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KCNQ5 encodes the voltage-gated potassium channel K V 7.5, a member of the K V 7 channel family, which conducts the M-current. This current is a potent regulator of neuronal excitability by regulating membrane potential in the subthreshold range of action potentials and mediating the medium and slow afterhyperpolarization. Recently, we have identified five loss-of-function variants in KCNQ5 in patients with genetic generalized epilepsy. Using the most severe dominant-negative variant (R359C), we set out to investigate pharmacological therapeutic intervention by K V 7 channel openers on channel function and neuronal firing. Retigabine and gabapentin increased R359C-derived M-current amplitudes in HEK cells expressing homomeric or heteromeric mutant K V 7.5 channels. Retigabine was most effective in restoring K+ currents. Ten μM retigabine was sufficient to reach the level of WT currents without retigabine, whereas 100 μM of gabapentin showed less than half of this effect and application of 50 μM ZnCl 2 only significantly increased M-current amplitude in heteromeric channels. Overexpression of K V 7.5-WT potently inhibited neuronal firing by increasing the M-current, whereas R359C overexpression had the opposite effect and additionally decreased the medium afterhyperpolarization current. Both aforementioned drugs and Zn2+ reversed the effect of R359C expression by reducing firing to nearly normal levels at high current injections. Our study shows that a dominant-negative variant with a complete loss-of-function in K V 7.5 leads to largely increased neuronal firing which may explain a neuronal hyperexcitability in patients. K V 7 channel openers, such as retigabine or gabapentin, could be treatment options for patients currently displaying pharmacoresistant epilepsy and carrying loss-of-function variants in KCNQ5. K V 7.5 dominant-negative-LOF variants reduce the M-current in transfected HEK cells and primary hippocampal neuronal cultures. Neuronal firing in cultured hippocampal neurons transfected with K V 7.5-LOF channels is increased likely through a decrease in the medium afterhyperpolarization current resulting in an increased seizure susceptibility in the patients. This effect was fully counteracted by the K V 7 channel activators retigabine (RTG) and gabapentin (GBP). [Display omitted] • K V 7.5-LOF expression increases neuronal firing by decreasing I M and thus I mAHP. • K V 7.5-WT overexpression decreases neuronal firing by increasing I M. • Both retigabine and gabapentin counteract the LOF effect. • Gabapentin has potential as personalized treatment for patients carrying K V 7.5-LOF missense variants. [ABSTRACT FROM AUTHOR]

The four voltage-gated sodium channels SCN1/2/3/8A have been associated with heterogeneous types of developmental disorders, each presenting with disease specific temporal and cell type specific gene expression. Using single-cell RNA sequencing transcriptomic data from humans and mice, we observe that SCN1A is predominantly expressed in inhibitory neurons. In contrast, SCN2/3/8A are profoundly expressed in excitatory neurons with SCN2/3A starting prenatally, followed by SCN1/8A neonatally. In contrast to previous observations from low resolution RNA screens, we observe that all four genes are expressed in both excitatory and inhibitory neurons, however, exhibit differential expression strength. These findings provide molecular evidence, at single-cell resolution, to support the hypothesis that the excitatory/inhibitory (E/I) neuronal expression ratios of sodium channels are important regulatory mechanisms underlying brain homeostasis and neurological diseases. Modulating the E/I expression balance within cell types of sodium channels could serve as a potential strategy to develop targeted treatment for Na V -associated neuronal developmental disorders. • Transcriptome assays reveal distribution of SCN expression at single-cell level. • SCNs are found in excitatory & inhibitory cells with different expression strength. • SCN expression ratios regulate underlying brain homeostasis and neuronal disease. [ABSTRACT FROM AUTHOR]

