Publications by authors named "Eva Andermann"

70 Publications

Progressive myoclonus epilepsies-Residual unsolved cases have marked genetic heterogeneity including dolichol-dependent protein glycosylation pathway genes.

Am J Hum Genet 2021 04;108(4):722-738

Neurology - Neurophysiology Unit, ASST dei Sette Laghi, Galmarini Tradate Hospital, Tradate 21049, Italy.

Progressive myoclonus epilepsies (PMEs) comprise a group of clinically and genetically heterogeneous rare diseases. Over 70% of PME cases can now be molecularly solved. Known PME genes encode a variety of proteins, many involved in lysosomal and endosomal function. We performed whole-exome sequencing (WES) in 84 (78 unrelated) unsolved PME-affected individuals, with or without additional family members, to discover novel causes. We identified likely disease-causing variants in 24 out of 78 (31%) unrelated individuals, despite previous genetic analyses. The diagnostic yield was significantly higher for individuals studied as trios or families (14/28) versus singletons (10/50) (OR = 3.9, p value = 0.01, Fisher's exact test). The 24 likely solved cases of PME involved 18 genes. First, we found and functionally validated five heterozygous variants in NUS1 and DHDDS and a homozygous variant in ALG10, with no previous disease associations. All three genes are involved in dolichol-dependent protein glycosylation, a pathway not previously implicated in PME. Second, we independently validate SEMA6B as a dominant PME gene in two unrelated individuals. Third, in five families, we identified variants in established PME genes; three with intronic or copy-number changes (CLN6, GBA, NEU1) and two very rare causes (ASAH1, CERS1). Fourth, we found a group of genes usually associated with developmental and epileptic encephalopathies, but here, remarkably, presenting as PME, with or without prior developmental delay. Our systematic analysis of these cases suggests that the small residuum of unsolved cases will most likely be a collection of very rare, genetically heterogeneous etiologies.
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http://dx.doi.org/10.1016/j.ajhg.2021.03.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8059372PMC
April 2021

Comparative analysis of the safety and tolerability of eslicarbazepine acetate in older (≥60 years) and younger (18-59 years) adults.

Epilepsy Res 2021 01 10;169:106478. Epub 2020 Oct 10.

Sunovion Pharmaceuticals Inc., Marlborough, MA, USA. Electronic address:

Objective: To investigate the safety and tolerability of eslicarbazepine acetate (ESL), a once-daily oral anti-seizure drug (ASD), in older and younger adult patient populations.

Methods: Two post-hoc pooled data analyses were performed: one from three Phase III studies in patients with focal (partial-onset) seizures who were taking 1-3 concomitant ASDs; the other from five Phase II studies in patients from non-epilepsy populations not taking other ASDs chronically and/or at a clinically-effective anti-seizure dose. The frequencies of treatment-emergent adverse events (TEAEs) were calculated for the older (≥60 years) and younger (18-59 years) adults separately.

Results: In the focal seizures study pool, 4.1 % of patients (58/1431) were aged ≥60 years. The overall frequency of TEAEs was 77.5 % in older ESL-treated patients and 72.6 % in younger ESL-treated patients (p = 0.495). For patients who received placebo, the overall frequency of TEAEs was 50.0 % in the older adults and 57.5 % in the younger adults (p = 0.531). The overall placebo-adjusted frequency of TEAEs was 27.5 % in older adults and 15.1 % in younger adults. The placebo-adjusted frequencies of the TEAEs dizziness, somnolence, headache, nausea, diplopia, blurred vision, and ataxia were ≥5 % higher, and frequencies of vomiting and vertigo were ≥2 % higher in older than younger adults. The overall frequency of TEAEs leading to discontinuation was 15.0 % in older ESL-treated patients and 17.6 % in younger ESL-treated patients (p = 0.647); the frequency increased with increasing ESL dose. For patients who received placebo, the overall frequency of TEAEs leading to discontinuation was 5.6 % in older adults and 6.6 % in younger adults (p = 0.847). In the non-epilepsy study pool, 30.2 % of patients (515/1705) were aged ≥60 years. The overall frequency of TEAEs was 56.9 % in older ESL-treated patients and 58.8 % in younger ESL-treated patients. The placebo-adjusted frequencies were 14.9 % in older and 15.1 % in younger ESL-treated patients. The placebo-adjusted frequencies of the TEAEs nausea, vomiting, fatigue, and vertigo were ≥2 % higher in older adults, whereas somnolence was ≥2 % higher in younger adults. The overall frequency of TEAEs leading to discontinuation was 18.3 % in older ESL-treated patients and 12.1 % in younger ESL-treated patients (p = 0.003); frequencies were not related to ESL dose. For patients who received placebo, the overall frequency of TEAEs leading to discontinuation was 8.0 % in older adults and 5.6 % in younger adults (p = 0.407).

Conclusion: Analyses of adverse event data support the safety and tolerability of ESL in adults aged ≥60 years. In the limited number of older patients with focal seizures taking ESL plus concomitant ASDs (n = 40), the frequency of TEAEs was generally higher than in younger adults. However, in the non-epilepsy patient group (in which the number of older patients was ten times larger; 427 patients taking ESL without concomitant ASDs), no marked age-related TEAE differences were observed, suggesting that increased ASD load associated with adjunctive therapy may complicate treatment selection in older patients, due to risk of increased adverse events. As is common practice for all ASDs, balancing clinical response and tolerability is needed in this vulnerable group of patients.
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http://dx.doi.org/10.1016/j.eplepsyres.2020.106478DOI Listing
January 2021

Autosomal-dominant adult neuronal ceroid lipofuscinosis caused by duplication in DNAJC5 initially missed by Sanger and whole-exome sequencing.

Eur J Hum Genet 2020 06 9;28(6):783-789. Epub 2020 Jan 9.

Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic.

Adult-onset neuronal ceroid lipofuscinoses (ANCL, Kufs disease) are rare hereditary neuropsychiatric disorders characterized by intralysosomal accumulation of ceroid in tissues. The ceroid accumulation primarily affects the brain, leading to neuronal loss and progressive neurodegeneration. Although several causative genes have been identified (DNAJC5, CLN6, CTSF, GRN, CLN1, CLN5, ATP13A2), the genetic underpinnings of ANCL in some families remain unknown. Here we report one family with autosomal dominant (AD) Kufs disease caused by a 30 bp in-frame duplication in DNAJC5, encoding the cysteine-string protein alpha (CSPα). This variant leads to a duplication of the central core motif of the cysteine-string domain of CSPα and affects palmitoylation-dependent CSPα sorting in cultured neuronal cells similarly to two previously described CSPα variants, p.(Leu115Arg) and p.(Leu116del). Interestingly, the duplication was not detected initially by standard Sanger sequencing due to a preferential PCR amplification of the shorter wild-type allele and allelic dropout of the mutated DNAJC5 allele. It was also missed by subsequent whole-exome sequencing (WES). Its identification was facilitated by reanalysis of original WES data and modification of the PCR and Sanger sequencing protocols. Independently occurring variants in the genomic sequence of DNAJC5 encoding the cysteine-string domain of CSPα suggest that this region may be more prone to DNA replication errors and that insertions or duplications within this domain should be considered in unsolved ANCL cases.
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http://dx.doi.org/10.1038/s41431-019-0567-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7253421PMC
June 2020

Duplication 2p16 is associated with perisylvian polymicrogyria.

