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Samuel F Berkovic

Publications and source records attributed to Samuel F Berkovic.

At least 55 records · Page 3Linked to original sources
PubMed2004

Genetic association studies in epilepsy: "the truth is out there".

Success has been achieved in identifying many mutations in rare monogenic epilepsy syndromes by using linkage analysis, but dissecting the genetic basis of common epilepsy syndromes has proven more difficult. Common epilepsies are genetically complex disorders believed to be influenced by variation in several susceptibility genes. Association studies can theoretically identify these genes, but despite more than 50 association studies in epilepsy, no consistent or convincing susceptibility genes have emerged, leading to scepticism about the association-study approach. We review the results of existing association studies in focal epilepsies, generalized epilepsies, febrile seizures, and epilepsy pharmacogenetics. By using an illustrative example, we discuss how methodologic issues of sample size, selection of appropriate controls, population stratification, and significance thresholds can lead to bias and false-positive associations; the importance of biologic plausibility also is emphasized. Newer methodologic refinements for association studies, such as use of two control groups, genomic control, haplotyping, and use of two independent datasets, are discussed. A summary of existing guidelines and a checklist for planning and appraising such association studies in epilepsy is presented. We remain cautiously optimistic that with methodologic refinements and multicenter collaborations with large sample sizes, association studies will ultimately be useful in dissecting the genetic basis of common epilepsy syndromes.

Chromosome Mapping↗
PubMed2004

Familial partial epilepsy with variable foci: clinical features and linkage to chromosome 22q12.

BACKGROUND: Familial partial epilepsy with variable foci (FPEVF) is an autosomal dominant syndrome characterized by partial seizures originating from different brain regions in different family members in the absence of detectable structural abnormalities. A gene for FPEVF was mapped to chromosome 22q12 in two distantly related French-Canadian families. METHODS: We describe the clinical features and performed a linkage analysis in a Spanish kindred and in a third French-Canadian family distantly related to the original pedigrees. RESULTS: Onset of seizures was typically in middle childhood, and attacks were usually easy to control. Seizure semiology varied among family members but was constant for each individual. In some, a pattern of nocturnal frontal lobe seizures led to consideration of the diagnosis of autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). The Spanish family was mapped to chromosome 22q (multipoint lod score, 3.4), and the new French-Canadian family had a multipoint lod score of 2.97 and shared the haplotype of the original French-Canadian families. CONCLUSIONS: Identification of the various forms of familial partial epilepsy is challenging, particularly in small families, in which insufficient individuals exist to identify a specific pattern. We provide clinical guidelines for this task, which will eventually be supplanted by specific molecular diagnosis. We confirmed linkage of FPEVF to chromosome 22q12 and redefined the region to a 5.2-Mb segment of DNA.

Adolescent↗
PubMed2004

Genetic architecture of idiopathic generalized epilepsy: clinical genetic analysis of 55 multiplex families.

PURPOSE: In families with idiopathic generalized epilepsy (IGE), multiple IGE subsyndromes may occur. We performed a genetic study of IGE families to clarify the genetic relation of the IGE subsyndromes and to improve understanding of the mode(s) of inheritance. METHODS: Clinical and genealogic data were obtained on probands with IGE and family members with a history of seizures. Families were grouped according to the probands' IGE subsyndrome: childhood absence epilepsy (CAE), juvenile absence epilepsy (JAE), juvenile myoclonic epilepsy (JME), and IGE with tonic-clonic seizures only (IGE-TCS). The subsyndromes in the relatives were analyzed. Mutations in genes encoding alpha1 and gamma 2 gamma-aminobutyric acid (GABA)-receptor subunits, alpha1 and beta1 sodium channel subunits, and the chloride channel CLC-2 were sought. RESULTS: Fifty-five families were studied. 122 (13%) of 937 first- and second-degree relatives had seizures. Phenotypic concordance within families of CAE and JME probands was 28 and 27%, respectively. JAE and IGE-TCS families had a much lower concordance (10 and 13%), and in the JAE group, 31% of relatives had CAE. JME was rare among affected relatives of CAE and JAE probands and vice versa. Mothers were more frequently affected than fathers. No GABA-receptor or sodium or chloride channel gene mutations were identified. CONCLUSIONS: The clinical genetic analysis of this set of families suggests that CAE and JAE share a close genetic relation, whereas JME is a more distinct entity. Febrile seizures and epilepsy with unclassified tonic-clonic seizures were frequent in affected relatives of all IGE individuals, perhaps representing a nonspecific susceptibility to seizures. A maternal effect also was seen. Our findings are consistent with an oligogenic model of inheritance.

