Petra M.C. Callenbach

Mutations in DEPDC5 cause familial focal epilepsy with variable foci

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.

Familial Occurrence of Epilepsy in Children with Newly Diagnosed Multiple Seizures: Dutch Study of Epilepsy in Childhood

Summary: Purpose: To study the familial occurrence of epilepsy in children with newly diagnosed multiple unprovoked seizures.

Familial cortical myoclonic tremor with epilepsy : A single syndromic classification for a group of pedigrees bearing common features

Fifty Japanese and European families with cortical myoclonic tremor and epilepsy have been reported under various names. Unfamiliarity with the syndrome often leads to an initial misdiagnosis of essential tremor or progressive myoclonus epilepsy. A detailed overview of the literature is lacking and is the scope of this study. Disease characteristics are adult onset, distal action tremor and myoclonus, epileptic seizures, autosomal dominant inheritance, benign course, effectiveness of antiepileptic drugs, and possibly cognitive decline. A channelopathy is hypothesized to be the basis of the disease. Despite phenotypic and genetic differences between the Japanese and European pedigrees, the clinical and electrophysiological data point toward one syndrome. To avoid confusion in literature and possible misdiagnosis of patients, we propose to use one description and suggest “familial cortical myoclonic tremor with epilepsy” (FCMTE). In addition, we put forward diagnostic criteria to give a starting point from which to conduct genetic studies.

Mortality Risks in New-Onset Childhood Epilepsy

OBJECTIVES: Estimate the causes and risk of death, specifically seizure related, in children followed from onset of epilepsy and to contrast the risk of seizure-related death with other common causes of death in the population. METHODS: Mortality experiences from 4 pediatric cohorts of newly diagnosed patients were combined. Causes of death were classified as seizure related (including sudden unexpected death [SUDEP]), natural causes, nonnatural causes, and unknown. RESULTS: Of 2239 subjects followed up for >30 000 person-years, 79 died. Ten subjects with lethal neurometabolic conditions were ultimately excluded. The overall death rate (per 100 000 person-years) was 228; 743 in complicated epilepsy (with associated neurodisability or underlying brain condition) and 36 in uncomplicated epilepsy. Thirteen deaths were seizure-related (10 SUDEP, 3 other), accounting for 19% of all deaths. Seizure-related death rates were 43 overall, 122 for complicated epilepsy, and 14 for uncomplicated epilepsy. Death rates from other natural causes were 159, 561, and 9, respectively. Of 48 deaths from other natural causes, 37 were due to pneumonia or other respiratory complications. CONCLUSIONS: Most excess death in young people with epilepsy is not seizure-related. Mortality is significantly higher compared with the general population in children with complicated epilepsy but not uncomplicated epilepsy. The SUDEP rate was similar to or higher than sudden infant death syndrome rates. In uncomplicated epilepsy, sudden and seizure-related death rates were similar to or higher than rates for other common causes of death in young people (eg, accidents, suicides, homicides). Relating the risk of death in epilepsy to familiar risks may facilitate discussions of seizure-related mortality with patients and families.

Familial partial epilepsy with variable foci in a Dutch family: clinical characteristics and confirmation of linkage to chromosome 22q.

Summary:  Purpose: Three forms of idiopathic partial epilepsy with autosomal dominant inheritance have been described: (a) autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE); (b) autosomal dominant lateral temporal epilepsy (ADLTE) or partial epilepsy with auditory features (ADPEAF); and (c) familial partial epilepsy with variable foci (FPEVF). Here we describe linkage analysis in a Dutch four‐generation family with epilepsy fulfilling criteria of both ADNFLE and FPEVF.

Linkage and mutational analysis of CLCN2 in childhood absence epilepsy

In order to assess the chloride channel gene CLCN2 as a candidate susceptibility gene for childhood absence epilepsy, parametric and non-parametric linkage analysis was performed in 65 nuclear pedigrees. This provided suggestive evidence for linkage with heterogeneity: NPL score=2.3, p<0.009; HLOD=1.5, alpha=0.44. Mutational analysis of the entire genomic sequence of CLCN2 was performed in 24 unrelated patients from pedigrees consistent with linkage, identifying 45 sequence variants including the known non-synonymous polymorphism rs2228292 (G2154C, Glu718Asp) and a novel variant IVS4+12G>A. Intra-familial association analysis using the pedigrees and a further 308 parent-child trios showed suggestive evidence for transmission disequilibrium of the G2154C minor allele: AVE-PDT chi(1)2 = 5.17, p<0.03. Case-control analysis provided evidence for a protective effect of the IVS4+12G>A minor allele: chi(1)2 = 7.27, p<0.008. The 65 nuclear pedigrees were screened for three previously identified mutations shown to segregate with a variety of idiopathic generalised epilepsy phenotypes (597insG, IVS2-14del11 and G2144A) but none were found. We conclude that CLCN2 may be a susceptibility locus in a subset of cases of childhood absence epilepsy.