Am J Med Genet A 2019 12 29;179(12):2343-2356. Epub 2019 Oct 29.

Department of Pediatrics (Genetics) and Neurology, University of Washington, and Seattle Children's Research Institute, Seattle, Washington.

Polymicrogyria (PMG) is a heterogeneous brain malformation that may result from prenatal vascular disruption or infection, or from numerous genetic causes that still remain difficult to identify. We identified three unrelated patients with polymicrogyria and duplications of chromosome 2p, defined the smallest region of overlap, and performed gene pathway analysis using Cytoscape. The smallest region of overlap in all three children involved 2p16.1-p16.3. All three children have bilateral perisylvian polymicrogyria (BPP), intrauterine and postnatal growth deficiency, similar dysmorphic features, and poor feeding. Two of the three children had documented intellectual disability. Gene pathway analysis suggested a number of developmentally relevant genes and gene clusters that were over-represented in the critical region. We narrowed a rare locus for polymicrogyria to a region of 2p16.1-p16.3 that contains 33-34 genes, 23 of which are expressed in cerebral cortex during human fetal development. Using pathway analysis, we showed that several of the duplicated genes contribute to neurodevelopmental pathways including morphogen, cytokine, hormonal and growth factor signaling, regulation of cell cycle progression, cell morphogenesis, axonal guidance, and neuronal migration. These findings strengthen the evidence for a novel locus associated with polymicrogyria on 2p16.1-p16.3, and comprise the first step in defining the underlying genetic etiology.
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http://dx.doi.org/10.1002/ajmg.a.61342DOI Listing
December 2019

Kufs disease due to mutation of CLN6: clinical, pathological and molecular genetic features.

Brain 2019 01;142(1):59-69

Department of Neurophysiology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.

Kufs disease is the major adult form of neuronal ceroid lipofuscinosis, but is rare and difficult to diagnose. Diagnosis was traditionally dependent on the demonstration of characteristic storage material, but distinction from normal age-related accumulation of lipofuscin can be challenging. Mutation of CLN6 has emerged as the most important cause of recessive Kufs disease but, remarkably, is also responsible for variant late infantile ceroid lipofuscinosis. Here we provide a detailed description of Kufs disease due to CLN6 pathogenic variants. We studied 20 cases of Kufs disease with CLN6 pathogenic variants from 13 unrelated families. Mean age of onset was 28 years (range 12-51) with bimodal peaks in teenage and early adult life. The typical presentation was of progressive myoclonus epilepsy with debilitating myoclonic seizures and relatively infrequent tonic-clonic seizures. Patients became wheelchair-bound with a mean 12 years post-onset. Ataxia was the most prominent motor feature. Dementia appeared to be an invariable accompaniment, although it could take a number of years to manifest and occasionally cognitive impairment preceded myoclonic seizures. Patients were usually highly photosensitive on EEG. MRI showed progressive cerebral and cerebellar atrophy. The median survival time was 26 years from disease onset. Ultrastructural examination of the pathology revealed fingerprint profiles as the characteristic inclusions, but they were not reliably seen in tissues other than brain. Curvilinear profiles, which are seen in the late infantile form, were not a feature. Of the 13 unrelated families we observed homozygous CLN6 pathogenic variants in four and compound heterozygous variants in nine. Compared to the variant late infantile form, there was a lower proportion of variants that predicted protein truncation. Certain heterozygous missense variants in the same amino acid position were found in both variant late infantile and Kufs disease. There was a predominance of cases from Italy and surrounding regions; this was partially explained by the discovery of three founder pathogenic variants. Clinical distinction of type A (progressive myoclonus epilepsy) and type B (dementia with motor disturbance) Kufs disease was supported by molecular diagnoses. Type A is usually caused by recessive pathogenic variants in CLN6 or dominant variants in DNAJC5. Type B Kufs is usually associated with recessive CTSF pathogenic variants. The diagnosis of Kufs remains challenging but, with the availability of genetic diagnosis, this will largely supersede the use of diagnostic biopsies, particularly as biopsies of peripheral tissues has unsatisfactory sensitivity and specificity.
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http://dx.doi.org/10.1093/brain/awy297DOI Listing
January 2019

Sodium Channel SCN3A (Na1.3) Regulation of Human Cerebral Cortical Folding and Oral Motor Development.

Neuron 2018 09 23;99(5):905-913.e7. Epub 2018 Aug 23.

Department of Pathology, Boston Children's Hospital, Boston, MA 02115, USA. Electronic address:

Channelopathies are disorders caused by abnormal ion channel function in differentiated excitable tissues. We discovered a unique neurodevelopmental channelopathy resulting from pathogenic variants in SCN3A, a gene encoding the voltage-gated sodium channel Na1.3. Pathogenic Na1.3 channels showed altered biophysical properties including increased persistent current. Remarkably, affected individuals showed disrupted folding (polymicrogyria) of the perisylvian cortex of the brain but did not typically exhibit epilepsy; they presented with prominent speech and oral motor dysfunction, implicating SCN3A in prenatal development of human cortical language areas. The development of this disorder parallels SCN3A expression, which we observed to be highest early in fetal cortical development in progenitor cells of the outer subventricular zone and cortical plate neurons and decreased postnatally, when SCN1A (Na1.1) expression increased. Disrupted cerebral cortical folding and neuronal migration were recapitulated in ferrets expressing the mutant channel, underscoring the unexpected role of SCN3A in progenitor cells and migrating neurons.
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http://dx.doi.org/10.1016/j.neuron.2018.07.052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6226006PMC
September 2018

Evidence of linkage to chromosome 5p13.2-q11.1 in a large inbred family with genetic generalized epilepsy.

Epilepsia 2018 08 4;59(8):e125-e129. Epub 2018 Jul 4.