Next-generation sequencing has enhanced discovery of many disease-associated genes in previously unexplained epilepsies, mainly in developmental and epileptic encephalopathies and familial epilepsies. We now classify these disorders according to the underlying molecular pathways, which encompass a diverse array of cellular and sub-cellular compartments/signalling processes including voltage-gated ion-channel defects. With the aim to develop and increase the use of precision medicine therapies, understanding the pathogenic mechanisms and consequences of disease-causing variants has gained major relevance in clinical care. The super-family of voltage-gated potassium channels is the largest and most diverse family among the ion channels, encompassing approximately 80 genes. Key potassium channelopathies include those affecting the K V , K Ca and K ir families, a significant proportion of which have been implicated in neurological disease. As for other ion channel disorders, different pathogenic variants within any individual voltage-gated potassium channel gene tend to affect channel protein function differently, causing heterogeneous clinical phenotypes. The focus of this review is to summarise recent clinical developments regarding the key voltage-gated potassium (K V) family-related epilepsies, which now encompasses approximately 12 established disease-associated genes, from the KCNA -, KCNB -, KCNC -, KCND -, KCNV -, KCNQ - and KCNH -subfamilies. [ABSTRACT FROM AUTHOR]

Abstract Mutations in the KCNA2 gene, coding for the voltage-gated K+ channel K v 1.2, can cause developmental and epileptic encephalopathies. K v 1.2 channels play an important role in the repolarization phase of an action potential in nerve cells. Here, we reprogrammed human skin fibroblasts from a 13-year-old male patient with developmental and epileptic encephalopathy carrying a point mutation (c.982T>G, p.Leu328Val) in KCNA2 to human induced pluripotent stem cells (iPSCs) (HIHDNEi001-A). The cells maintained a normal karyotype and their pluripotency state was verified by the expression and staining of several pluripotency markers and capability to differentiate into all three germ layers. [ABSTRACT FROM AUTHOR]

As reliable biomarkers of disease activity are lacking, monitoring of therapeutic response in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) remains a challenge. We sought to determine whether nerve ultrasound and electrophysiology scoring could close this gap. In CIDP patients (fulfilling EFNS/PNS criteria), we performed high-resolution nerve ultrasound to determine ultrasound pattern sum scores (UPSS) and predominant echotexture nerve conduction study scores (NCSS) as well as Medical Research Council sum scores (MRCSS) and inflammatory neuropathy cause and treatment disability scores (INCAT) at baseline and after 12 months of standard treatment. We retrospectively correlated ultrasound morphology with nerve histology when available. 72/80 CIDP patients featured multifocal nerve enlargement, and 35/80 were therapy-naïve. At baseline, clinical scores correlated with NCSS (r2 = 0.397 and r2 = 0.443, p < 0.01), but not or hardly with UPSS (Medical Research Council sum scores MRCSS r2 = 0.013, p = 0.332; inflammatory neuropathy cause and treatment disability scores INCAT r2 = 0.053, p = 0.048). Longitudinal changes in clinical scores, however, correlated significantly with changes in both UPSS and NCSS (r2 = 0.272-0.414, p < 0.0001). Combining nerve/fascicle size with echointensity and histology at baseline, we noted 3 distinct classes: 1) hypoechoic enlargement, reflecting active inflammation and onion bulbs; 2) nerve enlargement with additional hyperechogenic fascicles/perifascicular tissue in > 50% of measured segments, possibly reflecting axonal degeneration; and 3) almost no enlargement, reflecting "burned-out" or "cured" disease without active inflammation. Clinical improvement after 12 months was best in patients with pattern 1 (up to 75% vs up to 43% in pattern 2/3, Fisher's exact test p < 0.05). Nerve ultrasound has additional value not only for diagnosis, but also for classification of disease state and may predict treatment response. [ABSTRACT FROM AUTHOR]

