients suffer from severe developmental and epileptic encephalopathy (DEE). In this study, we aimed to provide further insight on the spectrum of milder SCN8A-related epilepsies.

Methods: A cohort of 1095 patients were screened using a next generation sequencing panel. Further patients were ascertained from a network of epilepsy genetics clinics. Patients with severe DEE and BFIS were excluded from the study.

Results: We found 36 probands who presented with an SCN8A-related epilepsy and normal intellect (33%) or mild (61%) to moderate ID (6%). All patients presented with epilepsy between age 1.5 months and 7 years (mean = 13.6 months), and 58% of these became seizure-free, two-thirds on monotherapy. Neurological disturbances included ataxia (28%) and hypotonia (19%) as the most prominent features. Interictal electroencephalogram was normal in 41%. Several recurrent variants were observed, including Ile763Val, Val891Met, Gly1475Arg, Gly1483Lys, Phe1588Leu, Arg1617Gln, Ala1650Val/Thr, Arg1872Gln, and Asn1877Ser.

Significance: With this study, we explore the electroclinical features of an intermediate SCN8A-related epilepsy with mild cognitive impairment, which is for the majority a treatable epilepsy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/epi.14705DOI Listing
May 2019

From next-generation sequencing to targeted treatment of non-acquired epilepsies.

Expert Rev Mol Diagn 2019 03 4;19(3):217-228. Epub 2019 Feb 4.

a Department of Epilepsy Genetics and Precision Medicine , The Danish Epilepsy Centre , Dianalund , Denmark.

Introduction: Within the last decade, next-generation sequencing (NGS) has resulted in remarkable advances in the field of epilepsy genetics. NGS has become a routine part of the diagnostic workup in many countries. A workup that has led to higher diagnostic yields and insights into the underlying disease mechanisms. Areas covered: In this review, we report on the recent contributions of NGS testing to the diagnosis and the understanding of pathophysiological mechanisms, phenotypic variability, and genetic heterogeneity of different epilepsies including developmental and/or epileptic encephalopathies, focal and generalized epilepsies. Furthermore, we discuss how the increased knowledge of the genetic architecture of the epilepsies can be translated into more personalized treatment. Expert opinion/commentary: Targeted gene panels or whole exome sequencing can provide a genetic diagnosis for up to 30% of the patients with early-onset epilepsy. Despite current technical limitations, NGS-based technologies can become the new first-tier diagnostic tests in the epilepsies. As the pool of genetically diagnosed patients has increased, so has the demand for more accurate treatment. Approximately 25% of the epilepsy patients with de novo mutations have genetic diagnoses with potential targets for precision medicine approaches, thus illustrating the enormous utility of genetic testing for therapeutic decision-making.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/14737159.2019.1573144DOI Listing
March 2019

Neuronal mechanisms of mutations in SCN8A causing epilepsy or intellectual disability.

Brain 2019 02;142(2):376-390

Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Tuebingen, Germany.

Ion channel mutations can cause distinct neuropsychiatric diseases. We first studied the biophysical and neurophysiological consequences of four mutations in the human Na+ channel gene SCN8A causing either mild (E1483K) or severe epilepsy (R1872W), or intellectual disability and autism without epilepsy (R1620L, A1622D). Only combined electrophysiological recordings of transfected wild-type or mutant channels in both neuroblastoma cells and primary cultured neurons revealed clear genotype-phenotype correlations. The E1483K mutation causing mild epilepsy showed no significant biophysical changes, whereas the R1872W mutation causing severe epilepsy induced clear gain-of-function biophysical changes in neuroblastoma cells. However, both mutations increased neuronal firing in primary neuronal cultures. In contrast, the R1620L mutation associated with intellectual disability and autism-but not epilepsy-reduced Na+ current density in neuroblastoma cells and expectedly decreased neuronal firing. Interestingly, for the fourth mutation, A1622D, causing severe intellectual disability and autism without epilepsy, we observed a dramatic slowing of fast inactivation in neuroblastoma cells, which induced a depolarization block in neurons with a reduction of neuronal firing. This latter finding was corroborated by computational modelling. In a second series of experiments, we recorded three more mutations (G1475R, M1760I, G964R, causing intermediate or severe epilepsy, or intellectual disability without epilepsy, respectively) that revealed similar results confirming clear genotype-phenotype relationships. We found intermediate or severe gain-of-function biophysical changes and increases in neuronal firing for the two epilepsy-causing mutations and decreased firing for the loss-of-function mutation causing intellectual disability. We conclude that studies in neurons are crucial to understand disease mechanisms, which here indicate that increased or decreased neuronal firing is responsible for distinct clinical phenotypes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/brain/awy326DOI Listing
February 2019