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

The clinical genetics of genetic generalized epilepsy suggests complex inheritance; large pedigrees, with multiple affected individuals, are rare exceptions. We studied a large consanguineous family from Turkey where extensive electroclinical phenotyping revealed a familial phenotype most closely resembling juvenile myoclonic epilepsy. For a subject to be considered affected (n = 14), a diagnostic electroencephalogram was required. Seizure onset ranged between 6 and 19 years (mean = 12 years). Thirteen of 14 experienced myoclonic jerks; in 11, this was associated with eyelid blinking, and in 10 it was interspersed with absences. Generalized tonic-clonic seizures were seen in 11. One individual had generalized tonic-clonic seizures alone. Electroencephalograms demonstrated generalized polyspike and wave discharges that were not associated with photoparoxysmal response. Intellect was normal. Nineteen family members were subsequently chosen for nonparametric multipoint linkage analyses, which identified a 39.5 Mb region on chromosome 5 (P < 0.0001). Iterative analysis, including discovery of a subtly affected individual, narrowed the critical region to 15.4 Mb and possibly to 5.5 Mb. Homozygous versus heterozygous state of the refined 5p13.2-q11.1 haplotype was not associated with phenotypic severity or onset age, suggesting that one versus two pathogenic variants may result in similar phenotypes. Whole exome sequencing (n = 3) failed to detect any rare, protein-coding variants within the highly significant linkage region that includes HCN1 as a promising candidate.
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http://dx.doi.org/10.1111/epi.14506DOI Listing
August 2018

Psychiatric and cognitive adverse events: A pooled analysis of three phase III trials of adjunctive eslicarbazepine acetate for partial-onset seizures.

Epilepsy Behav 2018 05 28;82:119-127. Epub 2018 Mar 28.

Sunovion Pharmaceuticals Inc., 84 Waterford Dr, Marlborough, MA 01752, USA.

Objective: To evaluate the nature and incidence of psychiatric and cognitive adverse events (AEs) reported with eslicarbazepine acetate (ESL) used as adjunctive treatment for refractory partial-onset seizures (POS) in adults.

Methods: This was a post-hoc analysis of data pooled from three randomized double-blind, placebo-controlled trials (BIA-2093-301, -302, -304). After an 8-week baseline period, patients received placebo or adjunctive ESL 400mg (studies 301 and 302 only), 800mg, or 1200mg once daily (QD) for 14weeks (2-week titration period, 12-week maintenance period). Psychiatric and cognitive AEs were identified from individual patient data. Suicidality was also evaluated using the Columbia-Classification Algorithm of Suicide Assessment (C-CASA), or the Columbia-Suicide Severity Rating Scale (C-SSRS). P-values were obtained using the chi-square test of independence or Fisher's exact test, without correcting for multiplicity.

Results: The analysis population included 1447 patients (ESL, n=1021; placebo, n = 426). Psychiatric treatment-emergent AEs (TEAEs) occurred in 10.8% of patients receiving ESL, and in a comparable proportion (10.3%) of patients receiving placebo (p=0.802). The incidence of depression and suicidality-related TEAEs was higher for ESL (7.4%) vs. placebo (3.8%) (p=0.009). The occurrence of these TEAEs differed between treatment groups (p = 0.010), but there was no notable trend between increasing ESL dose and increasing incidence of depression and suicidality-related TEAEs. Aggression/hostility-related TEAEs occurred in <0.1% of patients taking ESL vs. 0.9% taking placebo. The incidence of cognitive TEAEs was higher for ESL (7.1%) vs. placebo (4.0%) (p=0.023); incidences of memory impairment, attention disturbance, apathy, and aphasia were higher for ESL 1200mg than for other treatment groups. Incidences of psychiatric and cognitive serious AEs (SAEs) were 0.6% and 0.2% with ESL, and 0.5% and 0% with placebo, respectively. Psychiatric and cognitive TEAEs leading to discontinuation occurred in 1.9% and 1.4% of patients taking ESL, and 0.7% and 0.5% taking placebo, respectively.

Conclusions: In phase III clinical trials of adjunctive ESL for treatment-refractory POS, psychiatric and cognitive TEAEs were reported infrequently with ESL and placebo. The incidences of depression and suicidality-related TEAEs and of cognitive TEAEs were higher for patients taking ESL vs. placebo. Incidences of psychiatric and cognitive SAEs, and TEAEs leading to discontinuation, were low with ESL and placebo.
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http://dx.doi.org/10.1016/j.yebeh.2017.12.017DOI Listing
May 2018

Myoclonus epilepsy and ataxia due to KCNC1 mutation: Analysis of 20 cases and K channel properties.

Ann Neurol 2017 May;81(5):677-689

Department of Neurology and Epileptology, Epilepsy Center Hamburg-Alsterdorf, Hamburg, Germany.

Objective: To comprehensively describe the new syndrome of myoclonus epilepsy and ataxia due to potassium channel mutation (MEAK), including cellular electrophysiological characterization of observed clinical improvement with fever.

Methods: We analyzed clinical, electroclinical, and neuroimaging data for 20 patients with MEAK due to recurrent KCNC1 p.R320H mutation. In vitro electrophysiological studies were conducted using whole cell patch-clamp to explore biophysical properties of wild-type and mutant K 3.1 channels.

Results: Symptoms began at between 3 and 15 years of age (median = 9.5), with progressively severe myoclonus and rare tonic-clonic seizures. Ataxia was present early, but quickly became overshadowed by myoclonus; 10 patients were wheelchair-bound by their late teenage years. Mild cognitive decline occurred in half. Early death was not observed. Electroencephalogram (EEG) showed generalized spike and polyspike wave discharges, with documented photosensitivity in most. Polygraphic EEG-electromyographic studies demonstrated a cortical origin for myoclonus and striking coactivation of agonist and antagonist muscles. Magnetic resonance imaging revealed symmetrical cerebellar atrophy, which appeared progressive, and a prominent corpus callosum. Unexpectedly, transient clinical improvement with fever was noted in 6 patients. To explore this, we performed high-temperature in vitro recordings. At elevated temperatures, there was a robust leftward shift in activation of wild-type K 3.1, increasing channel availability.

Interpretation: MEAK has a relatively homogeneous presentation, resembling Unverricht-Lundborg disease, despite the genetic and biological basis being quite different. A remarkable improvement with fever may be explained by the temperature-dependent leftward shift in activation of wild-type K 3.1 subunit-containing channels, which would counter the loss of function observed for mutant channels, highlighting KCNC1 as a potential target for precision therapeutics. Ann Neurol 2017;81:677-689.
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http://dx.doi.org/10.1002/ana.24929DOI Listing
May 2017

Research conference summary from the 2014 International Task Force on -Related Disorders.

Neurol Genet 2017 Apr 2;3(2):e139. Epub 2017 Mar 2.