Purpose: Periodic discharges in EEG and a history of rapidly progressive dementia are known to be associated with sporadic Creutzfeld-Jakob Disease (sCJD). Doubts regarding this rare but fatal diagnosis can arise, when episodic symptoms (seizures, psychiatric features, speech disturbances) are present and the EEG shows epileptiform discharges within this periodicity. This scenario may indicate non-convulsive status epilepticus (NCSE), which is - in contrast to sCJD - a treatable and frequent condition.Methods: Herein we report a small retrospective study of 4 elderly patients, who suffered from sCJD, but due to episodic symptoms and benzodiazepine-responsive epileptiform discharges in combination to a subacute cognitive decline, NCSE was considered as a potential differential diagnosis and therefore treated aggressively.Results: Ultimately, this treatment was not successful and sCJD was diagnosed in all cases. Hence, there was no diagnostic and prognostic value of abolishing periodic discharges in EEG via benzodiazepines in differentiating sCJD from NCSE in our series.Conclusion: These findings indicate that periodic discharges in sCJD can be responsive to benzodiazepines andnot necessarily help to differentiate differentiation between sCJD and NCSE of other causes. We argue that an aggressive anticonvulsive treatment in this scenario should be considered cautiously, especially for invasive options like general anesthesia. [ABSTRACT FROM AUTHOR]

Purpose To assess efficacy/tolerability of ezogabine (EZG)/retigabine (RTG) in combination with specified monotherapy antiepileptic drug (AED) treatments in adults with uncontrolled partial-onset seizures using a flexible dosing regimen. Methods NCT01227902 was an open-label, uncontrolled study of flexibly dosed EZG/RTG. Adults with partial-onset seizures must have been taking either carbamazepine/oxcarbazepine (CBZ/OXC), lamotrigine (LTG), levetiracetam (LEV), or valproic acid (VPA). The study comprised a screening/baseline phase, a 4-week titration phase (initiation on 150 mg/day [50 mg three times daily (TID)] with weekly increases of 150 mg/day [50 mg TID] over 4 weeks to 600 mg/day), and a flexible dose evaluation (FDE) phase (optional weekly dose changes of 50–150 mg/day, to an optimal daily dosage [300–1200 mg/day]). The primary efficacy endpoint was percentage of patients experiencing a ≥50% reduction from baseline in partial seizure frequency (responder rate) during the treatment phase (titration and FDE phases). Safety and tolerability were also assessed. Results Patients ( N = 203) were enrolled and received ≥1 dose of EZG/RTG. The dose of EZG/RTG prescribed most frequently during the treatment phase was 600 mg/day for all AED groups. Responder rates during the treatment phase were: 40.0% (CBZ/OXC), 32.0% (LTG), 50.0% (LEV), and 56.9% (VPA). Treatment-emergent adverse events occurred in 82% (CBZ/OXC), 76% (LTG), 73% (LEV), and 67% (VPA) of patients; most were of mild-to-moderate intensity. Conclusions EZG/RTG was effective as adjunctive therapy to CBZ/OXC, LTG, LEV, and VPA, using a flexible dosing regimen, in adults with partial-onset seizures; safety and tolerability were consistent with that previously observed. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: The group of the rare progressive myoclonic epilepsies (PME) include a wide spectrum of mitochondrial and metabolic diseases. In juvenile and adult ages, MERRF (myoclonic epilepsy with ragged red fibres) is the most common form. The underlying genetic defect in most patients with the syndrome of MERRF is a mutation in the tRNALys gene, but mutations were also detected in the tRNAPhe gene. Method: Here, we describe a 40 year old patient with prominent myoclonic seizures since 39 years of age without a mutation in the known genes who underwent intensive clinical, genetic and functional workup. Results: The patient had a slight mental retardation and a severe progressive hearing loss based on a defect of the inner ear on both sides. Ictal electroencephalography (EEG) showed bilateral occipital and generalized spikes and polyspikes induced and aggravated by photostimulation. A cranial magnetic resonance imaging (cMRI) detected a global cortical atrophy of the brain and mild periventricular white matter lesions. The electromyography (EMG) was normal but the muscle biopsy showed abundant ragged red fibres. Sequencing of the mitochondrial DNA from the skeletal muscle biopsy revealed a novel heteroplasmic mutation (m.4279A>G) in the tRNAIle gene which was functionally relevant as tested in single skeletal muscle fibre investigations. Conclusion: Mutations in tRNAIle were described in patients with chronic progressive external ophthalmoplegia (CPEO), prominent deafness or cardiomyopathy but, up to now, not in patients with myoclonic epilepsy. The degree of heteroplasmy of this novel mitochondrial DNA mutation was 70% in skeletal muscle but only 15% in blood, pointing to the diagnostic importance of a skeletal muscle biopsy also in patients with myoclonic epilepsy. [Copyright &y& Elsevier]

