Epilepsy Research UK (ERUK) Fellow Awarded Prestigious MRC Grant To Investigate Dravet Syndrome

2017 ERUK Fellow Dr Gabriele Lignani, has been awarded a New Investigator Research Grant, worth nearly £700,000 by the Medical Research Council (MRC), to investigate the potential use of gene therapy in Dravet syndrome. This research project will build on Dr Lignani’s ongoing fellowship research – GeneLoop, which is currently investigating the potential of gene therapy as a treatment for acquired intractable epilepsy.

Dravet Syndrome is a severe and extremely rare but catastrophic neurological disorder affecting young children (approximately 1 in 19,000 people). Every day 3 or 4 children are diagnosed with Dravet syndrome worldwide, with symptoms including epilepsy, autism, movement disorders, and sleep disturbances. To date, the majority of therapies are ineffective or poorly tolerated. Sodium channel drugs, which are some of the most commonly prescribed and effective antiepileptic drugs may even worsen Dravet syndrome.

Dr Lignani said: “This research will be useful not only to understand if a permanent general treatment for Dravet syndrome is achievable, but will also give insight into the potential of the techniques to cure other neurological conditions caused by similar mutations in different genes.”

He continued “This research will be useful not only to understand if a permanent general treatment for Dravet syndrome is achievable, but will also give insight into the potential of the techniques to cure other neurological conditions caused by similar mutations in different genes.”

Dr Lignani’s ERUK Fellowship officially began in 2018 but is already showing promising results. His team’s work thus far has focused on developing and testing their gene therapy tools, and they have found that this tool is able to subdue neurons during epileptic activity. The following stages of the fellowship will involve trialing these tools in models of acquired intractable epilepsy.

Use of Next-Generation Sequencing Panel as First-Tier in Diagnostic Process May Enable Precision Medicine

Objective: Molecular genetic etiologies in epilepsy have become better understood in recent years, creating important opportunities for precision medicine. Building on these advances, detailed studies of the complexities and outcomes of genetic testing for epilepsy can provide useful insights that inform and refine diagnostic approaches and illuminate the potential for precision medicine in epilepsy.

Methods: Researchers used a multi-gene next-generation sequencing (NGS) panel with simultaneous sequence and exonic copy number variant detection to investigate up to 183 epilepsy-related genes in 9,769 individuals. Clinical variant interpretation was performed using a semi-quantitative scoring system based on existing professional practice guidelines.

Results: Molecular genetic testing provided a diagnosis in 14.9-24.4% of individuals with epilepsy, depending on the NGS panel used. More than half of these diagnoses were in children younger than 5 years. Notably, the testing had possible precision medicine implications in 33% of individuals who received definitive diagnostic results. Only 30 genes provided 80% of molecular diagnoses. While most clinically significant findings were single-nucleotide variants, ~15% were other types that are often challenging to detect with traditional methods. In addition to clinically significant variants, there were many others that initially had uncertain significance; reclassification of 1612 such variants with parental testing or other evidence contributed to 18.5% of diagnostic results overall and 6.1% of results with precision medicine implications.

Significance: Using a next-generation sequencing panel with key high-yield genes and robust analytic sensitivity as a first-tier test early in the diagnostic process, especially for children younger than 5 years, can possibly enable precision medicine approaches in a significant number of individuals with epilepsy.

Encoded Therapeutics Bags $104M to Propel ‘Precision Gene Therapy’ for Dravet Syndrome

Encoded Therapeutics reeled in $104 million in series C cash to bankroll the development of its lead program: a precision gene therapy for Dravet syndrome, a rare form of epilepsy. The Bay Area biotech will also use the funds to push its preclinical programs and come up with new treatments for severe genetic disorders.

The company’s work is based on a platform designed to overcome hurdles it has identified in the gene therapy space. Gene therapies tend to work in one of three ways: They deliver a healthy copy of a faulty gene, introduce a new gene into the body or “knock out” a defective gene. But they can run into problems with cell selectivity, potency and the ability to control endogenous genes, Encoded CEO Karthik Ramamoorthi, Ph.D., told FierceBiotech.

“We’ve developed a series of technologies that are both computational and genomics- or sequencing-based that allow us to screen for and identify sequences in vivo that control where and when genes are able to be expressed,” Ramamoorthi said. “We take these sequences and place them in gene therapies—such as adeno-associated viruses (AAVs)—that allow us to control where the adeno-associated viruses are able to express the payload.”