Department of Pediatrics and Pediatric Neurology (H.R.), Georg August University, Göttingen, Germany; Division of Clinical Genetics (L.V.), Department of Pediatrics (T.N., M.T.S.) and Department of Neurology (M.T.S.), University of Utah, Salt Lake City; Center for Human Genetics (S.D.), University Hospitals and Case Western Reserve University, Cleveland, OH; Division of Pediatric Neurology (K.E.), Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN; Center for Human Genetics Research (L.O., M.M., K. Swoboda), Department of Neurology, Massachusetts General Hospital, Boston; Neurogenetics Unit (E.A.) and Epilepsy Research Group (E.A., F.A.), Montreal Neurological Hospital and Institute; Department of Neurology and Neurosurgery (E.A., F.A.), Department of Human Genetics (E.A.), and Department of Pediatrics (F.A.), McGill University, Quebec, Canada; Alternating Hemiplegia of Childhood Foundation (G.A., S.C., L.E., V.P.), Southfield, MI; BCBA (A. Belgrade), Belgrade Behavior Consulting, Chicago, IL; Department of Neurology (A. Brashear), Wake Forest School of Medicine, Winston-Salem, NC; Department of Pharmacology (A.L.G.), Northwestern University Feinberg School of Medicine, Chicago, IL; Department of Pediatrics (A.L.), University of Florida College of Medicine, Jacksonville; Integrative Neuropsychology (J.M.), Fairlawn, OH; Association Française de l'Hémiplégie Alternante (D.P.), Paris, France; Rare Disease Innovation Unit (S.R.), Clinical Development Program, Biogen, Cambridge, MA; Department of Child Neurology (M.S.), National Center of Neurology and Psychiatry, Kodaira, Japan; Swedish Neuroscience Institute (M.S.d.M.), Swedish Medical Center, Seattle, WA; Department of Neurosurgery (K. Sweadner), Massachusetts General Hospital and Harvard Medical School, Boston; Neuroscience Institute (M.Z.), Children's Hospital of Orange County, CA; and Departments of Pediatrics and Neurology (K. Silver), University of Chicago and Comer Children's Hospital, Chicago, IL.

Objective: -related neurologic disorders encompass a broad range of phenotypes that extend well beyond initial phenotypic criteria associated with alternating hemiplegia of childhood (AHC) and rapid-onset dystonia parkinsonism.

Methods: In 2014, the Alternating Hemiplegia of Childhood Foundation hosted a multidisciplinary workshop intended to address fundamental challenges surrounding the diagnosis and management of individuals with -related disorders.

Results: Workshop attendees were charged with the following: (1) to achieve consensus on expanded diagnostic criteria to facilitate the identification of additional patients, intended to supplement existing syndrome-specific diagnostic paradigms; (2) to standardize definitions for the broad range of paroxysmal manifestations associated with AHC to disseminate to families; (3) to create clinical recommendations for common recurrent issues facing families and medical care providers; (4) to review data related to the death of individuals in the Alternating Hemiplegia of Childhood Foundation database to guide future efforts in identifying at-risk subjects and potential preventative measures; and (5) to identify critical gaps where we most need to focus national and international research efforts.

Conclusions: This report summarizes recommendations of the workshop committee, highlighting the key phenotypic features to facilitate the diagnosis of possible mutations, providing recommendations for genetic testing, and outlining initial acute management for common recurrent clinical conditions, including epilepsy.
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http://dx.doi.org/10.1212/NXG.0000000000000139DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5335249PMC
April 2017

Myoclonus and seizures in progressive myoclonus epilepsies: pharmacology and therapeutic trials.

Epileptic Disord 2016 Sep;18(S2):145-153

Centre Saint-Paul - Hôpital Henri-Gastaut, Marseille, France.

Generalized motor seizures, usually tonic-clonic, tonic-vibratory, myoclonic or clonic, and stimulus-sensitive/action myoclonus are typical features of progressive myoclonus epilepsies (PMEs). Despite the introduction of many anticonvulsants, the treatment of these symptoms, particularly myoclonus, remains challenging, due to the incomplete and often transitory effects of most drugs. Moreover, treatment is only symptomatic, since therapy targeting the underlying aetiology for these genetic conditions is in its infancy. Traditional antiepileptic drugs for the treatment of PMEs are valproate, clonazepam, and phenobarbital (or primidone). These drugs may improve the overall performance of PME patients by decreasing their generalized seizures and, to a lesser extent, their myoclonic jerks. Newer drugs which have been shown to be effective include piracetam, levetiracetam, topiramate, zonisamide, and possibly perampanel for Lafora disease. The potential of other drugs (such as L-triptophan and N-acetylcysteine) and procedures (such as vagal and deep brain stimulation) has also been discussed. The available data on the efficacy of drugs are mainly based on small series or anecdotal reports. Two prospective, randomized, double blind studies investigating the novel SV2A ligand, brivaracetam, in genetically confirmed Unverricht-Lundborg patients have been performed with disappointing results. When treating PMEs, particular care should be paid to avoid drugs known to aggravate myoclonus or myoclonic seizures, such as phenytoin, carbamazepine, oxcarbazepine, lamotrigine, vigabatrin, tiagabine, gabapentin, and pregabalin. The emergency treatment of motor status, which often complicates the course of PMEs, consists of intravenous administration of benzodiazepines, valproate, or levetiracetam.
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http://dx.doi.org/10.1684/epd.2016.0861DOI Listing
September 2016

Brivaracetam in Unverricht-Lundborg disease (EPM1): Results from two randomized, double-blind, placebo-controlled studies.

Epilepsia 2016 Feb 15;57(2):210-21. Epub 2015 Dec 15.

UCB Pharma, Smyrna, Georgia, U.S.A.

Objective: To evaluate efficacy, tolerability, and safety of adjunctive brivaracetam (BRV) in patients with Unverricht-Lundborg disease (EPM1).

Methods: Two prospective, multicenter, double-blind, phase III trials (N01187/NCT00357669; N01236/NCT00368251) in patients (≥16 years) with genetically ascertained EPM1, showing moderate-severe myoclonus (action myoclonus score ≥30/160), randomized (1:1:1) to twice-daily BRV (N01187: 50 or 150 mg/day; N01236: 5 or 150 mg/day), or placebo. Both studies comprised a baseline period (2 weeks), 2-week up-titration period, 12-week stable-dose maintenance period, and down-titration or entry into long-term follow-up study. Symptoms of myoclonus were assessed by Unified Myoclonus Rating Scale (UMRS). Primary efficacy end point was percent reduction from baseline in action myoclonus score (UMRS section 4) at last treatment visit. Safety assessments included treatment-emergent adverse events (TEAEs).

Results: N01187: 50 patients randomized, 47 completed; N01236: 56 patients randomized, 54 completed. Median (min-max) percent reduction from baseline in action myoclonus score is the following-N01187: placebo 5.6 (-81.3 to 53.8), pooled BRV group (primary efficacy analysis) 21.4 (-50.0 to 73.6), BRV 50 mg/day 26.3 (-35.8 to 69.2), BRV 150 mg/day 16.9 (-50.0 to 73.6); N01236: placebo 17.5 (-170 to 61.5), BRV 5 mg/day -4.6 (-430 to 81.8), BRV 150 mg/day (primary efficacy analysis) 12.3 (-58.3 to 96.9). Estimated differences versus placebo were not statistically significant. TEAEs were reported by 72-75% placebo-treated and 56-83% BRV-treated patients.