Adolescent↗
PubMed2004

Subtle microscopic abnormalities in hippocampal sclerosis do not predict clinical features of temporal lobe epilepsy.

PURPOSE: Subtle microdysplastic features are found in some patients with hippocampal sclerosis (HS) and refractory temporal lobe epilepsy. The significance of these findings is unknown. We investigated their frequency, relation to the pattern of HS, and clinical associations. METHODS: One-hundred forty patients with histologically confirmed HS (mean age at operation, 35 years; 85 women) were analyzed. The presence of HS and subtle structural abnormalities (SSAs) in the mesial temporal lobe and in the lateral neocortical tissue was assessed in detail. Antecedents, seizure characteristics, two verbal memory tests, and outcome in HS patients with and without SSAs were determined. RESULTS: SSAs were found in 60 (43%) of the 140 HS patients, being mesial only in 32 of the 60 cases, and lateral only in nine cases; the remaining 19 cases had both mesial and lateral abnormalities. The frequency of SSA was not related to the pattern of HS or other tested variables. Prolonged febrile convulsions were present in 26 (44%) patients with SSAs, and in 26 (34%) patients (not significant) without SSAs. The outcome after surgery did not differ between patients with SSAs (incidence rate ratio for seizure recurrence, 0.9; 95% confidence interval, 0.5-1.6) compared with patients without SSAs (reference ratio, 1). CONCLUSIONS: Forty-three percent of HS patients have SSAs in their lobectomy specimens. The presence of SSAs does not predict clinical characteristics, such as presence of prolonged febrile convulsions, postsurgical outcome, or neuropsychological performance, nor does it correlate with the histologic pattern of HS.

Adult↗
PubMed2004

MR imaging and spectroscopic study of epileptogenic hypothalamic hamartomas: analysis of 72 cases.

BACKGROUND AND PURPOSE: Reports of MR imaging in hypothalamic hamartomas associated with epilepsy are few, and the number of patients studied is small. We aimed to detail the relationship of hypothalamic hamartomas to surrounding structures, to determine the frequency and nature of associated abnormalities, and to gain insight into mechanisms of epileptogenesis. METHODS: We systematically examined MR imaging studies of 72 patients with hypothalamic hamartoma and refractory epilepsy (patient age, 22 months to 31 years). A dedicated imaging protocol was used in 38 cases. Proton MR spectroscopy of the hypothalamic hamartoma was performed for 19 patients and compared with the metabolite profile of the thalamus in 10 normal children and the frontal lobe in 10 normal adults. RESULTS: Compared with normal gray matter, hypothalamic hamartomas were hyperintense on T2-weighted images (93%), hypointense on T1-weighted images (74%), and had reduced N-acetylaspartate and increased myoinositol content shown by MR spectroscopy. Hypothalamic hamartomas always involved the mammillary region of the hypothalamus, with attachment to one or both mammillary bodies. Intrahypothalamic extension (noted in 97%) tended to displace the postcommissural fornix and hypothalamic gray matter anterolaterally, such that the hypothalamic hamartomas nestled between the fornix, the mammillary body, and the mammillothalamic tract. Larger hamartoma size was associated with central precocious puberty. Associated findings of questionable epileptic significance included anterior temporal white matter signal intensity abnormalities (16%) and arachnoid cysts (6%). Malformations of cortical development were observed in only two patients, and hippocampal sclerosis was not observed. CONCLUSIONS: Hypothalamic hamartomas can be readily distinguished from normal hypothalamic gray and adjacent myelinated fiber tracts, best appreciated on thin T2-weighted images. MR imaging and spectroscopy suggest reduced neuronal density and relative gliosis compared with normal gray matter. Associated epileptogenic lesions are rare, supporting the view that the hypothalamic hamartoma alone is responsible for the typical clinical features of the syndrome. The intimate relationship to the mammillary body, fornix, and mammillothalamic tract suggests a role for these structures in epileptogenesis associated with hypothalamic hamartomas.

