Biomedical subjects

Rima Nabbout

Publications and source records attributed to Rima Nabbout.

11 recordsLinked to original sources

PubMed2026

Genetic testing practices across European epilepsy centers: An ERN EpiCARE survey.

OBJECTIVE: Genetic testing plays an increasing role in the diagnostic pathway for rare and complex epilepsies. However, significant heterogeneity persists in access, implementation, and interpretation across Europe. This study aimed to assess genetic testing practices, accessibility, and challenges across expert epilepsy centers within the European Reference Network for Rare and Complex Epilepsies (ERN EpiCARE) and to identify key challenges and areas for harmonization. METHODS: A cross-sectional survey was developed by the ERN EpiCARE Clinical Genetics Working Group and distributed to 50 EpiCARE member centers across 27 European countries. The questionnaire collected quantitative and qualitative information on available genetic testing modalities, turnaround times, use of rapid testing, multidisciplinary team (MDT) organization, genetic counseling practices, and perceived challenges. Survey findings were complemented by a structured discussion held during the ERN EpiCARE General Assembly. RESULTS: Responses were received from 46 centers (51 responses). Most centers reported access to genetic testing, predominantly through in-house facilities. Whole-exome sequencing was available in 85% of centers, and gene panels were available in 78%. Whole-genome sequencing was available in 59% of centers, frequently restricted to research or performed externally. Turnaround times for standard genetic testing were most commonly between 1 and 6 months. Genetic testing strategies varied by epilepsy subtype, with gene panels most frequently used as first-tier testing, and exome sequencing preferentially applied in developmental and epileptic encephalopathies. Considerable heterogeneity was observed in MDT organization, access to genetic counseling, reimbursement, data-sharing and registry infrastructures. SIGNIFICANCE: Although genetic testing is widely available across ERN EpiCARE centers, substantial disparities persist in its organization, accessibility, and implementation. Addressing these gaps through strengthened multidisciplinary collaboration, harmonized diagnostic strategies, and enhanced European-level coordination will be essential to ensure equitable access to high-quality genetic care for individuals with epilepsy. PLAIN LANGUAGE SUMMARY: Genetic testing is increasingly integrated in the diagnostic pathway for rare and complex epilepsies and treatment decisions. An ERN EpiCARE survey assessed how genetic testing is implemented across specialist epilepsy centers in Europe and identified persistent organizational, financial, and clinical barriers. Although most centers had access to advanced genomic testing, important differences were identified in access, reimbursement, turnaround times, and multidisciplinary expertise. European collaboration and harmonized practices are needed to support equitable access to high-quality genetic care for people living with epilepsy.

European reference networks↗

PubMed2006

Evaluation of CACNA1H in European patients with childhood absence epilepsy.

CACNA1H was evaluated in a resource of Caucasian European patients with childhood absence epilepsy by linkage analysis and typing of sequence variants previously identified in Chinese patients. Linkage analysis of 44 pedigrees provided no evidence for a locus in the CACNA1H region and none of the Chinese variants were found in 220 unrelated patients.

Asian People↗

PubMed2006

Parental mosaicism can cause recurrent transmission of SCN1A mutations associated with severe myoclonic epilepsy of infancy.

De novo mutations in the SCN1A gene, encoding the alpha1-subunit of the neuronal voltage-gated sodium channel Nav1.1, are the most frequent genetic cause of Severe Myoclonic Epilepsy of Infancy known so far. A few mutations inherited from an asymptomatic or mildly affected parent have been reported, suggesting that expression of the mutated gene may be variable in the transmitting parent. In this study, we report two unrelated families in which two children of unaffected parents had deleterious SCN1A mutations, and show evidence of somatic and germline mosaicism in the transmitting parents. In one of these families, direct sequencing of blood cell DNA was not sufficient to the SCN1A mutation in the transmitting asymptomatic parent who was mosaic for the mutation. We therefore developed a real-time PCR assay to selectively amplify and quantify the mutant allele present at low levels in the transmitting parent in both families. The allele-specific PCR technique used in this study will be of use in detecting other such cases. These findings will have major consequences for the genetic counseling of asymptomatic parents with only one affected child.