Significance: Effect of BRV on action myoclonus was not statistically significant. However, action myoclonus score showed wide intrapatient variability and may not have been the optimal tool to measure severity of myoclonus in EPM1. Both studies had very high completion rates (95.3% overall), and a high percentage of patients (88.7% overall) entered long-term follow-up; both likely to be influenced by good tolerability. These studies demonstrate the feasibility of rigorous trials in progressive myoclonic epilepsy.
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http://dx.doi.org/10.1111/epi.13275DOI Listing
February 2016

The histopathology of polymicrogyria: a series of 71 brain autopsy studies.

Dev Med Child Neurol 2016 Jan 14;58(1):39-48. Epub 2015 Jul 14.

Department of Neuropathology, Oxford University John Radcliffe Hospital, Oxford, UK.

Aim: Polymicrogyria (PMG) is one of the most common forms of cortical malformation yet the mechanism of its development remains unknown. This study describes the histopathological aspects of PMG in a large series including a significant proportion of fetal cases.

Method: We have reviewed the neuropathology and medical records of 44 fetuses and 27 children and adults in whom the cortical architecture was focally or diffusely replaced by one or more festooning bands of neurons.

Results: The pial surface of the brain overlying the polymicrogyric cortex was abnormal in almost 90% of cases irrespective of the aetiology. This accords with animal studies indicating the importance of the leptomeninges in cortical development. The aetiology of PMG was highly heterogeneous and there was no correlation between cortical layering patterns and aetiology. PMG was almost always associated with other brain malformations.

Interpretation: The inclusion of many fetal cases has allowed us to examine the early developmental stages of PMG. The study indicates the significance of surface signals responsible for human corticogenesis and the complex interaction between genetic and environmental factors leading to this common endpoint of cortical maldevelopment.
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http://dx.doi.org/10.1111/dmcn.12840DOI Listing
January 2016

Alternating Hemiplegia of Childhood: Retrospective Genetic Study and Genotype-Phenotype Correlations in 187 Subjects from the US AHCF Registry.

PLoS One 2015 21;10(5):e0127045. Epub 2015 May 21.

Institute for Systems Biology, Seattle, Washington, United States of America.

Mutations in ATP1A3 cause Alternating Hemiplegia of Childhood (AHC) by disrupting function of the neuronal Na+/K+ ATPase. Published studies to date indicate 2 recurrent mutations, D801N and E815K, and a more severe phenotype in the E815K cohort. We performed mutation analysis and retrospective genotype-phenotype correlations in all eligible patients with AHC enrolled in the US AHC Foundation registry from 1997-2012. Clinical data were abstracted from standardized caregivers' questionnaires and medical records and confirmed by expert clinicians. We identified ATP1A3 mutations by Sanger and whole genome sequencing, and compared phenotypes within and between 4 groups of subjects, those with D801N, E815K, other ATP1A3 or no ATP1A3 mutations. We identified heterozygous ATP1A3 mutations in 154 of 187 (82%) AHC patients. Of 34 unique mutations, 31 (91%) are missense, and 16 (47%) had not been previously reported. Concordant with prior studies, more than 2/3 of all mutations are clusteredin exons 17 and 18. Of 143 simplex occurrences, 58 had D801N (40%), 38 had E815K(26%) and 11 had G947R (8%) mutations [corrected].Patients with an E815K mutation demonstrate an earlier age of onset, more severe motor impairment and a higher prevalence of status epilepticus. This study further expands the number and spectrum of ATP1A3 mutations associated with AHC and confirms a more deleterious effect of the E815K mutation on selected neurologic outcomes. However, the complexity of the disorder and the extensive phenotypic variability among subgroups merits caution and emphasizes the need for further studies.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0127045PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4440742PMC
February 2016

Familial focal epilepsy with focal cortical dysplasia due to DEPDC5 mutations.

Ann Neurol 2015 Apr 13;77(4):675-83. Epub 2015 Mar 13.

Sorbonne Universités, Pierre and Marie Curie University, UPMC Univ Paris 06, UM 75, ICM, Paris, France; National Institute of Health and Medical Research, INSERM U1127, ICM, Paris, France; National Center for Scientific Research, CNRS, UMR 7225, ICM, Paris, France; Brain and Spine Institute, Institut du Cerveau et de la Moelle (ICM), Paris, France.

Objective: The DEPDC5 (DEP domain-containing protein 5) gene, encoding a repressor of the mTORC1 signaling pathway, has recently emerged as a major gene mutated in familial focal epilepsies. We aimed to further extend the role of DEPDC5 to focal cortical dysplasias (FCDs).

Methods: Seven patients from 4 families with DEPDC5 mutations and focal epilepsy associated with FCD were recruited and investigated at the clinical, neuroimaging, and histopathological levels. The DEPDC5 gene was sequenced from genomic blood and brain DNA.

Results: All patients had drug-resistant focal epilepsy, 5 of them underwent surgery, and 1 had a brain biopsy. Electroclinical phenotypes were compatible with FCD II, although magnetic resonance imaging (MRI) was typical in only 4 cases. Histopathology confirmed FCD IIa in 2 patients (including 1 MRI-negative case) and showed FCD I in 2 other patients, and remained inconclusive in the last 2 patients. Three patients were seizure-free postsurgically, and 1 had a worthwhile improvement. Sequencing of blood DNA revealed truncating DEPDC5 mutations in all 4 families; 1 mutation was found to be mosaic in an asymptomatic father. A brain somatic DEPDC5 mutation was identified in 1 patient in addition to the germline mutation.

Interpretation: Germline, germline mosaic, and brain somatic DEPDC5 mutations may cause epilepsy associated with FCD, reinforcing the link between mTORC1 pathway and FCDs. Similarly to other mTORopathies, a "2-hit" mutational model could be responsible for cortical lesions. Our study also indicates that epilepsy surgery is a valuable alternative in the treatment of drug-resistant DEPDC5-positive focal epilepsies, even if the MRI is unremarkable.
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http://dx.doi.org/10.1002/ana.24368DOI Listing
April 2015

A recurrent de novo mutation in KCNC1 causes progressive myoclonus epilepsy.

Nat Genet 2015 Jan 17;47(1):39-46. Epub 2014 Nov 17.

Department of Neurology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey.