Differences in mortality in Fusobacterium necrophorum and Fusobacterium nucleatum infections detected by culture and 16S rRNA gene sequencing.

Eur J Clin Microbiol Infect Dis 2019 Jan 29;38(1):75-80. Epub 2018 Oct 29.

Department of Respiratory Medicine, Næstved Hospital, 61 Ringstedgade, DK-4700, Næstved, Denmark.

Fusobacterium species are components of the normal microbiota of the oral cavity, gastrointestinal tract, and female genital tract. They are increasingly recognized as causative agents of oral, laryngeal, and tonsillar infections. Several fusobacterial species are involved in infections, with F. necrophorum and F. nucleatum being the most commonly cultured subtypes. In this study, we aimed to investigate clinical and prognostic differences in terms of mortality and association with malignancy between F. necrophorum and F. nucleatum detected by culture and 16S rRNA gene sequencing. This is a systematic, comparative, retrospective, non-interventional study. Data were extracted from the Department of Clinical Microbiology, Region Zealand, Denmark: all patients with F. necrophorum or F. nucleatum detected by culture or 16S rRNA gene sequencing from 1st of January 2010 to 30th of June 2015 were included. In total, F. necrophorum was detected in samples from 75 patients, and F. nucleatum in samples from 68 patients (total: n = 143). Thirteen patients had a current cancer diagnosis at the time of fusobacterial sampling. Multivariate analyses revealed a significant association of "current cancer" with 30-day mortality. Fusobacterial subtype was not associated with mortality neither in overall nor in subgroups with or without current cancer. Despite differences in clinical disease pattern between F. necrophorum and F. nucleatum, mortality was unaffected by fusobacterial subtype. Mortality was significantly related to comorbidity, especially a current diagnosis of cancer. Our data highlights the current debate whether fusobacterial involvement in cancer may have disease-altering properties, rather than being opportunistic pathogens secondary to cancer disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10096-018-3394-4DOI Listing
January 2019

The phenotype of developmental and epileptic encephalopathy.

Neurology 2018 09 31;91(12):e1112-e1124. Epub 2018 Aug 31.