Adult↗

PubMed2006

Epilepsy in Menkes disease: analysis of clinical stages.

PURPOSE: Epilepsy is one of the main features of Menkes disease (MD), although it is not described in depth. To determine the spectrum of epilepsy, we studied its main characteristics. METHODS: Based on clinical charts, we retrospectively analyzed the evolution of electroclinical features of 12 patients with confirmed MD. RESULTS: Epilepsy could be divided into three periods: (a) an early stage (median age, 3 months), characterized by focal clonic status epilepticus, usually triggered by fever (10 patients). Ictal EEG showed runs of slow spike-waves and slow waves in the posterior regions, and interictal EEG multifocal and polymorphic slow waves (three cases), or mixed slow spike-waves and slow waves (seven cases). Partial seizure control was obtained in nine patients during 5.9 months; (b) an intermediate stage (median age, 10 months) with intractable infantile spasms (11 patients) in which interictal EEG demonstrated modified hypsarrhythmia (seven cases), diffuse irregular slow waves and spike-waves (four cases). Six patients died at the median age of 15 months; and (c) a late stage in the six remaining patients (median age, 25 months), with multifocal seizures, tonic spasms, and myoclonus in four patients, whereas two patients became seizure free. Interictal EEG showed multifocal high-amplitude activity, mixed with irregular slow waves in all six cases. These patients died at the median age of 3.6 years. CONCLUSIONS: Based on a relatively large series of MD patients with a quite prolonged survival, we individualized three successive periods in the course of epilepsy: early focal status, then infantile spasms, and then myoclonic and multifocal epilepsy after age 2 years.

Adult↗

PubMed2006

Linkage analysis and disease models in benign familial infantile seizures: a study of 16 families.

PURPOSE: Benign familial infantile seizures (BFIS) is a genetically heterogeneous condition characterized by partial seizures, onset age from 3 to 9 months, and favorable outcome. BFIS loci were identified on chromosomes 19q12-13.1 and 16p12-q12, allelic to infantile convulsions and choreathetosis. The identification of SCN2A mutations in families with only infantile seizures indicated that BFNIS and BFIS may show overlapping clinical features. Infantile seizures also were in a family with familial hemiplegic migraine and mutations in the ATP1A2 gene. We have examined the heterogeneous genetics of BFIS by means of linkage analysis. METHODS: Sixteen families were examined. Probands underwent neurologic examination, at least one EEG recording, and, when possible, brain CT and MRI. Clinical information about relatives was collected. Families with SCN2A or ATP1A2 mutations were excluded from the study. Chromosome 16p and 19q loci were examined by linkage analysis using two models that differed in penetrance rate. Genetic heterogeneity was evaluated with both models. RESULTS: Clinical information was available for 124 members of affected families. BFIS was diagnosed in 69 subjects. One patient without BFIS had a single febrile seizure, and another had rare episodes of paroxysmal dystonia. Evidence of linkage was obtained only for chromosome 16. Moreover, the high penetrance allowed the identification of genetic heterogeneity. CONCLUSIONS: Our data confirm the relevance of the chromosome 16 locus in BFIS and suggest the presence of an additional locus. This study shows that the genetic model used affects the outcome of linkage analysis.

Brain↗

PubMed2006

Exploration of the genetic architecture of idiopathic generalized epilepsies.