Progressive myoclonus epilepsies (PMEs) are a group of rare, inherited disorders manifesting with action myoclonus, tonic-clonic seizures and ataxia. We sequenced the exomes of 84 unrelated individuals with PME of unknown cause and molecularly solved 26 cases (31%). Remarkably, a recurrent de novo mutation, c.959G>A (p.Arg320His), in KCNC1 was identified as a new major cause for PME. Eleven unrelated exome-sequenced (13%) and two affected individuals in a secondary cohort (7%) had this mutation. KCNC1 encodes KV3.1, a subunit of the KV3 voltage-gated potassium ion channels, which are major determinants of high-frequency neuronal firing. Functional analysis of the Arg320His mutant channel showed a dominant-negative loss-of-function effect. Ten cases had pathogenic mutations in known PME-associated genes (NEU1, NHLRC1, AFG3L2, EPM2A, CLN6 and SERPINI1). Identification of mutations in PRNP, SACS and TBC1D24 expand their phenotypic spectra to PME. These findings provide insights into the molecular genetic basis of PME and show the role of de novo mutations in this disease entity.
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http://dx.doi.org/10.1038/ng.3144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4281260PMC
January 2015

Rasmussen encephalitis and comorbid autoimmune diseases: A window into disease mechanism?

Neurology 2014 Sep 20;83(12):1049-55. Epub 2014 Aug 20.

From the Neurogenetics Unit (D.A., E.A.), Epilepsy Clinic (F.A.), and Neuroimmunology Unit (A.B.-O.), Montreal Neurological Hospital and Institute, Quebec, Canada; Departments of Neurology & Neurosurgery (D.A., F.A., E.A., A.B.-O.), Pediatrics (F.A.), and Human Genetics (E.A.), McGill University, Montreal, Quebec, Canada; Okmeydani Education and Research Hospital (D.K.), Istanbul, Turkey; Royal Victoria Infirmary (Y.H.), Newcastle-upon-Tyne, UK; Epilepsy Research Center (S.F.B.), Department of Medicine (Neurology), University of Melbourne, Australia; and Department of Neurology (K.L.), University of California at San Francisco.

Objective: To describe a potential association between comorbid autoimmune disease and Rasmussen encephalitis (RE) and discuss potential insights into underlying RE pathogenesis.

Methods: We report a case series of 4 patients with RE in whom a comorbid autoimmune disease was subsequently diagnosed and review the literature on possible common susceptibility factors.

Results: In 4 patients who presented with typical clinical features of RE, a comorbid autoimmune disease was subsequently diagnosed: Hashimoto thyroiditis, ulcerative colitis, Crohn disease, and systemic lupus erythematosus. We discuss the possible common predisposing factors.

Conclusions: The association of RE, a rare entity, with a comorbid autoimmune disease raises the possibility of shared mechanisms of susceptibility, including common immunogenetic and/or environmental risk factors.
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http://dx.doi.org/10.1212/WNL.0000000000000791DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4166360PMC
September 2014

Somatic mutations in cerebral cortical malformations.

N Engl J Med 2014 Aug;371(8):733-43

From the Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Howard Hughes Medical Institute (S.S.J., A.-T.N.L., A.M.D., B.J.B., X.Z., R.S.H., J.N.P., A.R., S.S., B.K.M., T.W.Y., C.A.W.), and the Departments of Laboratory Medicine (J.W., Y.S., B.L.W.) and Neurology (M.S., A.P.), Boston Children's Hospital, the Departments of Pediatrics (S.S.J., A.-T.N.L., A.M.D., B.J.B., X.Z., R.S.H., J.N.P., A.R., S.S., B.K.M., T.W.Y., C.A.W.), Neurology (S.S.J., A.-T.N.L., A.M.D., B.J.B., X.Z., R.S.H., J.N.P., A.R., S.S., B.K.M., T.W.Y., C.A.W., M.S., A.P.), and Pathology (Y.S., B.L.W.), Harvard Medical School, the Department of Neurology, Beth Israel Deaconess Medical Center (B.S.C.), and the Department of Neurology, Massachusetts General Hospital (T.W.Y.) - all in Boston; the Department of Paediatrics, KK Women's and Children's Hospital, Singapore, Singapore (S.S.J.); the Department of Genome Sciences, University of Washington, Seattle (M.K., M.B., D.A.N., J.S.); the Department of Laboratory Medicine, Shanghai Children's Medical Center, Shanghai (J.W., Y.S.); the Division of Neurology, Department of Pediatrics, Hacettepe University School of Medicine, Sihhiye, Ankara, Turkey (M.T.); the Neurogenetics Unit, Montreal Neurological Hospital and Institute, Department of Neurology and Neurosurgery (D.A., E.A.) and Department of Human Genetics (E.A.), McGill University, Montreal; the Department of Neurology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels (B.D.); the Pediatric Neurology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy (E.P., R.G.); the Department of Medicine, University of Melbourne, Austin Health, Heidelberg (I.E.S., S.F.B.), Department of Paediatrics, Royal Children's Hospital, University of Melbourne, and the Florey Institute of Neuroscience and Mental Health, Melbourne (I.E.S.), and the Department of Neurology, Royal Children's Hospital, Murdoch Children'

Background: Although there is increasing recognition of the role of somatic mutations in genetic disorders, the prevalence of somatic mutations in neurodevelopmental disease and the optimal techniques to detect somatic mosaicism have not been systematically evaluated.

Methods: Using a customized panel of known and candidate genes associated with brain malformations, we applied targeted high-coverage sequencing (depth, ≥200×) to leukocyte-derived DNA samples from 158 persons with brain malformations, including the double-cortex syndrome (subcortical band heterotopia, 30 persons), polymicrogyria with megalencephaly (20), periventricular nodular heterotopia (61), and pachygyria (47). We validated candidate mutations with the use of Sanger sequencing and, for variants present at unequal read depths, subcloning followed by colony sequencing.

Results: Validated, causal mutations were found in 27 persons (17%; range, 10 to 30% for each phenotype). Mutations were somatic in 8 of the 27 (30%), predominantly in persons with the double-cortex syndrome (in whom we found mutations in DCX and LIS1), persons with periventricular nodular heterotopia (FLNA), and persons with pachygyria (TUBB2B). Of the somatic mutations we detected, 5 (63%) were undetectable with the use of traditional Sanger sequencing but were validated through subcloning and subsequent sequencing of the subcloned DNA. We found potentially causal mutations in the candidate genes DYNC1H1, KIF5C, and other kinesin genes in persons with pachygyria.

Conclusions: Targeted sequencing was found to be useful for detecting somatic mutations in patients with brain malformations. High-coverage sequencing panels provide an important complement to whole-exome and whole-genome sequencing in the evaluation of somatic mutations in neuropsychiatric disease. (Funded by the National Institute of Neurological Disorders and Stroke and others.).
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http://dx.doi.org/10.1056/NEJMoa1314432DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4274952PMC
August 2014

A new locus for familial temporal lobe epilepsy on chromosome 3q.

Epilepsy Res 2013 Oct 14;106(3):338-44. Epub 2013 Aug 14.

Department of Neurology, ULB-Hôpital Erasme, Brussels, Belgium.

