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A recurrent de novo mutation in KCNC1 causes progressive myoclonus epilepsy

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.

Genome-wide association analysis of genetic generalized epilepsies implicates susceptibility loci at 1q43, 2p16.1, 2q22.3 and 17q21.32

Genetic generalized epilepsies (GGEs) have a lifetime prevalence of 0.3% and account for 20-30% of all epilepsies. Despite their high heritability of 80%, the genetic factors predisposing to GGEs remain elusive. To identify susceptibility variants shared across common GGE syndromes, we carried out a two-stage genome-wide association study (GWAS) including 3020 patients with GGEs and 3954 controls of European ancestry. To dissect out syndrome-related variants, we also explored two distinct GGE subgroups comprising 1434 patients with genetic absence epilepsies (GAEs) and 1134 patients with juvenile myoclonic epilepsy (JME). Joint Stage-1 and 2 analyses revealed genome-wide significant associations for GGEs at 2p16.1 (rs13026414, P(meta) = 2.5 × 10(-9), OR[T] = 0.81) and 17q21.32 (rs72823592, P(meta) = 9.3 × 10(-9), OR[A] = 0.77). The search for syndrome-related susceptibility alleles identified significant associations for GAEs at 2q22.3 (rs10496964, P(meta) = 9.1 × 10(-9), OR[T] = 0.68) and at 1q43 for JME (rs12059546, P(meta) = 4.1 × 10(-8), OR[G] = 1.42). Suggestive evidence for an association with GGEs was found in the region 2q24.3 (rs11890028, P(meta) = 4.0 × 10(-6)) nearby the SCN1A gene, which is currently the gene with the largest number of known epilepsy-related mutations. The associated regions harbor high-ranking candidate genes: CHRM3 at 1q43, VRK2 at 2p16.1, ZEB2 at 2q22.3, SCN1A at 2q24.3 and PNPO at 17q21.32. Further replication efforts are necessary to elucidate whether these positional candidate genes contribute to the heritability of the common GGE syndromes.

Diet restriction in migraine, based on IgG against foods: A clinical double-blind, randomised, cross-over trial

Introduction: It is well-known that specific foods trigger migraine attacks in some patients. We aimed to investigate the effect of diet restriction, based on IgG antibodies against food antigens on the course of migraine attacks in this randomised, double blind, cross-over, headache-diary based trial on 30 patients diagnosed with migraine without aura. Methods: Following a 6-week baseline, IgG antibodies against 266 food antigens were detected by ELISA. Then, the patients were randomised to a 6-week diet either excluding or including specific foods with raised IgG antibodies, individually. Following a 2-week diet-free interval after the first diet period, the same patients were given the opposite 6-week diet (provocation diet following elimination diet or vice versa). Patients and their physicians were blinded to IgG test results and the type of diet (provocation or elimination). Primary parameters were number of headache days and migraine attack count. Of 30 patients, 28 were female and 2 were male, aged 19–52 years (mean, 35 ± 10 years). Results: The average count of reactions with abnormally high titre was 24 ± 11 against 266 foods. Compared to baseline, there was a statistically significant reduction in the number of headache days (from 10.5 ± 4.4 to 7.5 ± 3.7; P < 0.001) and number of migraine attacks (from 9.0 ± 4.4 to 6.2 ± 3.8; P < 0.001) in the elimination diet period. Conclusion: This is the first randomised, cross-over study in migraineurs, showing that diet restriction based on IgG antibodies is an effective strategy in reducing the frequency of migraine attacks.

Subacute sclerosing panencephalitis: clinical and magnetic resonance imaging evaluation of 36 patients.

We studied 36 patients (24 males, 12 females), all of whom had definite subacute sclerosing panencephalitis with typical periodic complexes in their electroencephalograms and increased titers of measles antibody in serum and cerebrospinal fluid. Their clinical and laboratory findings on admission were reviewed retrospectively. The age at onset of symptoms varied from 4 to 23 years. The average age at onset of disease was 13.1 ± 4.18 years. The mean of the duration from the infection to the onset of subacute sclerosing panencephalitis was 9 years. Unusual symptoms, especially in the early periods of disease, included hemiparesis (7 patients), headache (3), generalized tonic-clonic seizures (6), absence seizure (1), nausea (3), and vomiting (3). Twenty-six cranial magnetic resonance imaging (MRI) and 12 computed tomography examinations were performed. Nine patients had normal MRI. In the early stages, lesions usually involved parieto-occipital corticosubcortical regions asymmetrically. In time, symmetric periventricular white-matter changes became more prominent. In addition to the common clinical findings in cases of subacute sclerosing panencephalitis reported in the literature, there were some different clinical features of the disease. Eventually, we concluded that there seems to be no correlation between the clinical stages and either the duration from the onset of subacute sclerosing panencephalitis or the MRI findings. (J Child Neurol 2002;17:25-29).

Hot Water Epilepsy: Clinical and Electrophysiologic Findings Based on 21 Cases

Summary:  Purpose: Our aim is to outline the clinical and electroencephalographic (EEG) features of patients with hot water epilepsy (HWE), a rare and unique form of reflex epilepsy.