PURPOSE: Idiopathic generalized epilepsy (IGE) accounts for approximately 20% of all epilepsies and affects about 0.2% of the general population. The etiology of IGE is genetically determined, but the complex pattern of inheritance suggests an involvement of a large number of susceptibility genes. The objective of the present study was to explore the genetic architecture of common IGE syndromes and to dissect out susceptibility loci predisposing to absence or myoclonic seizures. METHODS: Genome-wide linkage scans were performed in 126 IGE-multiplex families of European origin ascertained through a proband with idiopathic absence epilepsy or juvenile myoclonic epilepsy. Each family had at least two siblings affected by IGE. To search for seizure type-related susceptibility loci, linkage analyses were carried out in family subgroups segregating either typical absence seizures or myoclonic and generalized tonic-clonic seizures on awakening. RESULTS: Nonparametric linkage scans revealed evidence for complex and heterogeneous genetic architectures involving linkage signals at 5q34, 6p12, 11q13, 13q22-q31, and 19q13. The signal patterns differed in their composition, depending on the predominant seizure type in the families. CONCLUSIONS: Our results are consistent with heterogeneous configurations of susceptibility loci associated with different IGE subtypes. Genetic determinants on 11q13 and 13q22-q31 seem to predispose preferentially to absence seizures, whereas loci on 5q34, 6p12, and 19q13 confer susceptibility to myoclonic and generalized tonic-clonic seizures on awakening.

Chromosome Mapping↗

PubMed2004

Monogenic idiopathic epilepsies.

Major advances have recently been made in our understanding of the genetic bases of monogenic inherited epilepsies. Direct molecular diagnosis is now possible in numerous inherited symptomatic epilepsies. Progress has also been spectacular with respect to several idiopathic epilepsies that are caused by mutations in genes encoding subunits of ion channels or neurotransmitter receptors. Although these findings concern only a few families and sporadic cases, their potential importance is great, because these genes are implicated in a wide range of more common epileptic disorders and seizure types as well as some rare syndromes. Functional studies of these mutations, while leading to further progress in the neurobiology of the epilepsies, will help to refine genotype-phenotype relations and increase our understanding of responses to antiepileptic drugs. In this article, we review the clinical and genetic data on most of the idiopathic human epilepsies and epileptic contexts in which the association of epilepsy and febrile convulsions is genetically determined.

Animals↗

PubMed2004

Fever, genes, and epilepsy.

About 13% of patients with epilepsy have a history of febrile seizures (FS). Studies of familial forms suggest a genetic component to the epidemiological link. Indeed, in certain monogenic forms of FS, for which several loci have been reported, some patients develop epilepsy with a higher risk than in the general population. Patients with generalised epilepsy with febrile seizures plus (GEFS+) can have typical and isolated FS, FS lasting more beyond age 6 years, and subsequent afebrile (typically generalised) seizures. Mutations associated with GEFS+ were identified in genes for subunits of the voltage-gated sodium channel and the gamma2 subunit of the ligand-gated GABAA receptor. Screening for these genes in patients with severe myoclonic epilepsy in infancy showed de novo mutations of the alpha1 subunit of the voltage-gated sodium channel. Antecedent FS are commonly observed in temporal-lobe epilepsy (TLE). In sporadic mesial TLE-characterised by the sequence of complex FS in childhood, hippocampal sclerosis, and refractory temporal-lobe seizures-association studies suggested the role of several susceptibility genes. Work on some large pedigrees also suggests that FS and temporal-lobe seizures may have a common genetic basis, whether hippocampus sclerosis is present or not. The molecular defects identified in the genetic associations of FS and epileptic seizures are very attractive models to aid our understanding of epileptogenesis and susceptibility to seizure-provoking factors, especially fever.

Epilepsy↗

PubMed2003

Short-term nonhormonal and nonsteroid treatment in West syndrome.