Background: Temporal lobe epilepsy (TLE) is a common and heterogeneous focal epilepsy syndrome with a complex etiology, involving both environmental and genetic factors. Several familial forms of TLE have been described, including familial lateral TLE (FLTLE), familial mesial TLE (FMTLE) without hippocampal sclerosis, and FMTLE with hippocampal sclerosis. Mutations have been identified only in the leucine-rich, glioma-inactivated 1 (LGI1) gene on chromosome 10q22-q24 in FLTLE. Several loci have been mapped in families with FMTLE, but responsible genes have not been found. We report clinical evaluation in a large family with FMTLE and a new genetic locus.

Methods: We conducted a genome-wide scan using 10cM-spaced microsatellite markers on a family with TLE. Seven individuals had TLE without antecedent FS; four other individuals had FS during childhood, but no subsequent epilepsy. Patients with TLE had infrequent simple partial, complex partial and secondarily generalized seizures that generally responded well to treatment. The proband had no hippocampal sclerosis. The mode of inheritance appeared to be autosomal dominant with incomplete penetrance. Linkage analysis was performed using the Genehunter software. Regions with LOD score>1 and those that were poorly informative in the first-pass scan were further genotyped.

Results: Linkage was identified on chromosome 3q25-q26 in a 13cM region flanked by markers D3S1584 and D3S3520, with a peak LOD score of 3.23. This interval does not correspond to any previously known locus for familial epilepsy or FS. KCNAB1, encoding a voltage-gated, shaker-related potassium channel, and NLGN1, encoding a member of a family of neuronal cell surface protein were excluded as disease causing mutations.

Conclusion: We identified a novel locus for familial TLE with FS, providing additional evidence of the complexity and genetic heterogeneity of familial focal epilepsy.
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http://dx.doi.org/10.1016/j.eplepsyres.2013.07.007DOI Listing
October 2013

Role of the sodium channel SCN9A in genetic epilepsy with febrile seizures plus and Dravet syndrome.

Epilepsia 2013 Sep 29;54(9):e122-6. Epub 2013 Jul 29.

Department of Genetic Medicine, Directorate of Genetics and Molecular Pathology, SA Pathology at Women's and Children's Hospital, Adelaide, South Australia, Australia.

Mutations of the SCN1A subunit of the sodium channel is a cause of genetic epilepsy with febrile seizures plus (GEFS(+) ) in multiplex families and accounts for 70-80% of Dravet syndrome (DS). DS cases without SCN1A mutation inherited have predicted SCN9A susceptibility variants, which may contribute to complex inheritance for these unexplained cases of DS. Compared with controls, DS cases were significantly enriched for rare SCN9A genetic variants. None of the multiplex febrile seizure or GEFS(+) families could be explained by highly penetrant SCN9A mutations.
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http://dx.doi.org/10.1111/epi.12323DOI Listing
September 2013

SCN1A testing for epilepsy: application in clinical practice.

Epilepsia 2013 May 15;54(5):946-52. Epub 2013 Apr 15.

Department of Pediatrics and Research Institute for the Molecular Pathomechanisms of Epilepsy, Fukuoka University, Fukuoka, Japan.

This report is a practical reference guide for genetic testing of SCN1A, the gene encoding the α1 subunit of neuronal voltage-gated sodium channels (protein name: Nav 1.1). Mutations in this gene are frequently found in Dravet syndrome (DS), and are sometimes found in genetic epilepsy with febrile seizures plus (GEFS+), migrating partial seizures of infancy (MPSI), other infantile epileptic encephalopathies, and rarely in infantile spasms. Recommendations for testing: (1) Testing is particularly useful for people with suspected DS and sometimes in other early onset infantile epileptic encephalopathies such as MPSI because genetic confirmation of the clinical diagnosis may allow optimization of antiepileptic therapy with the potential to improve seizure control and developmental outcome. In addition, a molecular diagnosis may prevent the need for unnecessary investigations, as well as inform genetic counseling. (2) SCN1A testing should be considered in people with possible DS where the typical initial presentation is of a developmentally normal infant presenting with recurrent, febrile or afebrile prolonged, hemiclonic seizures or generalized status epilepticus. After age 2, the clinical diagnosis of DS becomes more obvious, with the classical evolution of other seizure types and developmental slowing. (3) In contrast to DS, the clinical utility of SCN1A testing for GEFS+ remains questionable. (4) The test is not recommended for children with phenotypes that are not clearly associated with SCN1A mutations such as those characterized by abnormal development or neurologic deficits apparent at birth or structural abnormalities of the brain. Interpreting test results: (1) Mutational testing of SCN1A involves both conventional DNA sequencing of the coding regions and analyses to detect genomic rearrangements within the relevant chromosomal region: 2q24. Interpretation of the test results must always be done in the context of the electroclinical syndrome and often requires the assistance of a medical geneticist, since many genomic variations are possible and it is essential to differentiate benign polymorphisms from pathogenic mutations. (2) Missense variants may have no apparent effect on the phenotype (benign polymorphisms) or may represent mutations underlying DS, MPSI, GEFS+, and related syndromes and can provide a challenge in interpretation. (3) Conventional methods do not detect variations in introns or promoter or regulatory regions; therefore, a negative test does not exclude a pathogenic role of SCN1A in a specific phenotype. (4) It is important to note that a negative test does not rule out the clinical diagnosis of DS or other conditions because genes other than SCN1A may be involved. Obtaining written informed consent and genetic counseling should be considered prior to molecular testing, depending on the clinical situation and local regulations.
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http://dx.doi.org/10.1111/epi.12168DOI Listing
May 2013

Mutations in DEPDC5 cause familial focal epilepsy with variable foci.

Nat Genet 2013 May 31;45(5):546-51. Epub 2013 Mar 31.

Epilepsy Research Program, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia.

The majority of epilepsies are focal in origin, with seizures emanating from one brain region. Although focal epilepsies often arise from structural brain lesions, many affected individuals have normal brain imaging. The etiology is unknown in the majority of individuals, although genetic factors are increasingly recognized. Autosomal dominant familial focal epilepsy with variable foci (FFEVF) is notable because family members have seizures originating from different cortical regions. Using exome sequencing, we detected DEPDC5 mutations in two affected families. We subsequently identified mutations in five of six additional published large families with FFEVF. Study of families with focal epilepsy that were too small for conventional clinical diagnosis with FFEVF identified DEPDC5 mutations in approximately 12% of families (10/82). This high frequency establishes DEPDC5 mutations as a common cause of familial focal epilepsies. Shared homology with G protein signaling molecules and localization in human neurons suggest a role of DEPDC5 in neuronal signal transduction.
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http://dx.doi.org/10.1038/ng.2599DOI Listing
May 2013

Cathepsin F mutations cause Type B Kufs disease, an adult-onset neuronal ceroid lipofuscinosis.

Hum Mol Genet 2013 Apr 7;22(7):1417-23. Epub 2013 Jan 7.

Bioinformatics Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia.