Myoclonic seizures subside in the fourth decade in juvenile myoclonic epilepsy

Objective: Our aim was to assess the long-term follow-up of juvenile myoclonic epilepsy (JME), with an emphasis on the course of the myoclonic seizures. Methods: We enrolled 48 patients with JME (29 F, 19 M; aged 39.9 ± 9.5 years) followed up for a mean of 19.6 ± 5.7 years. The remission for 5 years and relapses were evaluated for all seizure types and the changes in severity/frequency of myoclonia were systematically questioned. The clinical and EEG features, antiepileptic drug (AED) treatment regimen, and systemic and psychiatric comorbid diseases were evaluated. Results: We found a benign course in 66.6% whereas 16.7% had pseudo-resistance due to problems in treatment or lifestyle. The true-resistant course observed in the remaining 16.7% was significantly associated with psychiatric disorders and the presence of thyroid diseases. In 54.2% of the patients, myoclonia were in remission for a mean duration of 8.4 ± 7.7 years, after an average age of 32.9 ± 9.6. Of these patients, 6 were on a lower dose of AED in comparison to the dosage needed to control the seizures in the beginning, and 5 patients had stopped AED treatment. None of the latter 11 patients except one relapsed during the follow-up. Furthermore, 21 other patients (43.8%) described substantial alleviation after age 31.3 ± 8.4 in the severity of myoclonia. Conclusion: Although a great majority of the patients with juvenile myoclonic epilepsy had continuing seizures after a follow-up of 20 years, almost all had either 5-year remission or a substantial alleviation of the myoclonic seizures.

Periodic lateralized epileptiform discharges: association with seizures

The clinical features and EEGs of 45 consecutive patients (40 adults and 5 children) who had periodic lateralized epileptiform discharges (PLEDs) were reviewed to determine the relationship between seizures and PLEDs. Focal encephalitis and ischemic stroke were the most frequent underlying processes for adult patients. All of the children, but only six of the adults, had long-lasting cerebral disorders whereas the remaining adults had acute or subacute illness. There were 38 patients (84.4%) experiencing a seizure disorder. Twenty-six of them had their first seizure during their acute illness, as the pattern of PLED was encountered. Eight cases had status epilepticus, and seven of them had epilepsia partialis continua. Nineteen patients had a recent seizure in the day when PLEDs were observed but not during EEG recording; 12 patients had their seizures within 10 days before the observation of PLED. PLEDs were grouped into three categories with respect to their extensions: lateralized to one hemisphere (n = 22), localized in one region (n = 17) and being prominent over one side with contralateral spread (n = 6). The last group was found to be more closely associated with frequent seizures or status epilepticus than the other two groups. Our results showed that PLEDs were highly correlated with recent seizures in the majority of the patients. These EEG findings may be considered as a manifestation of an increased neuronal excitability caused by different etiologies; but not an ictal pattern.

Late-onset and Slow-progressing Lafora Disease in Four Siblings with EPM2B Mutation

Summary:  We report a family with four brothers affected by Lafora disease (LD). Mean age at onset was 19.5 years (range, 17–21). In all cases, the initial obvious symptoms were diffuse myoclonus and occasional generalized tonic–clonic seizures (GTCSs), followed by cognitive difficulties. Severity of myoclonus, seizure diaries, and neurologic and neuropsychological status were finally evaluated in March 2005. The duration of follow‐up was >10 years for three subjects. Daily living activities and social interaction were preserved in all cases and, overall, the progression of the disease was slow. Genetic study revealed the homozygous mutation D146N in the EPM2B gene. We suggest that this mutation may be associated with a less severe LD phenotype.

Recurrent absence status epilepticus: clinical and EEG characteristics

In order to outline the clinical and EEG characteristics of recurrent absence status epilepticus (ASE), eight cases with more than two attacks of ASE were studied. Their current ages were between 13 and 84 years, and five of the patients were women. There was a history of epilepsy in five of the patients before the first ASE episode. A varying degree of confusion was the main clinical symptom with associated mild motor signs like perioral, eyelid and generalised myoclonus, seen in one, two and four patients respectively. Two of the patients had juvenile myoclonic epilepsy. One patient had an atypical form of childhood absence epilepsy characterised by recurrent ASE attacks on awakening. There were two patients with phantom absences and late onset generalised convulsions, one patient with perioral myoclonia and absences, and finally two patients with eyelid myoclonia with absences, which are proposed syndromes. On the EEGs that revealed the diagnosis of ASE, there was a marked variability of the generalised multispike and wave discharges. The EEG findings appeared to be syndrome-related with some exceptions. IV Clonazepam lead to a dramatic improvement. Our study shows that the majority of recurrent ASE cases do not fit into the International syndrome classification.

Epileptic Seizures in Behçet Disease

Summary:  Purpose: To outline the clinical characteristics of seizures in our large series of Behçet disease (BD) patients with neurologic involvement.