Clinical Evolution and Epilepsy Outcome in Three Patients with CDKL5-Related Developmental Encephalopathy

Objective: To further characterize CDKL5-related disorder, previously classified as an early-onset seizure variant of Rett syndrome, which is currently considered a specific and independent early-infantile epileptic encephalopathy.

Results: Researchers describe the epileptic phenotype and neurocognitive development in three girls with CDKL5 mutations showing severe neurodevelopmental impairment, with different epileptic phenotypes and severity. The patients differed regarding age at epilepsy onset, seizure frequency, duration of “honeymoon periods”, as well as EEG features. The “honeymoon period”, defined as a seizure-free period longer than two months, represented, in this case series, a good indicator of the epilepsy outcome, but not of the severity of developmental impairment. However, even during the “honeymoon period”, the interictal EEG showed epileptiform abnormalities, slowing, or a disappearance of physiological pattern. The natural history of CDKL5 disorder was compared between the three girls, focusing on the relationship between electroclinical features and neurological development.

Significance: These findings suggest that CDKL5 mutations likely play a direct role in psychomotor development, whereas epilepsy is one of the clinical features associated with this complex disorder.

Epilepsy Research Findings: June 2019

This month’s round-up of epilepsy news features an announcement about a new antiepileptic rescue medication, NAYZILAM®. This therapy is the first FDA-approved nasal treatment option for people with epilepsy who experience episodes of frequent seizure activity.

We also highlight many research advances, from the discovery of a compound found in fruit and honey which can inhibit seizures to the development of a new drug to treat Dravet syndrome. Research in the cannabidiol (CBD) space has also advanced, with the creation of a synthetic form of CBD which may be easier to purify and does not need to be cultivated from hemp plants.

In more sobering news, reports over the past month show that one-third of epilepsy cases go without appropriate treatment for up to three years following diagnosis. In addition, people with psychogenic nonepileptic seizures (PNES) as well as epileptic seizures may be at a higher risk for sudden unexpected death in epilepsy (SUDEP)during the years immediately following diagnosis with PNES.

Summaries of all highlighted studies follow below. I’ve organized the findings into three categories: Treatment Advances, Research Discoveries, and Also Notable.

Treatment Advances

FDA Approves NAYZILAM® Nasal Spray to Treat Intermittent, Stereotypic Episodes of Frequent Seizure Activity in People Living with Epilepsy in the US
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The FDA has approved a New Drug Application for UCB’s newest antiepileptic drug NAYZILAM® (midazolam) nasal spray. This therapy is a benzodiazepine indicated for the acute treatment of intermittent, stereotypic episodes of frequent seizure activity (i.e., seizure clusters, acute repetitive seizures) distinct from a patient’s usual seizure pattern in individuals with epilepsy who are 12 years of age and older.

Study Advances More Effective Laser Ablation and Standard Epilepsy Surgery 
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In the largest study of its kind to date, researchers across 11 centers analyzed data on a relatively new minimally invasive alternative surgery for epilepsy. These researchers discovered changes that could make the procedure more effective in both laser ablation and standard surgery.

Research Discoveries

Brain Network Activity can Improve in Epilepsy Patients after Surgery
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Successful epilepsy surgery can improve brain connectivity similar to patterns seen in people without epilepsy, according to a new study published in the journal Neurosurgery. The study of 15 people with temporal lobe epilepsy is the first to show improvements in brain networks after surgery compared to a group of healthy subjects.

New Drug Could Help Treat Neonatal Seizures
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A new drug that inhibits neonatal seizures in rodent models could open new avenues for epilepsy treatment in human newborns. Researchers have found that gluconate—a small organic compound found in fruit and honey—acts as an anticonvulsant, inhibiting seizures by targeting the activity of channels that control the flow of chloride ions in and out of neonatal neurons.

Research Looks to Halt Stress-Induced Seizures Following Brain Injury
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The likelihood of developing epilepsy increases significantly with a traumatic brain injury. Stress and anxiety increase that likelihood even more dramatically. Researchers have been able to demonstrate that an injured brain responds differently to stress hormones than a healthy brain. The research team showed abnormal electrical activity in the brain tied to these stress-induced seizures and, most importantly, found a way to stop this activity from occurring.