Kufs disease, an adult-onset neuronal ceroid lipofuscinosis, is challenging to diagnose and genetically heterogeneous. Mutations in CLN6 were recently identified in recessive Kufs disease presenting as progressive myoclonus epilepsy (Type A), whereas the molecular basis of cases presenting with dementia and motor features (Type B) is unknown. We performed genome-wide linkage mapping of two families with recessive Type B Kufs disease and identified a single region on chromosome 11 to which both families showed linkage. Exome sequencing of five samples from the two families identified homozygous and compound heterozygous missense mutations in CTSF within this linkage region. We subsequently sequenced CTSF in 22 unrelated individuals with suspected recessive Kufs disease, and identified an additional patient with compound heterozygous mutations. CTSF encodes cathepsin F, a lysosomal cysteine protease, dysfunction of which is a highly plausible candidate mechanism for a storage disorder like ceroid lipofuscinosis. In silico modeling suggested the missense mutations would alter protein structure and function. Moreover, re-examination of a previously published mouse knockout of Ctsf shows that it recapitulates the light and electron-microscopic pathological features of Kufs disease. Although CTSF mutations account for a minority of cases of type B Kufs, CTSF screening should be considered in cases with early-onset dementia and may avoid the need for invasive biopsies.
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http://dx.doi.org/10.1093/hmg/dds558DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3596852PMC
April 2013

Mutations in TMEM231 cause Joubert syndrome in French Canadians.

J Med Genet 2012 Oct 25;49(10):636-41. Epub 2012 Sep 25.

Centre of Excellence in Neurosciences of Université de Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada H3T 1C5.

Background: Joubert syndrome (JBTS) is a predominantly autosomal recessive disorder characterised by a distinctive midhindbrain malformation, oculomotor apraxia, breathing abnormalities and developmental delay. JBTS is genetically heterogeneous, involving genes required for formation and function of non-motile cilia. Here we investigate the genetic basis of JBTS in 12 French-Canadian (FC) individuals.

Methods And Results: Exome sequencing in all subjects showed that six of them carried rare compound heterozygous mutations in CC2D2A or C5ORF42, known JBTS genes. In addition, three individuals (two families) were compound heterozygous for the same rare mutations in TMEM231(c.12T>A[p.Tyr4*]; c.625G>A[p.Asp209Asn]). All three subjects showed a severe neurological phenotype and variable presence of polydactyly, retinopathy and renal cysts. These mutations were not detected among 385 FC controls. TMEM231 has been previously shown to localise to the ciliary transition zone, and to interact with several JBTS gene products in a complex involved in the formation of the diffusion barrier between the cilia and plasma membrane. siRNA knockdown of TMEM231 was also shown to affect barrier integrity, resulting in a reduction of cilia formation and ciliary localisation of signalling receptors.

Conclusions: Our data suggest that mutations in TMEM231 cause JBTS, reinforcing the relationship between this condition and the disruption of the barrier at the ciliary transition zone.
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http://dx.doi.org/10.1136/jmedgenet-2012-101132DOI Listing
October 2012

Peritrigonal and temporo-occipital heterotopia with corpus callosum and cerebellar dysgenesis.

Neurology 2012 Sep 22;79(12):1244-51. Epub 2012 Aug 22.

Pediatric Neurology and Neurogenetics Unit, Children’s Hospital A. Meyer-University of Florence, Florence, Italy.

Objective: To describe a homogeneous subtype of periventricular nodular heterotopia (PNH) as part of a newly defined malformation complex.

Methods: Observational study including review of brain MRI and clinical findings of a cohort of 50 patients with PNH in the temporo-occipital horns and trigones, mutation analysis of the FLNA gene, and anatomopathologic study of a fetal brain.

Results: There were 28 females and 22 males. All were sporadic with the exception of an affected mother and son. Epilepsy occurred in 62%, cerebellar signs in 56%, cognitive impairment in 56%, and autism in 12%. Seventy percent were referred within the 3rd year of life. Imaging revealed a normal cerebral cortex in 76% and abnormal cortical folding in 24%. In all patients the hippocampi were under-rotated and in 10% they merged with the heterotopia. Cerebellar dysgenesis was observed in 84% and a hypoplastic corpus callosum in 60%. There was no gender bias or uneven gender distribution of clinical and anatomic severity. No mutations of FLNA occurred in 33 individuals examined. Heterotopia in the fetal brain revealed cytoarchitectonic characteristics similar to those associated with FLNA mutations; cortical pathology was not typical of polymicrogyria. Cerebellar involvement was more severe and the hippocampi appeared simple and under-rotated.

Conclusions: This series delineates a malformation complex in which PNH in the trigones and occipito-temporal horns is associated with hippocampal, corpus callosum, and cerebellar dysgenesis. This subtype of PNH is distinct from classic PNH caused by FLNA mutations.
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http://dx.doi.org/10.1212/WNL.0b013e31826aac88DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3440449PMC
September 2012

Genotype-phenotype correlation in interstitial 6q deletions: a report of 12 new cases.

Neurogenetics 2012 Feb 5;13(1):31-47. Epub 2012 Jan 5.

Signature Genomic Laboratories, PerkinElmer, Inc., 2820 N. Astor St., Spokane, WA 99207, USA.

Interstitial deletions of 6q are associated with variable phenotypes, including growth retardation, dysmorphic features, upper limb malformations, and Prader-Willi (PW)-like features. Only a minority of cases in the literature have been characterized with high resolution techniques, making genotype-phenotype correlations difficult. We report 12 individuals with overlapping, 200-kb to 16.4-Mb interstitial deletions within 6q15q22.33 characterized by microarray-based comparative genomic hybridization to better correlate deletion regions with specific phenotypes. Four individuals have a PW-like phenotype, though only two have deletion of SIM1, the candidate gene for this feature. Therefore, other genes on 6q may contribute to this phenotype including multiple genes on 6q16 and our newly proposed candidate, the transcription cofactor gene VGLL2 on 6q22.2. Two individuals present with movement disorders as a major feature, and ataxia is present in a third. The 4.1-Mb 6q22.1q22.2 critical region for movement disorders includes the cerebellar-expressed candidate gene GOPC. Observed brain malformations include thick corpus callosum in two subjects, cerebellar vermal hypoplasia in two subjects, and cerebellar atrophy in one subject. Seven subjects' deletions overlap a ~250-kb cluster of four genes on 6q22.1 including MARCKS, HDAC2, and HS3ST5, which are involved in neural development. Two subjects have only this gene cluster deleted, and one deletion was apparently de novo, suggesting at least one of these genes plays an important role in development. Although the phenotypes associated with 6q deletions can vary, using overlapping deletions to delineate critical regions improves genotype-phenotype correlation for interstitial 6q deletions.
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http://dx.doi.org/10.1007/s10048-011-0306-5DOI Listing
February 2012
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