• First evidence that quantum sensors (optically pumped magnetometer OPM), can non-invasively detect fasciculations in neuromuscular patients. • Proposal of the necessary technical solutions to detect other forms of pathological spontaneous activity. • Introduction of magnetomyography as a new clinical neurophysiological diagnostic tool. This proof-of-principle-study evaluated the extent to which spontaneous activity (SA) of the muscle can be detected via non-invasive magnetomyography (MMG) with optically pumped magnetometers (OPM). Five patients, who together exhibited all forms of SA (fibrillations, positive sharp waves, fasciculations, myotonic discharges, complex-repetitive discharges) with conventional needle electromyography (EMG), were studied by OPM-MMG and simultaneous surface EMG (sEMG) while at rest, during light muscle activation, and when a muscle stretch reflex was elicited. Three healthy subjects were measured as controls. SA was considered apparent in the OPM-MMG if a signal could be visually detected that corresponded in shape and frequency to the SA in the respective needle EMG. SA in the context of fasciculations could be detected in 2 of 5 patients by simultaneous OPM-MMG/sEMG. Other forms of SA could not be detected at rest, during light muscle activation, or after provocation of a muscle stretch reflex. Results show that fasciculations could be detected non-invasively via a new method (OPM). We show that other forms of SA are not detectable with current OPM and propose necessary technical solutions to overcome this circumstance. Our results motivate to pursue OPM-MMG as a new clinical neurophysiological diagnostic. [ABSTRACT FROM AUTHOR]

Increased oxidative stress has been widely implicated in the pathogenesis in various forms of human epilepsy. Here, we report a homozygous mutation in TXNRD1 (thioredoxin reductase 1) in a family with genetic generalized epilepsy. TXNRD1 is an essential selenium-containing enzyme involved in detoxification of reactive oxygen species (ROS) and redox signaling. The TXNRD1 mutation p.Pro190Leu affecting a highly conserved amino acid residue was identified by whole-exome sequencing of blood DNA from the index patient. The detected mutation and its segregation within the family – all siblings of the index patient were homozygous and the parents heterozygous – were confirmed by Sanger sequencing. TXNRD1 activity was determined in subcellular fractions from a skeletal muscle biopsy and skin fibroblasts of the index patient and the expression levels of the mutated protein were assessed by 75 Se labeling and Western blot analysis. As result of the mutation, the activity of TXNRD1 was reduced in the patient's fibroblasts and skeletal muscle (to 34±3% and 16±8% of controls, respectively). In fibroblasts, we detected reduced 75 Se-labeling of the enzyme (41±3% of controls). An in-depth in vitro kinetic analysis of the recombinant mutated TXNRD1 indicated 30–40% lowered k cat /Se values. Therefore, a reduced activity of the enzyme in the patient's tissue samples is explained by (i) lower enzyme turnover and (ii) reduced abundance of the mutated enzyme as confirmed by Western blotting and 75 Se labeling. The mutant fibroblasts were also found to be less resistant to a hydrogen peroxide challenge. Our data agree with a potential role of insufficient ROS detoxification for disease manifestation in genetic generalized epilepsy. [ABSTRACT FROM AUTHOR]