Synthetic Version of Cannabidiol (CBD) Treats Seizures in Rats
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A synthetic, non-intoxicating analogue of CBD was found to be effective for treating seizures in rats. Researchers note the synthetic CBD alternative is easier to purify than a plant extract, eliminates the need to use agricultural land for hemp cultivation, and could avoid legal complications associated with cannabis-related products.

AZD7325 Has Seizure-Protective Effect in Mouse Model of Dravet Syndrome, Study Says
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Treatment with AZD7325, a compound that stimulates an inhibitory receptor in the brain, has a seizure-protective effect in a mouse model of Dravet syndrome. This treatment significantly increased the temperature threshold animals could withstand without experiencing any seizures during a hyperthermia-induced seizure test.

Children’s Brains Reorganize after Epilepsy Surgery to Retain Visual Perception
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Children can keep their full ability to process and understand visual information after brain surgery for severe epilepsy, according to a study funded by the National Eye Institute, part of the National Institutes of Health. This new report from a study of children who underwent epilepsy surgery and suggests that the lasting effects on visual perception can be minimal, even among children who lost tissue in the brain’s visual centers.

One-Third of Epilepsy Cases Go Untreated up to 3 Years After Diagnosis
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A small yet substantial subset of patients with newly diagnosed epilepsy go without appropriate treatment approximately 3 years after diagnosis. This gap in treatment may be increasing the risk for medical events and hospitalization in these patients.

Study Suggests ‘High Risk Period’ for SUDEP for People with Psychogenic Nonepileptic Seizures in Addition to Epileptic Seizures 
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Findings of a recently published study suggest that patients with comorbid epileptic seizures (ES) and Psychogenic Nonepileptic Seizures (PNES) can die from SUDEP and that there may be a high?risk period after the diagnosis of PNES is made. The authors state such patients should be closely monitored and provided with coordinated care of both their epilepsy and psychiatric disorder(s).

Also Notable

Fralin Biomedical Research Institute Neuroscientist Awarded Grant to Study Epilepsy
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Featuring CURE Grantee Dr. Sharon Swanger

Dr. Sharon Swanger of the Fralin Biomedical Research Institute was recently awarded a $1.7 million grant through the National Institute of Neurological Disorders and Stroke to study the role of glutamate receptors in the thalamus – an area of the brain involved in seizure generation. “If we can figure out how each [receptor] subtype functions and modulate select subtypes, then maybe we can target therapies to the circuit where the disease originated while leaving healthy circuits intact,” said Dr. Swanger.

Tool Helps GPs Predict Risk of Seizures in Pregnancy
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Doctors, midwives, and others can use a new risk calculator to identify those pregnant women at high-risk of seizures and to plan early referral for specialist input. The specialist could determine the need for close monitoring in pregnancy, labor, and after birth, and assess antiepileptic drug management, according to new research in PLOS Medicine. The study authors added that the model’s performance is unlikely to vary with the antiepilepsy drug dose management strategy – and that it could save maternal and infant lives.

Development of Epilepsy Prediction Device to Improve Independence for People with Epilepsy
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The University of Sydney’s Faculty of Engineering and Information Technologies is developing a system, NeuroSyd, which aims at real-time monitoring and processing of brain-signals while driving in a group of people living with epilepsy. NeuroSyd will be developed to deliver an early warning of the likelihood of an epileptic seizure.

Pfizer’s Lyrica at Doses 5mg and 10mg Fails Phase 3 Trial in Epilepsy
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Pfizer’s Lyrica has failed to meet its primary endpoint in a phase 3 trial in primary generalized tonic-clonic (PGTC) seizures. The study evaluated two doses of the drug – 5 mg and 10 mg – over a period of 12 weeks. Treatment with the drug did not result in a statistically significant reduction in seizure frequency versus placebo. Another phase 3 trial in May 2018 was successful, showing that a 14 mg dose of Lyrica resulted in a statistically significant reduction in seizure frequency versus placebo.

Advancing Science for Children with Epilepsy and Movement Disorders

Two Michigan State University College of Osteopathic Medicine graduate students are advancing the science behind genetic mutations that cause rare forms of epilepsy and movement disorders.

Huijie Feng, a doctoral student in the Department of Pharmacology and Toxicology, and Casandra Larrivee, a master’s student in the comparative medicine and integrative biology program, have found that different mutations in the GNAO1 gene in mice correlate to different characteristics, or phenotypes, of movement disorders in humans.

The findings are published in PLoS ONE.