From the Department of Clinical Neurophysiology (E.G., S.B.), Danish Epilepsy Centre, Dianalund; Institute for Regional Health Services (E.G., K.M.J., R.S.M.), University of Southern Denmark, Odense, Denmark; Neuroscience Department (C.M., R.G., M.M.), Children's Hospital A. Meyer, University of Florence; Department of Neuroscience (M.T., N.S., F.V.), Bambino Gesù Children's Hospital, IRCCS, Rome, Italy; Division of Neurology (M.P.F., I.H.), The Children's Hospital of Philadelphia; Departments of Pediatrics and Neurology (M.P.F., I.H.), Perelman School of Medicine at the University of Pennsylvania, Philadelphia; Universitätskinderklinik Tübingen (M.A., M.W.), Germany; Department of Neurology (K.H.), Royal Children's Hospital Melbourne; Department of Paediatrics (K.H.), University of Melbourne; Australia Neurosciences Group (K.H.), Murdoch Children's Research Institute, Melbourne, Australia; Servizio di Neuropsichiatria Infantile (F.D., E.F.), Policlinico G.B. Rossi, Universita Degli Studi di Verona; Department of Child Neurology (S.S., G.A.), Ospedale Pediatrico G. Salesi-Ospedali Riuniti, Ancona, Italy; Division of Clinical Neurophysiology (B.B.), Children's Research Center, University Children's Hospital Zurich, Switzerland; Brain and Behaviour Department (S.M.), University of Pavia; Department of Pediatric Neuroradiology (A.P.), IRCCS "C. Mondino" National Neurological Institute, Pavia, Italy; Department of Epilepsy Genetics (K.J., R.S.M.), Danish Epilepsy Centre Dianalund; Department of Child Neurology (B.J.), Danish Epilepsy Centre, Dianalund, Denmark; Cytogenetic and Molecular Genetic Laboratory (S.R., F.C.), Istituto Auxologico Italiano, IRCCS, Milano, Italy; Department of Adult Neurology (G.R.), Danish Epilepsy Centre, Dianalund; University of Copenhagen (G.R.), Denmark; Struttura Complessa di Neurologia Pediatrica Ospedale Vittore Buzzi (P.V.), Milano; Dipartimento di Scienze Biomediche e Cliniche L. Sacco (P.V.), Università di Milano, Italy; Århus University (S.B.), Denmark; Department of Child Neurology (I.E.S.), University of Melbourne, Austin Health, Florey Institute; and Department of Child Neurology (I.E.S.), The Royal Children's Hospital, Melbourne, Australia.

Objective: To delineate the electroclinical features of infantile developmental and epileptic encephalopathy (EIEE13, OMIM #614558).

Methods: Twenty-two patients, aged 19 months to 22 years, underwent electroclinical assessment.

Results: Sixteen of 22 patients had mildly delayed development since birth. Drug-resistant epilepsy started at a median age of 4 months, followed by developmental slowing, pyramidal/extrapyramidal signs (22/22), movement disorders (12/22), cortical blindness (17/22), sialorrhea, and severe gastrointestinal symptoms (15/22), worsening during early childhood and plateauing at age 5 to 9 years. Death occurred in 4 children, following extreme neurologic deterioration, at 22 months to 5.5 years. Nonconvulsive status epilepticus recurred in 14 of 22 patients. The most effective antiepileptic drugs were oxcarbazepine, carbamazepine, phenytoin, and benzodiazepines. EEG showed background deterioration, epileptiform abnormalities with a temporo-occipital predominance, and posterior delta/beta activity correlating with visual impairment. Video-EEG documented focal seizures (FS) (22/22), spasm-like episodes (8/22), cortical myoclonus (8/22), and myoclonic absences (1/22). FS typically clustered and were prolonged (<20 minutes) with (1) cyanosis, hypomotor, and vegetative semiology, sometimes unnoticed, followed by (2) tonic-vibratory and (3) (hemi)-clonic manifestations ± evolution to a bilateral tonic-clonic seizure. FS had posterior-temporal/occipital onset, slowly spreading and sometimes migrating between hemispheres. Brain MRI showed progressive parenchymal atrophy and restriction of the optic radiations.

Conclusions: developmental and epileptic encephalopathy has strikingly consistent electroclinical features, suggesting a global progressive brain dysfunction primarily affecting the temporo-occipital regions. Both uncontrolled epilepsy and developmental compromise contribute to the profound impairment (increasing risk of death) during early childhood, but stabilization occurs in late childhood.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1212/WNL.0000000000006199DOI Listing
September 2018

Early mortality in SCN8A-related epilepsies.

Epilepsy Res 2018 07 13;143:79-81. Epub 2018 Apr 13.