Adolescent↗
PubMed2004

Sandifer syndrome misdiagnosed as refractory partial seizures in an adult.

We report a 27 year-old man with intellectual disability and no prior history of seizures who presented with episodes of abdominal pain, head/eye version and unresponsiveness that were misdiagnosed and treated as partial seizures. Associated vomiting and haematemesis led to the correct diagnosis and treatment of reflux oesophagitis. The episodes immediately resolved and a diagnosis of Sandifer syndrome was made. This is only the second report of Sandifer syndrome in adult, a movement disorder of unknown mechanism that occurs almost exclusively in young children, often misdiagnosed as epilepsy or episodic dystonia. (Published with videosequences).

Adult↗
PubMed2004

Temporal lobe dysembryoplastic neuroepithelial tumour: significance of discordant interictal spikes.

PURPOSE: Dysembryoplastic neuroepithelial tumours (DNET) are an important cause of refractory partial epilepsies. They usually occur within dysplastic cortex and tend to affect the temporal lobes. The EEG of these patients is characterised by slowing and/or epileptiform abnormalities with a multifocal distribution. We studied the EEG features of epilepsy patients with a temporal lobe DNET to assess the relationship of EEG abnormalities with the localisation of the tumour and the clinical features. METHODS: We retrospectively reviewed 16 patients with unilateral, temporal lobe DNET on MRI. The EEG abnormalities were classified as concordant to the lesion when the EEG discharges were confined to the ipsilateral temporal lobe or discordant when EEG discharges were found in other areas. Clinical and epilepsy characteristics were compared between patients with concordant and discordant EEG. RESULTS: Focal EEG abnormalities were found in 81% of the patients; 6/16 patients had concordant EEG abnormalities, and 7/16 patients had discordant EEG abnormalities. Epilepsy severity prior to the operation, antecedents and post-operative outcome were not different between patients with concordant or discordant EEG abnormalities. CONCLUSION: Patients with temporal lobe DNET often show EEG discharges discordant to the tumour. However, they do not appear to predict the clinical and epilepsy characteristics of these patients.

Adult↗
PubMed2003

The genetics of human epilepsy.

In recent years genetic discoveries have shown the central role of ion channels in the pathophysiology of idiopathic epilepsies. Uncommon epilepsy syndromes that have monogenic inheritance are associated with mutations in genes that encode subunits of voltage-gated and ligand-gated ion channels. For voltage-gated ion channels, mutations of Na(+), K(+) and Cl(-) channels are associated with forms of generalized epilepsy and infantile seizure syndromes. Ligand-gated ion channels, such as nicotinic acetylcholine receptors and GABA receptor subunits, are associated with specific syndromes of frontal and generalized epilepsies, respectively. Striking features are the variable epilepsy phenotypes that are associated with the known gene mutations and the genetic heterogeneity that underlies all known monogenic syndromes. Mutations in two genes that do not encode ion channels have been identified in the idiopathic human epilepsies. The heterogeneity of mutations described to date has precluded the development of simple diagnostic tests, but advances in the next few years are likely to have an impact on both the clinical diagnosis and the treatment of epilepsies.

Calcium Channels↗
PubMed2003

Risk factors for sudden unexpected death in epilepsy: a controlled prospective study based on coroners cases.