Long term outcome of benign childhood epilepsy with centrotemporal spikes: Dutch Study of Epilepsy in Childhood

PURPOSE To determine long-term outcome in a cohort of children with newly diagnosed benign childhood epilepsy with centrotemporal spikes (BECTS). METHODS 29 children with BECTS were included in the Dutch Study of Epilepsy in Childhood. Each child was followed for 5 years, and subsequently contacted 12-17 years after enrolment to complete a structured questionnaire. Twenty children had typical BECTS, nine had atypical BECTS (age at onset <4 years, developmental delay or learning difficulties at inclusion, other seizure types, atypical EEG abnormalities). RESULTS Mean age at onset of epilepsy was 8.0 years with slight male preponderance. Most common seizure-types before enrolment were generalized tonic-clonic seizures (GTCS) and simple partial seizures; in 86% of the children seizures occurred during sleep. After 12-17 years, 96% had a terminal remission (TR(F)) of more than 5 years and 89% of more than 10 years. Mean duration of epilepsy was 2.7 years; mean age at reaching TR(F) was 10.6 years. Many children (63%) had experienced one or more (secondary) GTCS. Antiepileptic drugs were used by 79% of the children with a mean duration of 3.0 years. None of the children seemed to have developed learning problems or an arrest of cognitive development during follow-up. No significant differences were observed in patient characteristics or outcome between children with typical BECTS and children with atypical BECTS. CONCLUSIONS All children in our cohort, both those with typical and atypical BECTS, had a very good prognosis with high remission rates after 12-17 years. None of the predictive factors for disease course and outcome observed in earlier studies (other seizure types, age at onset, multiple seizures at onset) were prognostic in our cohort.

Long-term outcome of childhood absence epilepsy: Dutch Study of Epilepsy in Childhood

SUMMARY We determined long-term outcome and the predictive value of baseline and EEG characteristics on seizure activity evolution in 47 children with newly diagnosed childhood absence epilepsy (CAE) included in the Dutch Study of Epilepsy in Childhood. All children were followed for 12-17 years. The children were subdivided in three groups for the analyses: those becoming seizure-free (I) within 1 month after enrolment; (II) 1-6 months after enrolment; and (III) more than 6 months after enrolment or having seizures continuing during follow-up. No significant differences were observed between groups in sex, age at onset, occurrence of febrile seizures, and positive first-degree family history for epilepsy. All groups had high remission rates after 12-17 years. Significantly more relapses occurred in group III than in group I. Total duration of epilepsy and mean age at final remission were 3.9 and 9.5 years, respectively, being significantly longer and higher in group III than in groups I and II. In all groups only a small number of children (total 13%) developed generalized tonic-clonic seizures. In conclusion, our children with CAE had an overall good prognosis with few children (7%) still having seizures after 12-17 years. Remission rate in children with CAE cannot be predicted on the basis of baseline and EEG characteristics. The early clinical course (i.e. the first 6 months) has some predictive value with respect to the total duration of absence epilepsy.

A Dutch family with 'familial cortical tremor with epilepsy' - Clinical characteristics and exclusion of linkage to chromosome 8q23.3-q24.1

Abstract.Objectives: To describe the clinical characteristics of a large Dutch family with cortical tremor with epilepsy (FCTE) and to test for genetic linkage of FCTE to chromosome 8q23.3–q24.1. Background: FCTE is an idiopathic generalised epilepsy of adult onset with autosomal dominant inheritance. It is characterised by kinesiogenic tremor and myoclonus of the limbs, generalised seizures, and electrophysiological findings consistent with cortical reflex myoclonus. Genetic analysis has been performed in five Japanese families. In all families, linkage was shown to chromosome 8q23.3–q24.1. Methods: Clinical and electrophysiological data of a four-generation family, suspected of autosomal dominant inherited FCTE, were collected and linkage analysis was performed. Results Clinical and electrophysiological findings were consistent with a diagnosis of FCTE. Of 41 relatives examined, 13 subjects were considered to be definitely affected, three were probably affected and ten were unaffected. In 15 relatives, the diagnosis could not be established. Linkage to chromosome 8q23.3–q24.1 was excluded. Conclusions: In this family with autosomal dominant FCTE, specific clinical and electrophysiological features were identified. Exclusion of linkage to chromosome 8q23.3–q24.1 indicates that genetic heterogeneity exists for FCTE.

Whole-genome linkage scan for epilepsy-related photosensitivity: a mega-analysis.

Photoparoxysmal response (PPR) is considered to be a risk factor for idiopathic generalised epilepsy (IGE) and it has a strong genetic basis. Two genome-wide linkage studies have been published before and they identified loci for PPR at 6p21, 7q32, 13q13, 13q31 and 16p13. Here we combine these studies, augmented with additional families, in a mega-analysis of 100 families. Non-parametric linkage analysis identified three suggestive peaks for photosensitivity, two of which are novel (5q35.3 and 8q21.13) and one has been found before (16p13.3). We found no evidence for linkage at four previously detected loci (6p21, 7q32, 13q13 and 13q31). Our results suggest that the different family data sets are not linked to a shared locus. Detailed analysis showed that the peak at 16p13 was mainly supported by a single subset of families, while the peaks at 5q35 and 8q21 had weak support from multiple subsets. Family studies clearly support the role of PPR as a risk factor for IGE. This mega-analysis shows that distinct loci seem to be linked to subsets of PPR-positive families that may differ in subtle clinical phenotypes or geographic origin. Further linkage studies of PPR should therefore include in-depth phenotyping to make appropriate subsets and increase genetic homogeneity.