The Danish Epilepsy Centre Filadelfia, Dianalund, Denmark; University of Copenhagen, Copenhagen, Denmark. Electronic address:

SCN8A-related epilepsies are often severe developmental and epileptic encephalopathies. Seizures can be treatment resistant, and patients suffer from severe intellectual disability. Reports have suggested that SCN8A-related epilepsies have a high mortality with SUDEP as the major underlying cause. SUDEP is a catastrophic event, and the risk of occurrence should be correctly and carefully discussed with patients and families. We tested the hypothesis of SUDEP as the main cause of death in SCN8A-related epilepsies by reviewing all the currently reported patients with SCN8A. In addition, we collected unpublished patients through an international network. In total, we reviewed the data of 190 patients. In our cohort, 10 patients were deceased, and the overall mortality was 5.3%. Within the ten deceased patients, age at death ranged from 16 months to 17 years; the majority (7/10) of them died in early childhood. Three patients died of probable or definite SUDEP. Thus, our data do not indicate an increased risk when compared to other DEEs. Indeed, death in SCN8A-related epilepsies seems to occur most often in children experiencing a relentless worsening of their epilepsy and neurological condition, rendering them susceptible to pulmonary infections and respiratory distress that ultimately can be fatal.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.eplepsyres.2018.04.008DOI Listing
July 2018

Defining the phenotypic spectrum of SLC6A1 mutations.

Epilepsia 2018 02 8;59(2):389-402. Epub 2018 Jan 8.

Neurology Unit, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.

Objective: Pathogenic SLC6A1 variants were recently described in patients with myoclonic atonic epilepsy (MAE) and intellectual disability (ID). We set out to define the phenotypic spectrum in a larger cohort of SCL6A1-mutated patients.

Methods: We collected 24 SLC6A1 probands and 6 affected family members. Four previously published cases were included for further electroclinical description. In total, we reviewed the electroclinical data of 34 subjects.

Results: Cognitive development was impaired in 33/34 (97%) subjects; 28/34 had mild to moderate ID, with language impairment being the most common feature. Epilepsy was diagnosed in 31/34 cases with mean onset at 3.7 years. Cognitive assessment before epilepsy onset was available in 24/31 subjects and was normal in 25% (6/24), and consistent with mild ID in 46% (11/24) or moderate ID in 17% (4/24). Two patients had speech delay only, and 1 had severe ID. After epilepsy onset, cognition deteriorated in 46% (11/24) of cases. The most common seizure types were absence, myoclonic, and atonic seizures. Sixteen cases fulfilled the diagnostic criteria for MAE. Seven further patients had different forms of generalized epilepsy and 2 had focal epilepsy. Twenty of 31 patients became seizure-free, with valproic acid being the most effective drug. There was no clear-cut correlation between seizure control and cognitive outcome. Electroencephalography (EEG) findings were available in 27/31 patients showing irregular bursts of diffuse 2.5-3.5 Hz spikes/polyspikes-and-slow waves in 25/31. Two patients developed an EEG pattern resembling electrical status epilepticus during sleep. Ataxia was observed in 7/34 cases. We describe 7 truncating and 18 missense variants, including 4 recurrent variants (Gly232Val, Ala288Val, Val342Met, and Gly362Arg).

Significance: Most patients carrying pathogenic SLC6A1 variants have an MAE phenotype with language delay and mild/moderate ID before epilepsy onset. However, ID alone or associated with focal epilepsy can also be observed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/epi.13986DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5912688PMC
February 2018

[Dietary treatment of medically refractory epilepsy in children and adolescents].

Ugeskr Laeger 2017 Apr;179(14)

Ketogenic diet (KD) is used worldwide in the treatment of medically refractory epilepsy. Since the introduction of KD in the early 1900s, new approaches such as medium-chain triglyceride ketogenic diet, modified Atkins diet and low glycaemic index treatment have been suggested as alternative treatments. Several studies have documented significant seizure reduction from all four diets. The aim of this article is to give an overview of the effect of dietary treatment and to discuss advantages in initiating dietary treatment as an early treatment instead of as a last option.
View Article and Find Full Text PDF

Download full-text PDF

Source
April 2017

Genetic and phenotypic heterogeneity suggest therapeutic implications in SCN2A-related disorders.