We performed a controlled prospective study of pathologically verified sudden unexpected death in epilepsy (SUDEP) in a coronial setting, to identify risk factors. We prospectively studied coronial deaths of people with epilepsy in Vic., Australia, during a 21-month period. Fifty SUDEP and 50 subjects with epilepsy who died of other causes (controls) were collected sequentially. Clinical data was obtained shortly after death from questionnaires completed by treating doctors, discussion with family members and coronial files, including police reports of death, autopsy and toxicology reports. Factors assessed were age, sex, duration of epilepsy, type of seizure(s), seizure frequency, symptomatic epilepsy, including post-traumatic epilepsy, presence of structural brain lesion, idiopathic epilepsy, mental retardation, psychiatric illness, including dementia, recent stressful life event, particular antiepileptic drugs (AEDs) and AED polytherapy, compliance with AED treatment, psychotropic drug prescription, alcohol and other substance abuse, place of death and evidence of terminal seizure. The SUDEP group was characterised by younger age and higher proportion found dead in bed and with evidence of terminal seizure compared to controls. The profile of patients at risk for SUDEP are young people with epilepsy. They are most likely to die in sleep and our data support the view that SUDEP is a seizure-related event. This, taken in conjunction with the finding that there was no increased risk associated with a particular AED in monotherapy or multiple AEDs suggests that attempts to better treat patients' epilepsy with AEDs might decrease the risk of SUDEP. Although the literature suggests that SUDEP is more frequent in patients with severe epilepsy, we did not find a correlation with seizure frequency suggesting that other clinical indices may be more important.

Adolescent↗
PubMed2003

Epilepsy in offspring of whom both parents have idiopathic generalized epilepsy: biparental inheritance.

BACKGROUND: Little is known about offspring of parents who both have idiopathic generalized epilepsy (IGE). This is of importance for understanding the complex genetic architecture of IGE. METHODS: Families in whom both parents had proven IGE were ascertained through a multiplex families database. Clinical information including EEG recordings and detailed pedigrees was obtained. RESULTS: In family I, the mother had juvenile myoclonic epilepsy (JME), and the father had IGE. One daughter had Lennox-Gastaut syndrome, and the other had unclassified epilepsy. In family II, the mother had JME, and the father had IGE. Two of three sons had an identical clinical picture of clinical picture of childhood absence epilepsy (CAE), but with fast polyspike-wave discharges on EEG. CONCLUSIONS: The clinical phenotype of affected offspring suggested that their epilepsy could be due to the combination of a putative "double dose" of genes from both sides of the family. In such families, as epilepsy genes could be inherited from both parents, a high risk of epilepsy in the offspring could be expected.

Adult↗
PubMed2003

Phenotypic comparison of two Scottish families with mutations in different genes causing autosomal dominant nocturnal frontal lobe epilepsy.

PURPOSE: Mutations in genes coding for the alpha 4 and beta 2 subunits of the neuronal nicotinic acetylcholine receptor receptor (CHRN) are known to cause autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Here we examined the phenotypes in two families, from the same ethnic and geographic backgrounds, with ADNFLE as a result of mutations in these two different subunits of CHRN. METHODS: All affected family members underwent a detailed clinical evaluation and review of available EEG, neuroimaging, and videotapes of seizures. The molecular study of family D is reported here; family S has a previously reported mutation in the beta 2 subunit of CHRN. RESULTS: A total of 16 individuals with ADNFLE were identified in the two families. In both families, seizure semiology, age at seizure onset, and the natural history of the seizure disorder was similar. Intrafamilial variation in terms of severity of epilepsy syndrome was present in both families. A significant number of individuals from each family had a history of psychological problems. The molecular study of family D revealed a Ser248Phe mutation in the alpha 4 subunit of CHRN. CONCLUSIONS: The epilepsy phenotype is not distinguishable in the two families who have ADNFLE as a result of mutations in genes coding for different CHRN subunits. This is likely to be due to the similar functional consequences of each mutation on the CHRN receptor.

Adolescent↗
PubMed2003

EEG in adult-onset idiopathic generalized epilepsy.