The work adds to research started in 2013 by Richard Neubig, professor and chair of MSU’s pharmacology and toxicology department, whose focus at that time was on cardiovascular disease.

While using mice with a GNAO1 protein mutation, one unexpectedly had a seizure. This begged the question of whether the mutation could be linked to a seizure disorder.

Further investigation indicated that these mice were prone to seizures and soon after, four children who earlier had been diagnosed with Early Infantile Epileptic Encephalopathy, or EIEE, were also found to have the same mutations.

CURE Discovery: New Genetic Models of Epileptic Encephalopathies Deepen Our Understanding

This research is generously supported by a grant from Jen Scott and Pierre-Gilles Henry, PhD, in honor of Felix Henry.

Key Points

  • CURE grantee Dr. Mingshan Xue created mice modeling the features of STXBP1-related epileptic encephalopathy (EE) to explore why not having enough STXBP1 activity can cause epilepsy.
  • The team found that inhibitory brain signaling was diminished in the models, causing excessive neuronal excitation, seizures, and other neurological features seen in humans with EE.
  • The long-term goal of the team’s project is to understand the mechanisms that cause EEs and use this knowledge to develop new therapies.

Deep Dive

Reduced activity of a gene called STXBP1 is one of the most common causes of epileptic encephalopathy (EE),1a group of severe pediatric epilepsies which includes Ohtahara Syndrome, West Syndrome, and Dravet Syndrome. Patients with EE often have aggressive, treatment-resistant seizures, developmental delays, behavioral deficits, and intellectual disability among other clinical features. There is an urgent need to better understand these syndromes and develop new therapies for them.

CURE grantee Dr. Mingshan Xue and his colleagues at the Baylor College of Medicine created mouse models with reduced STXBP1 activity to study epilepsy associated with this genetic variant. Through extensive testing, they determined these mice accurately represented EE clinical features such as seizures, behavioral, and cognitive deficits.2

For their CURE-funded work, the team used these models to determine how not having enough STXBP1 activity could cause EE. The team previously observed high levels of neuronal excitation in the brains of mice with low STXBP1. Thus, Dr. Xue’s team hypothesized that not having enough STXBP1 must prevent inhibitory neuronal signaling, causing an imbalance between excitation and inhibition in the brain.

To test this, the team recorded the electrical activity of neurons in the model with reduced STXBP1 activity. They found that inhibitory brain signaling was indeed diminished in these mice while excitatory signaling was not affected, resulting in excessive excitation, seizures, and other neurological features of EE. Further testing revealed that mice with reduced STXBP1 activity specifically in inhibitory neurons had higher anxiety, impaired motor skills, and reduced cognitive function – all features that are seen in humans with EE.

EEs are typically hard to treat with currently available options. The team’s long-term goal is to understand the mechanisms that cause EEs and use this knowledge to develop new therapies. Since completing their CURE-funded grant, Dr. Xue and his co-investigator have received a National Institutes of Health grant, as well as an American Epilepsy Society postdoctoral fellowship to continue this important work.

Bridging the Gap Between STXBP1 Researchers and Families

We are honored to sponsor and attend the first ever STXBP1 Investigators and Family Meeting (SIFM) on June 21, 2019 and June 22, 2019 in Philadelphia. This conference is hosted by STXBP1 Foundation and the Center for Cellular and Molecular Therapeutics (CCMT).

The need for developing community and driving more research on this group of EEs is clear. The inaugural SIFM will bring together researchers and families of individuals with STXBP1 encephalopathies to foster community development and accelerate the search for a cure. This conference is designed to encourage interaction and in-depth discussions among researchers and clinicians to further research and innovation in this field.

You can find out more information about this conference here.

1 Carvill GL et.al. Nat Genet. 2013 Jul;45(7):825-30. doi: 10.1038/ng.2646
2 Wu Chen et.al., Apr 29, 2019, https://www.biorxiv.org/content/10.1101/621516v1

Clinical Study Finds Two Types of SCN8A-Related Epilepsy: Slowly Emerging or Sudden Onset of Epilepsy

Objective: To describe the mode of onset of SCN8A-related severe epilepsy in order to facilitate early recognition, and eventually early treatment with sodium channel blockers.

Methods: Researchers reviewed the phenotype of patients carrying a mutation in the SCN8A gene, among a multicentric cohort of 638 patients prospectively followed by several pediatric neurologists. The study focused on the way clinicians made the diagnosis of epileptic encephalopathy, the very first symptoms, electroencephalography (EEG) findings, and seizure types. The team made genotypic/phenotypic correlation based on epilepsy-associated missense variant localization over the protein.