Brain 2017 May;140(5):1316-1336

CeGaT - Center for Genomics and Transcriptomics, Tübingen, Germany.

Mutations in SCN2A, a gene encoding the voltage-gated sodium channel Nav1.2, have been associated with a spectrum of epilepsies and neurodevelopmental disorders. Here, we report the phenotypes of 71 patients and review 130 previously reported patients. We found that (i) encephalopathies with infantile/childhood onset epilepsies (≥3 months of age) occur almost as often as those with an early infantile onset (<3 months), and are thus more frequent than previously reported; (ii) distinct phenotypes can be seen within the late onset group, including myoclonic-atonic epilepsy (two patients), Lennox-Gastaut not emerging from West syndrome (two patients), and focal epilepsies with an electrical status epilepticus during slow sleep-like EEG pattern (six patients); and (iii) West syndrome constitutes a common phenotype with a major recurring mutation (p.Arg853Gln: two new and four previously reported children). Other known phenotypes include Ohtahara syndrome, epilepsy of infancy with migrating focal seizures, and intellectual disability or autism without epilepsy. To assess the response to antiepileptic therapy, we retrospectively reviewed the treatment regimen and the course of the epilepsy in 66 patients for which well-documented medical information was available. We find that the use of sodium channel blockers was often associated with clinically relevant seizure reduction or seizure freedom in children with early infantile epilepsies (<3 months), whereas other antiepileptic drugs were less effective. In contrast, sodium channel blockers were rarely effective in epilepsies with later onset (≥3 months) and sometimes induced seizure worsening. Regarding the genetic findings, truncating mutations were exclusively seen in patients with late onset epilepsies and lack of response to sodium channel blockers. Functional characterization of four selected missense mutations using whole cell patch-clamping in tsA201 cells-together with data from the literature-suggest that mutations associated with early infantile epilepsy result in increased sodium channel activity with gain-of-function, characterized by slowing of fast inactivation, acceleration of its recovery or increased persistent sodium current. Further, a good response to sodium channel blockers clinically was found to be associated with a relatively small gain-of-function. In contrast, mutations in patients with late-onset forms and an insufficient response to sodium channel blockers were associated with loss-of-function effects, including a depolarizing shift of voltage-dependent activation or a hyperpolarizing shift of channel availability (steady-state inactivation). Our clinical and experimental data suggest a correlation between age at disease onset, response to sodium channel blockers and the functional properties of mutations in children with SCN2A-related epilepsy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/brain/awx054DOI Listing
May 2017

Mutations in GABRB3: From febrile seizures to epileptic encephalopathies.

Neurology 2017 01 4;88(5):483-492. Epub 2017 Jan 4.