Abstract: Crototropone (3-hydroxy-5,6-dimethoxy-2-methylcyclohepta-2,4,6-trien-1-one) was isolated from roots of Croton zehntneri. The structure was established by spectroscopic methods. [Copyright &y& Elsevier]

Summary: Background: Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in people with chronic refractory epilepsy. Very rarely, SUDEP occurs in epilepsy monitoring units, providing highly informative data for its still elusive pathophysiology. The MORTEMUS study expanded these data through comprehensive evaluation of cardiorespiratory arrests encountered in epilepsy monitoring units worldwide. Methods: Between Jan 1, 2008, and Dec 29, 2009, we did a systematic retrospective survey of epilepsy monitoring units located in Europe, Israel, Australia, and New Zealand, to retrieve data for all cardiorespiratory arrests recorded in these units and estimate their incidence. Epilepsy monitoring units from other regions were invited to report similar cases to further explore the mechanisms. An expert panel reviewed data, including video electroencephalogram (VEEG) and electrocardiogram material at the time of cardiorespiratory arrests whenever available. Findings: 147 (92%) of 160 units responded to the survey. 29 cardiorespiratory arrests, including 16 SUDEP (14 at night), nine near SUDEP, and four deaths from other causes, were reported. Cardiorespiratory data, available for ten cases of SUDEP, showed a consistent and previously unrecognised pattern whereby rapid breathing (18–50 breaths per min) developed after secondary generalised tonic-clonic seizure, followed within 3 min by transient or terminal cardiorespiratory dysfunction. Where transient, this dysfunction later recurred with terminal apnoea occurring within 11 min of the end of the seizure, followed by cardiac arrest. SUDEP incidence in adult epilepsy monitoring units was 5·1 (95% CI 2·6–9·2) per 1000 patient-years, with a risk of 1·2 (0·6–2·1) per 10 000 VEEG monitorings, probably aggravated by suboptimum supervision and possibly by antiepileptic drug withdrawal. Interpretation: SUDEP in epilepsy monitoring units primarily follows an early postictal, centrally mediated, severe alteration of respiratory and cardiac function induced by generalised tonic-clonic seizure, leading to immediate death or a short period of partly restored cardiorespiratory function followed by terminal apnoea then cardiac arrest. Improved supervision is warranted in epilepsy monitoring units, in particular during night time. Funding: Commission of European Affairs of the International League Against Epilepsy. [Copyright &y& Elsevier]

Summary: Background: GRM4 encoding the group III metabotropic glutamate receptor 4 (mGluR4), is located on the chromosomal segment 6p21.3 where tentative susceptibility loci for Juvenile Myoclonic Epilepsy (JME) and Photoparoxysmal Response (PPR) have been mapped. The present candidate gene study examined if variation in GRM4 confers susceptibility to IGE. Patients and methods: The case-control association sample included 564 unrelated IGE patients and 733 population controls of German descent. Association analysis was carried out for 17 single nucleotide polymorphisms (SNPs) covering the genomic GRM4 sequence for all IGE patients as well as for two common IGE subsyndromes [Juvenile Myoclonic Epilepsy (JME, n =215) and Childhood Absence Epilepsy (CAE, n =175)]. Sequence analysis was performed in 85 IGE and 42 PPR cases and 44 controls. Results: Nominally significant asssociations were detected between IGE and seven GRM4 SNPs (with P-values ranging from 0.037 to 0.0036), between JME and five SNPs (P =0.042–0.0106), and between CAE and two SNPs (P =0.0466–0.0021). Four novel SNPs were identified by sequence analysis. Conclusions: Our association findings support the hypothesis that GRM4 sequence variants might confer low-risk effects to the etiology of IGE. A minor pathogenetic contribution of the examined variants is possible. These exploratory findings warrant further replication analyses. [Copyright &y& Elsevier]