Results: The study found 19 patients carrying a de novo mutation of SCN8A, representing 3% of our cohort, with 9 mutations being novel. Age at onset of epilepsy was 1 day to 16 months. The team also found two modes of onset: 12 patients had slowly emerging onset with rare and/or subtle seizures and normal interictal EEG (group 1). The first event was either acute generalized tonic-clonic seizure (GTCS; Group  1a, n = 6) or episodes of myoclonic jerks that were often mistaken for sleep-related movements or other movement disorders (Group 1b, n = 6). Seven patients had a sudden onset of frequent tonic seizures or epileptic spasms with abnormal interictal EEG leading to rapid diagnosis of epileptic encephalopathy. Sodium channel blockers were effective or nonaggravating in most cases.

Significance: SCN8A is the third most prevalent early onset epileptic encephalopathy gene and is associated with two modes of onset of epilepsy.

Epilepsy Research Findings: May 2019

In this month’s research news, treatments, genetic analysis, and preclinical work offer hope to those impacted by hard-to-treat or difficult-to-diagnose forms of epilepsy.

Exciting treatment developments include a positive Phase 3 clinical trial outcomefor the cannabidiol-based drug EPIDIOLEX® for the treatment of seizures associated with tuberous sclerosis complex. In addition, an improved treatment regimen targeting the severe, prolonged seizures that make up status epilepticus has been created.

In promising genetics news, a report from CURE’s own Epilepsy Genetics Initiativeunderscores the value of continued reanalysis of genetic information from people with epilepsy to increase their chances of obtaining a genetic diagnosis for their epilepsy.

Additionally, important preclinical work led by CURE Grantees Dr. Chris Dulla and Dr. Janice Naegele uncovers a potential drug to treat post-traumatic epilepsy and a way to restore the balance of brain activity and reduce seizures in temporal lobe epilepsy, respectively.

Summaries of all highlighted studies follow below. I’ve organized the findings into four categories: Treatment Advances, Diagnostic Advances, Research Discoveries, and Also Notable.

Treatment Advances

GW Pharmaceuticals Reports Reduction in Seizure Frequency for EPIDIOLEX® (cannabidiol) Oral Solution in Patients with Seizures Associated With Tuberous Sclerosis Complex
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GW Pharmaceuticals and Greenwich Biosciences announced positive top-line results of a Phase 3 clinical trial of EPIDIOLEX® (cannabidiol or CBD) in the treatment of seizures associated with Tuberous Sclerosis Complex (TSC). TSC is a rare and severe form of childhood-onset epilepsy. In this trial, EPIDIOLEX met its primary endpoint, which was a reduction in seizure frequency in the group given EPIDIOLEX compared to the placebo group.

Breakthrough for Children with Serious Epileptic Seizures
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A new treatment regimen of administering levetiracetam and phenytoin one after the other has given emergency medicine doctors a better way to treat severe, prolonged epileptic seizures in children. These treatment modifications will lower the chances of intubation and intensive care, as well as increase the chances of children recovering more quickly.

Diagnostic Advances

The Epilepsy Genetics Initiative: Systematic Reanalysis of Diagnostic Exomes Increases Yield
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Featuring CURE’s Epilepsy Genetics Initiative

Results from CURE’s Epilepsy Genetics Initiative (EGI) show that when the genetic information of a person with epilepsy is systematically reanalyzed, there is an increase in the return of a genetic diagnosis. Eight new diagnoses were made as a result of updated annotations or the discovery of novel epilepsy genes after the initial diagnostic analysis was performed. One novel epilepsy gene was discovered through dual interrogation of research and clinically generated whole-exome sequencing. According to this recently-published report, EGI’s contributions to gene discovery underscore the importance of data sharing and the value of collaborative enterprises.

Research Discoveries

Using a Drug that Mimics the Ketogenic Diet to Help Prevent Epilepsy after Traumatic Brain Injury
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Featuring the work of CURE Grantee Dr. Chris Dulla

Neuroscientists led by CURE Grantee Dr. Chris Dulla at Tufts University School of Medicine prevented the development of epileptic activity in mice after traumatic brain injury by using a drug that mimics the metabolic effects of the ketogenic diet.