From the Danish Epilepsy Centre (R.S.M., K.M.J., M.N.), Dianalund; Institute for Regional Health Services (R.S.M., K.M.J., M.N.), University of Southern Denmark, Odense; Department of Neurology and Epileptology (T.V.W., S.V., H.L., S.M.), Hertie Institute for Clinical Brain Research, and Department of Neurosurgery (T.V.W.), University of Tübingen; Department of Neuropediatrics (I.H., M.P., S.v.S., H.M.), University Medical Center Schleswig-Holstein, Kiel, Germany; Division of Neurology (I.H., S.H., H.D.), The Children's Hospital of Philadelphia, PA; Neuroscience Department (C.M., R.G.), Children's Hospital Anna Meyer-University of Florence, Italy; Department of Genetics (E.H.B., M.S., K.L.v.G.), University Medical Center Utrecht, the Netherlands; Department of Neurology and Neurorehabilitation (U.V., I.T., T.T.), Children's Clinic of Tartu University Hospital, Estonia; Department of Pediatric Neurology and Epilepsy Center (I.B.), LMU Munich, Germany; Department of Pediatrics (I.T., T.T.), University of Tartu; Tallinn Children's Hospital (I.T.), Tallinn, Estonia; Clinic for Neuropediatrics and Neurorehabilitation (G.K., C.B., H.H.), Epilepsy Center for Children and Adolescents, Schön Klinik Vogtareuth, Germany; Paracelsus Medical Private University (G.K.), Salzburg, Austria; Neuropeadiatric Department (L.L.F.), Hospices Civils de Lyon; Department of Genetics (G.L., N.C.), Lyon University Hospitals; Claude Bernard Lyon I University (G.L., N.C.); Lyon Neuroscience Research Centre (G.L., N.C.), CNRS UMR5292, INSERM U1028; Epilepsy, Sleep and Pediatric Neurophysiology Department (J.d.B.), Lyon University Hospitals, France; Clinic for Pediatric Neurology (S.B.), Pediatric Department, University Hospital, Herlev, Denmark; Kleinwachau (N.H.), Sächsisches Epilepsiezentrum Radeberg, Dresden; Department of Neuropediatrics/Epilepsy Center (J.J.), University Medical Center Freiburg; Department of General Paediatrics (S.S.), Division of Child Neurology and Inherited Metabolic Diseases, Centre for Paediatrics and Adolescent Medicine, University Hospital Heidelberg; Department of Women and Child Health (S.S.), Hospital for Children and Adolescents, University of Leipzig Hospitals and Clinics, Germany; Department of Pediatrics (C.T.M., H.C.M.), Division of Genetic Medicine, University of Washington, Seattle; Amplexa Genetics (L.H.G.L., H.A.D.), Odense, Denmark; Northern German Epilepsy Center for Children and Adolescents (S.v.S.), Schwentinental-Raisdorf, Germany; Wilhelm Johannsen Centre for Functional Genome Research (Y.M., N.T.), Department of Cellular and Molecular Medicine, University of Copenhagen; Danish Epilepsy Center (G.R.), Filadelfia/University of Copenhagen, Denmark; Department of Diagnostics (J.R.L.), Institute of Human Genetics, University of Leipzig; and Svt. Luka's Institute of Child Neurology and Epilepsy (K.M.), Moscow, Russia. Dr Maljevic is currently at the Florey Institute of Neuroscience and Mental Health, Melbourne, Australia.

Objective: To examine the role of mutations in GABRB3 encoding the β subunit of the GABA receptor in individual patients with epilepsy with regard to causality, the spectrum of genetic variants, their pathophysiology, and associated phenotypes.

Methods: We performed massive parallel sequencing of GABRB3 in 416 patients with a range of epileptic encephalopathies and childhood-onset epilepsies and recruited additional patients with epilepsy with GABRB3 mutations from other research and diagnostic programs.

Results: We identified 22 patients with heterozygous mutations in GABRB3, including 3 probands from multiplex families. The phenotypic spectrum of the mutation carriers ranged from simple febrile seizures, genetic epilepsies with febrile seizures plus, and epilepsy with myoclonic-atonic seizures to West syndrome and other types of severe, early-onset epileptic encephalopathies. Electrophysiologic analysis of 7 mutations in Xenopus laevis oocytes, using coexpression of wild-type or mutant β, together with α and γ subunits and an automated 2-microelectrode voltage-clamp system, revealed reduced GABA-induced current amplitudes or GABA sensitivity for 5 of 7 mutations.

Conclusions: Our results indicate that GABRB3 mutations are associated with a broad phenotypic spectrum of epilepsies and that reduced receptor function causing GABAergic disinhibition represents the relevant disease mechanism.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1212/WNL.0000000000003565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5278942PMC
January 2017

Gene Panel Testing in Epileptic Encephalopathies and Familial Epilepsies.