PURPOSE: It remains controversial whether adult-onset idiopathic generalized epilepsy (IGE) is a distinct syndrome or a continuum among IGE syndromes. EEG is the only known biologic marker of IGE and helps differentiate many of its classic subsyndromes. In this study, we looked for the differences in the EEG findings of IGE of classic adolescent onset versus adult onset that may suggest syndromic heterogeneity. METHODS: Seventy-six patients (47 adolescent-onset IGE, 29 adult-onset IGE) with a clinical and EEG diagnosis of IGE were included. We defined IGE with age at onset of 11-20 years as adolescent-onset IGE and age at onset of 20 years or after as adult-onset IGE. Patients with first-decade onset of seizures, delayed EEGs, and no EEG available for review were excluded. The first EEG was performed within 24 h of the seizure, and if negative, a sleep-deprived EEG was done. All EEGs were reviewed in detail with respect to the background activity and the generalized spike-wave (GSW) characteristic. RESULTS: EEGs (87; 56 adolescent-onset IGE, 31 adult-onset IGE) were systematically reviewed. Background was normal in all patients. The morphology, amplitude, duration, frequency, occurrence, or activation of the GSW pattern did not differ between these two groups. CONCLUSIONS: No differences of EEG features were found between the classic adolescent-onset and the adult-onset IGE. This supports the hypothesis that they share common biologic determinants and exist along a life-long age spectrum of classic IGE.

Adolescent↗
PubMed2003

Hypothalamic hamartoma and seizures: a treatable epileptic encephalopathy.

Hypothalamic hamartomas may be associated with gelastic seizures, focal seizures, and a generalized epileptic encephalopathy, with severe seizures and cognitive and behavior decline. Despite earlier views to the contrary, good evidence now exists that all these clinical features are caused, directly or indirectly, by the hamartoma. Resection of these lesions was long regarded as too hazardous and unlikely to benefit seizure control. It is now clear that hypothalamic hamartomas can be effectively treated with a variety of surgical approaches with sustained seizure control and often seizure freedom. Qualitative observations suggest that behavior and cognition also improve with treatment, but quantitative validation is required. The specific approach should be tailored according to the surgical anatomy of the lesion and the experience of the surgeon. Choices include a transcallosal approach (good for intraventricular lesions), a pterional approach (useful for interpeduncular lesions), a transventricular endoscopic approach, or destruction of the lesion with radiofrequency probes or gamma knife radiosurgery. The previously dismal outlook for children with severe seizures associated with this lesion has now dramatically changed. These insights may have implications for other epileptic encephalopathies of childhood.

Adolescent↗
PubMed2003

Childhood absence epilepsy and febrile seizures: a family with a GABA(A) receptor mutation.

Although several genes for idiopathic epilepsies from families with simple Mendelian inheritance have been found, genes for the common idiopathic generalized epilepsies, where inheritance is complex, presently are elusive. We studied a large family with epilepsy where the two main phenotypes were childhood absence epilepsy (CAE) and febrile seizures (FS), which offered a special opportunity to identify epilepsy genes. A total of 35 family members had seizures over four generations. The phenotypes comprised typical CAE (eight individuals); FS alone (15), febrile seizures plus (FS(+)) (three); myoclonic astatic epilepsy (two); generalized epilepsy with tonic-clonic seizures alone (one); partial epilepsy (one); and unclassified epilepsy despite evaluation (two). In three remaining individuals, no information was available. FS were inherited in an autosomal dominant fashion with 75% penetrance. The inheritance of CAE in this family was not simple Mendelian, but suggestive of complex inheritance with the involvement of at least two genes. A GABA(A) receptor gamma2 subunit gene mutation on chromosome 5 segregated with FS, FS(+) and CAE, and also occurred in individuals with the other phenotypes. The clinical and molecular data suggest that the GABA(A) receptor subunit mutation alone can account for the FS phenotype. An interaction of this gene with another gene or genes is required for the CAE phenotype in this family. Linkage analysis for a putative second gene contributing to the CAE phenotype suggested possible loci on chromosomes 10, 13, 14 and 15. Examination of these loci in other absence pedigrees is warranted.

Adult↗
PubMed2003

Occipital epilepsies: identification of specific and newly recognized syndromes.