Neural Stem Cell Transplantation May Reduce Abnormal Increases in New Cells in the Brains of Mice with Temporal Lobe Epilepsy
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Featuring the work of CURE Grantee Dr. Janice Naegele

According to a new, CURE-funded study featuring the work of grantee Dr. Janice Naegele, the transplantation of inhibitory cells into the brains of mice with temporal lobe epilepsy may reduce the abnormal growth of new neurons in an area of the brain called the hippocampus. This in turn could reduce brain hyperexcitability that leads to seizures.

Stimulating the Epileptic Brain Breaks Up Neural Networks to Prevent Seizures
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Responsive neurostimulation treats epilepsy by detecting seizures and intervening with a jolt of electric current. Over time, most patients find their seizures become fewer and further between. New evidence suggests responsive neurostimulation can remodel the brain to be less susceptible to seizures.

Scientists Discover Trigger Region for Absence Epileptic Seizures
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Scientists have discovered a neurological origin for absence seizures – a type of seizure characterized by very short periods of lost consciousness in which people appear to stare blankly at nothing. Using a mouse model of childhood epilepsy, a group of scientists has shown that absence epilepsy can be triggered by impaired communication between two brain regions: the cortex and the striatum.

Autism-Related Memory and Seizures Improved through Gene Repair in Adults
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Scientists have shown that correcting the protein deficiency caused by a genetic form of autism spectrum disorder in adult mice can improve behavioral and electrophysiological measures of both memory and seizure. The evidence suggests this is true even when the treatment is carried out well past what has traditionally been thought of as the critical window of early brain development.

Drug Used to Treat Multiple Sclerosis May Be Beneficial for Individuals with Epilepsy 
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A drug commonly used to treat multiple sclerosis may, after necessary modifications, one day be used to treat patients with epilepsy, according to research from the laboratory of Dr. Inna Slutsky.

Study Reveals How Glial Cells May Play Key Epilepsy Role
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A study provides potential new targets for treating epilepsy and novel fundamental insights into the relationship between neurons and their glial “helper” cells. This study reports finding a key sequence of molecular events in which the genetic mutation in a fruit fly model of epilepsy leaves neurons vulnerable to becoming hyper-activated by stress, leading to seizures.

Ketogenic Diet May Reduce Sudden Unexpected Deaths in Epilepsy, Mouse Study Suggests
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Sudden unexpected death in epilepsy (SUDEP) occurs more frequently during the early evening and is significantly prevented by prolonged use of the ketogenic diet, research in a mouse model of Dravet syndrome suggests. The reasons why this happens are unclear and should be examined in more depth by future studies, but these findings may be useful to understand why most SUDEP episodes happen at night and how certain diets can benefit people with epilepsy, especially those with Dravet syndrome, researchers say.

Attention, Behavioral Problems Common in New, Recent-Onset Juvenile Myoclonic Epilepsy
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Children with new recent-onset juvenile myoclonic epilepsy are more likely to have difficulty with executive, attention, and verbal faculties than their healthy peers and are also more likely to use a greater number of academic services, researchers found.

Also Notable

Zogenix Receives Refusal to File Letter from FDA for FINTEPLA® New Drug Application
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Zogenix announced that it received a Refusal to File letter from the FDA regarding its New Drug Application (NDA) for FINTEPLA® for the treatment of seizures associated with Dravet syndrome. Upon its preliminary review, the FDA determined that the NDA was not sufficiently complete to permit a substantive review.

Is Targeting of Compensatory Ion Channel Gene Expression a Viable Therapeutic Strategy for Dravet Syndrome?

Loss of function in the Scn1a gene leads to a severe epileptic encephalopathy called Dravet syndrome (DS). Reduced excitability in cortical inhibitory neurons is thought to be the major cause of DS seizures. Here, in contrast, researchers show enhanced excitability in thalamic inhibitory neurons that promotes the nonconvulsive seizures that are a prominent yet poorly understood feature of DS. In a mouse model of DS with a loss of function in Scn1a, reticular thalamic cells exhibited abnormally long bursts of firing caused by the downregulation of calcium-activated potassium SK channels.

The authors claim that this study supports a mechanism in which loss of potassium SK channel activity causes the reticular thalamic neurons to become hyperexcitable and promote nonconvulsive seizures in DS. They propose that reduced excitability of inhibitory neurons is not global in Dravet syndrome and that non-GABAergic mechanisms such as SK channels may be important targets for treatment.