Abstract: KCNQ-type potassium channels generate the so-called M-current regulating excitability in many neurons. Mutations in KCNQ2/KCNQ3 channels can cause benign familial neonatal convulsions (BFNC). We describe the immunohistochemical staining of adult and developing mouse brain using an antibody directed against the N-terminus of KCNQ3 channels (KCNQ3N). A widespread KCNQ3N immunoreactivity predominantly of neuropil but also of somata was detected in different regions of the adult mouse brain, in particular in the hippocampus, cortex, thalamus and cerebellum. This staining pattern appeared gradually and became more intense during development. In the pyramidal cell layer of the hippocampus, the immunoreactivity changed from a more somatic to a neuropil staining during development. These changes during maturation might be related to the age-dependent phenotype of BFNC. [Copyright &y& Elsevier]

Abstract: The syndrome of benign familial neonatal convulsions (BFNC) is characterized by seizures starting within the first days of life and disappearing within weeks to months. BFNC is caused by loss-of-function mutations in the potassium channels KCNQ2 and KCNQ3 which can well explain the resulting neuronal hyperexcitability. However, it is not understood why seizures predominantly occur in the neonatal period. A potential explanation might be a change in the expression pattern of these channels during development. We therefore performed an immunohistochemical analysis of mouse brain slices at different stages of postnatal development using an antibody recognizing the C-terminus of the KCNQ2 channel. A widespread immunohistochemical staining was observed, particularly in the hippocampus, caudoputamen, globus pallidus, cortex, thalamus, hypothalamus and midbrain. In the adult mouse brain, a predominantly axonal staining pattern was found, most observed in the caudoputamen, the alveus and the mossy fiber pathway of the hippocampus. The hippocampal staining pattern of adult mice was not observed before P8 and gradually developed between P11 and P21. Differences in the distribution of KCNQ2 channels within neurons between the neonatal period and adult stages might contribute to the increased seizure susceptibility in BFNC in humans. [Copyright &y& Elsevier]

Myotonic dystrophy (DM1) and proximal myotonic myopathy (PROMM or DM2) are two distinct muscular disorders with multisystemic involvement. Both have previously been reported to be associated with cognitive impairment and white matter lesions detected by cerebral magnetic resonance imaging (MRI). In this study, the extent of brain atrophy was investigated in vivo in ten DM1 and nine PROMM patients in comparison to age-matched healthy controls for each group. The diagnosis was confirmed by DNA analysis of all patients. As a quantitative marker, the ratio of brain parenchymal to intracranial volume, called brain parenchymal fraction (BPF), was calculated from 3-dimensional MRI data using an automated analysis technique. Compared to age-matched healthy controls (mean BPF 0.852±0.032), the BPF in DM1 patients (0.713±0.031) was highly significantly decreased (P<0.001). In contrast, the PROMM patients (mean BPF 0.792±0.029) showed only slightly decreased BPF values (P<0.05). BPF was not significantly correlated to any of the clinical or genetic parameters in both diseases (disease duration, motor score, educational level, and number of CTG repeats in the expanded allele). In summary, global brain atrophy was demonstrated to occur in both diseases, but was more severely manifestated in DM1 patients. [Copyright &y& Elsevier]

Abstract: Background: Sporadic and familial hemiplegic migraines are rare paroxysmal disorders characterized by transient hemiparesis and headache. The distinction is based on whether other family members are affected. In 50% of cases, these migraines are caused by CACNA1 A missense mutations. Patients: We describe a boy with a particularly severe phenotype and a de novo R1349Q mutation of the CACNA1 A gene. Results: The patient suffered from early-onset profound mental retardation, epileptic seizures, cerebellar ataxia, and progressive cerebellar atrophy. He experienced prolonged attacks of migraine with hemiparesis, seizures, altered consciousness, and fever resulting from minor head traumas. A prolonged hemiplegic attack improved following a 5-day treatment of 100 mg/d methylprednisolone. Conclusion: R1349Q mutation of the CACN1 A gene may be associated with a severe phenotype. Corticoids might be beneficial in prolonged hemiplegic attacks. [Copyright &y& Elsevier]