Occipital epilepsies often elude diagnosis as they frequently masquerade as other seizure syndromes. Visual hallucinations are the key clinical symptoms indicating an occipital focus, but may be difficult to elicit on history, especially from children, and are not always present. When visual symptoms are not prominent, the seizure semiology and scalp EEG may lead the clinician away from considering an occipital focus, as they often reflect seizure propagation rather than seizure origin. Clinical and neuroimaging advances have led to the recognition of many new occipital epilepsy syndromes, which generally present in childhood or adolescence. Major groups include malformations of cortical development [focal cortical dysplasia, periventricular heterotopia (PVH), subcortical band heterotopia (SBH), polymicrogyria], vascular (including epilepsy with bilateral occipital calcifications often associated with coeliac disease), metabolic and the emerging idiopathic occipital epilepsies. The idiopathic occipital epilepsies now comprise three identifiable electroclinical syndromes of childhood and adolescence, the biological inter-relationships and overlap with idiopathic generalized epilepsies of which are discussed here. We emphasize the clues to recognition of specific occipital epilepsies, some of which now have specific treatments. Where medical therapy is ineffective, occipital corticectomy should be considered. Emerging evidence suggests that some syndromes have a good surgical outcome, and the consequences to visual function may be less severe than anticipated.

Cerebral Cortex↗
PubMed2003

Channelopathies as a genetic cause of epilepsy.

PURPOSE OF REVIEW: This review describes the significant number of new gene associations with epilepsy syndromes that have emerged during the past year, together with additional mutations and new electrophysiological data relating to previously known gene associations. RECENT FINDINGS: Autosomal dominant juvenile myoclonic epilepsy was demonstrated to be a channelopathy associated with a GABA(A) receptor, alpha1 subunit mutation. Benign familial neonatal infantile seizures were delineated as another channelopathy of infancy, by molecular characterization of sodium channel, alpha2 subunit defects. A sodium channel, alpha2 subunit defect was previously found to be associated with generalized epilepsy with febrile seizures plus. Similarly, the clinical spectrum associated with potassium channel, KQT-like mutations was extended to include the channelopathy myokymia and neonatal epilepsy. Mutations in the non-ion channel genes, leucine-rich, glioma inactivated 1 gene and Aristaless related homeobox gene, have emerged as important causes of their specific syndromes, with mutations in the latter gene frequently underlying X-linked mental retardation with epilepsy. SUMMARY: All but one of the idiopathic epilepsies with a known molecular basis are channelopathies. Where the ion channel defects have been identified, however, they generally account for a minority of families and sporadic cases with the syndrome in question. The data suggest that ion channel mutations of large effect are a common cause of rare monogenic idiopathic epilepsies, but are rare causes of common epilepsies. Additive effects of genetic variation, perhaps within the same ion channel gene families, are likely to underlie the common idiopathic generalized epilepsies with complex inheritance. The genetics of epilepsy is progressing rapidly toward a more detailed molecular dissection and definition of syndromes.

Calcium Channels↗
PubMed2003

A twin study of genetic influences on epilepsy outcome.

The identification of genetic factors that confer susceptibility to the epilepsies has to date been the focus of genetic efforts in this field. Few studies have assessed the genetic contribution to disease course in epilepsy, yet an understanding of the genetic influences on epilepsy outcome is key to developing new therapeutic strategies. The aim of this study was to assess the genetic contributions to epilepsy outcome in twin pairs concordant for epilepsy. We studied 37 epilepsy concordant twin pairs (27 monozygotic, 10 dizygotic) in whom there were no recognized environmental contributions (e.g., acquired brain injury) to epilepsy, and in whom the most likely cause for epilepsy was a shared genetic susceptibility. Clinical outcome was determined using the binary measure of Seizure Status (seizure remission or recurrence) and on a six-category ordinal Outcome Scale. Epilepsy outcome was independent of age of seizure onset, age at assessment and major epilepsy syndrome diagnosis. The proportion of twin pairs concordant for Seizure Status was 0.81 (22/27) for monozygous and 1.0 (10/10) for dizygous pairs, p = 0.3. Within-pair correlation in outcome (Outcome Scale) was 0.60 (95% CI: 0.32, 0.78) in monozygous and 0.78 (0.48, 0.92) in dizygous pairs. These data provide no evidence for genetic influences on epilepsy outcome independent of those that contribute to disease susceptibility. The observed high correlations for outcome suggest that, for epilepsy, susceptibility genes also have a major influence on outcome.

Chi-Square Distribution↗