Mol Syndromol 2016 Sep 20;7(4):210-219. Epub 2016 Aug 20.

Danish Epilepsy Centre, Filadelfia, Dianalund, Denmark.

In recent years, several genes have been causally associated with epilepsy. However, making a genetic diagnosis in a patient can still be difficult, since extensive phenotypic and genetic heterogeneity has been observed in many monogenic epilepsies. This study aimed to analyze the genetic basis of a wide spectrum of epilepsies with age of onset spanning from the neonatal period to adulthood. A gene panel targeting 46 epilepsy genes was used on a cohort of 216 patients consecutively referred for panel testing. The patients had a range of different epilepsies from benign neonatal seizures to epileptic encephalopathies (EEs). Potentially causative variants were evaluated by literature and database searches, submitted to bioinformatic prediction algorithms, and validated by Sanger sequencing. If possible, parents were included for segregation analysis. We identified a presumed disease-causing variant in 49 (23%) of the 216 patients. The variants were found in 19 different genes including and . Patients with neonatal-onset epilepsies had the highest rate of positive findings (57%). The overall yield for patients with EEs was 32%, compared to 17% among patients with generalized epilepsies and 16% in patients with focal or multifocal epilepsies. By the use of a gene panel consisting of 46 epilepsy genes, we were able to find a disease-causing genetic variation in 23% of the analyzed patients. The highest yield was found among patients with neonatal-onset epilepsies and EEs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1159/000448369DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5073625PMC
September 2016

Lemierre's syndrome: current perspectives on diagnosis and management.

Infect Drug Resist 2016 14;9:221-227. Epub 2016 Sep 14.

Department of Lung Medicine, Naestved Hospital, Naestved; Institute for Regional Health Research, University of Southern Denmark, Odense; Department of Pulmonology, Zealand University Hospital, Roskilde, Denmark.

This is a systematic review of cases with Lemierre's syndrome (LS) in the past 5 years. LS is characterized by sepsis often evolving after a sore throat or tonsillitis and then complicated by various septic emboli and thrombosis of the internal jugular vein. Symptoms include sepsis, pain, and/or swelling in the throat or neck, as well as respiratory symptoms. Laboratory findings show elevated infectious parameters and radiological findings show thrombosis of the internal jugular vein and emboli in the lungs or other organs. The syndrome is often associated with an infection with We found a total of 137 cases of LS, of which 47 were infected with and others with and . Complications of this rare but severe disease included osteomyelitis, meningitis, and acute respiratory distress syndrome. Mortality was extremely high in the pre-antibiotic era but has diminished with the advent of antibiotics. This review showed a mortality rate of only 2% of which none of the cases involved fusobacteria. Duration of treatment varied; a 4-6-week course of carbapenem or piperacillin/tazobactam in combination with metronidazole was optimum. Other treatment options included anticoagulants in 46% of cases, which is unwarrantedly high, as to date, no evidence of the positive effects of anticoagulants in LS exists. Only two cases had ligation of the internal jugular vein performed. This review confirms the rare, but severe aspects of LS. Mortality from LS in this day and age appears to be low, however the syndrome is difficult to recognize, and still requires the full attention of the clinician.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2147/IDR.S95050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5028102PMC
September 2016

Letter to the editor: confirming neonatal seizure and late onset ataxia in SCN2A Ala263Val.

J Neurol 2016 Jul 9;263(7):1459-60. Epub 2016 May 9.

The Danish Epilepsy Centre, Filadelfia, 4293, Dianalund, Denmark.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00415-016-8149-5DOI Listing
July 2016

Precision Medicine: SCN8A Encephalopathy Treated with Sodium Channel Blockers.

Neurotherapeutics 2016 Jan;13(1):190-1

The Danish Epilepsy Centre Filadelfia, Dianalund, Denmark.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s13311-015-0403-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4720666PMC
January 2016
-->