PURPOSE: West syndrome (WS) is considered an age-dependent epileptic encephalopathy and also a particular type of electrical epileptic status. Short-term hormonal or steroid treatment of WS with good efficacy is reported in the literature. The aim of this retrospective multiinstitutional study was to evaluate the early discontinuation of nonhormonal and nonsteroid treatment for WS. METHODS: Twenty-two WS cases in which treatment was discontinued after a maximum of 6 months, were collected. Inclusion criteria were the presence of typical EEG hypsarrhythmia (HY) and video-EEG recorded epileptic spasms. Exclusion criteria were the presence of partial seizures or other seizure types before spasm onset. The patients were treated with vigabatrin (VGB) in 19 cases and nitrazepam (NTZ) in three. The dose range was 70-130 mg/kg/day for VGB and 0.7-1.5 mg/kg/day for NTZ. The drug was discontinued if spasms stopped and HY disappeared after a mean treatment period of 5.1 months (range, 3-6 months). All patients underwent repeated and prolonged awake and sleep video-EEG, both before and after drug discontinuation. RESULTS: Cryptogenic (15) and symptomatic (seven) WS patients were included. All the symptomatic cases had neonatal hypoxic-ischemic encephalopathy. The mean age at spasm onset was 5.5 months (range, 3-7 months; median, 6). The interval between spasm onset and drug administration ranged from 7 to 90 days (mean, 23 days; median, 20). The interval between drug administration and spasm disappearance ranged from 2 to 11 days (mean, 6 days; median, 6 days). The interval between drug administration and HY disappearance ranged from 3 to 30 days (mean, 9 days; median, 10 days). Drugs were stopped progressively over a 30- to 60-day period. Follow-up ranged from 13 to 50 months (mean, 26 months; median, 22 months). None of our cases showed spasm recurrence. CONCLUSIONS: Our data show that successful nonhormonal and nonsteroid treatment can be shortened to a few months without spasm recurrence in patients with cryptogenic or postanoxic WS.

Anticonvulsants↗

PubMed2002

A locus for simple pure febrile seizures maps to chromosome 6q22-q24.

Febrile seizures (FS) syndromes exhibit major clinical and genetic heterogeneity. We report a clinical and genetic study of three families with simple FS segregating as an autosomal dominant (AD) trait with high penetrance. All affected members presented a homogeneous phenotype of simple FS. The FS ceased before the age of 5 years. Among the 29 affected family members, only one patient presented two afebrile seizures, and none of the others developed concomitant or subsequent epilepsy. The phenotype differs from that previously reported in families presenting FS or generalized epilepsy with febrile seizures plus (GEFS+). After exclusion of already known loci for FS and GEFS+, we performed a genome-wide scan in the largest family. It led to the identification of a new locus on chromosome 6q22-q24 spanning 6.4 cM between D6S1620 and D6S975. For one of the other two families, the trait also segregated with this locus, but linkage studies could not restrict the candidate region further. The absence of linkage in the third family supports genetic heterogeneity of the AD form of pure simple FS. Sequence analysis excluded the implication of five candidate genes [A kinase anchoring protein 18 (AKAP18), syntaxin 7, putative neurotransmitter receptor (PNR), G protein receptor 57 (GPR57) and G protein receptor 58 (GPR58)] in the interval based on function. The locus mapping to 6q22-q24 seems to be the first identified locus responsible for pure simple FS, the most frequent form of FS. Studies are ongoing to identify the gene.

Adolescent↗

PubMedDate not supplied

Epileptic encephalopathies: a brief overview.

Epileptic encephalopathies are conditions in which neurologic deterioration is attributable entirely or partly to epileptic activity. It can be due to very frequent or severe seizures and/or to subcontinuous paroxysmal interictal activity. The former mainly consists of Dravet syndrome, in which patients have seizures from the middle of the first year of life and repeat episodes of severe febrile status epilepticus and migrating partial epilepsy in infancy, in which from the first trimester of life, partial seizures affect various areas of the cortex randomly and in a subcontinuous fashion. In Rasmussen syndrome, also, epileptic activity contributes at least partly to the neurologic deterioration. Subcontinuous paroxysmal interictal activity affects newborn infants with suppression bursts, thus consisting in either Ohtahara syndrome or neonatal myoclonic encephalopathy. In infants, it is either myoclonic epilepsy of nonprogressive encephalopathy or West syndrome. In school-age children, it consists of various types of generalized seizures combined with slow spike waves of the Lennox-Gastaut syndrome, myoclonic-astatic epilepsy, and continuous spike waves in slow sleep combined with various motor or cognitive deficits including negative myoclonus, orofacial dyspraxia, Landau-Kleffner syndrome, and frontal lobe syndrome. Treatment differs for all of these syndromes. It is important to avoid potential drug-induced worsening, and valproate is preferred when a definitive diagnosis is not reached in children and especially infants.

Electroencephalography↗