Targeted Molecular Strategies for Genetic Neurodevelopmental Disorders: Emerging Lessons from Dravet Syndrome

Sudden unexpected death in epilepsy: respiratory vs. cardiac contributions

Sudden unexpected death in epilepsy (SUDEP) poses a significant risk to life expectancy for individuals with epilepsy. Mechanistic insight, while incomplete, has advanced through clinical observational studies and animal models. Yet we lack preventative therapies, which will depend on understanding SUDEP mechanisms. Recurrent convulsive seizures are the major SUDEP risk factor. Cardiorespiratory dysfunction precedes SUDEP, but whether cardiac arrhythmias are major proximate culprits for SUDEP remains to be determined. Here, we highlight recent data from mouse models and clinical studies that provide increasing support for respiratory depression and decreasing evidence for tachyarrhythmia-induced SUDEP. Further, we review data from genetic and chemoconvulsant mouse models that have enabled a deeper understanding for how seizures initiated in the central nervous system propagate to the autonomic nervous system and drive seizure-induced respiratory depression and subsequent SUDEP, rather than supporting a proximate cardiac arrhythmia cause. Ongoing research will continue to identify predictive SUDEP biomarkers, improve animal models, and translate basic research into precision medicine approaches. Identifying and understanding the brainstem circuits vulnerable in seizure-induced apnoea will enable therapeutic interventions to enhance the quality of life and life expectancy for individuals with epilepsy.

Emerging Genetic Therapies in Epilepsy

Advances in next-generation sequencing have allowed for genetic characterization of many epilepsies that previously had no known cause. Although having a precise diagnosis has been very helpful for management, counseling, and prognosis, until recently true precision medicine approaches that could have disease-modifying effects have been lacking. This review will highlight how preclinical animal models of Dravet syndrome have allowed some novel gene therapy approaches to be studied and further developed such that they are now entering into the clinics.

Spotlight on mechanism of sudden unexpected death in epilepsy in Dravet syndrome

Dravet syndrome (DS) is a severe and catastrophic epilepsy with childhood onset. The incidence and prevalence of sudden unexpected death in epilepsy (SUDEP) are significantly higher in DS patients than in general epileptic populations. Although extensive research conducted, the underlying mechanisms of SUDEP occurring in DS patients remain unclear. This review focuses on the link between DS and SUDEP and analyzes the potential pathogenesis. We summarize the genetic basis of DS and SUDEP and elucidate the pathophysiological mechanisms of SUDEP in DS. Furthermore, given the drug-resistant nature of this disorder, the pharmacological approach has limited efficacy and often causes side effects, therefore, the non-pharmacological approaches and precise treatment can reduce the risk of SUDEP in this condition, open a new window to cure this disease, and provide a widened landscape of treatment options for patients.

Gene therapies for neurogenetic disorders

Pathogenic variants in over 1700 genes can cause neurogenetic disorders. Monogenetic diseases are ideal targets for genetic therapies; however, the blood-brain barrier (BBB), post-mitotic neurons, and inefficient delivery platforms make gene therapies for neurogenetic diseases challenging. Following nusinersen's 2016 approval, the development of gene therapies for neurogenetic disorders has advanced rapidly, with new delivery vehicles [e.g., BBB-crossing capsids, engineered viral-like proteins, lipid nanoparticles (LNPs)] and novel therapeutic strategies (e.g., regulatory elements, novel RNA therapeutics, tRNA therapies, epigenetic and gene editing). Patient-led disease foundations have accelerated treatment development by addressing trial readiness and supporting translational research. We review the current landscape and future directions in developing gene therapies for neurogenetic disorders.

A comprehensive review of evolving treatment strategies for Dravet syndrome: Insights from randomized trials, meta-analyses, real-world evidence, and emerging therapeutic approaches

Dravet syndrome (DS) is a severe genetic developmental and epileptic encephalopathy, primarily caused by SCN1A gene mutations. Historically, treatments like clobazam and valproate have been used without evidence from randomized controlled trials (RCTs). However, the therapeutic landscape of DS has evolved with multiple RCTs demonstrating the efficacy and safety of three antiseizure medications (ASMs): stiripentol, cannabidiol (CBD), and fenfluramine. In the absence of direct comparisons between these therapies, several network meta-analyses have been conducted to compare the ASMs, while expert consensus has independently been developed to formulate treatment guidelines. While these three ASMs show promise in reducing seizures, increasing awareness of non-seizure outcomes-such as cognitive development and quality of life-has shifted the focus of evaluation. Some recent real-world studies of these ASMs have reported improvements in these non-seizure outcomes, alongside sustained efficacy and safety. However, natural history studies continue to underscore persistent deficits in these areas and highlight suboptimal long-term seizure control despite the use of these therapies. This review addresses these gaps by first discussing network meta-analyses and treatment guidelines, along with the practical limitations of these approaches. It then examines the long-term efficacy, safety, non-seizure effects, and cost-effectiveness from real-world studies of these ASMs. Finally, emerging research on novel therapeutic approaches, including genetic and serotonergic modulation, is explored. By evaluating these developments, this review aims to guide clinical decision-making and propose future directions for optimizing DS care.

Insights and progress on the biosynthesis, metabolism, and physiological functions of gamma-aminobutyric acid (GABA): a review

GABA (γ-aminobutyric acid) is a non-protein amino acid that occurs naturally in the human brain, animals, plants and microorganisms. It is primarily produced by the irreversible action of glutamic acid decarboxylase (GAD) on the α-decarboxylation of L-glutamic acid. As a major neurotransmitter in the brain, GABA plays a crucial role in behavior, cognition, and the body's stress response. GABA is mainly synthesized through the GABA shunt and the polyamine degradation pathways. It works through three receptors (GABAA, GABAB, and GABAC), each exhibiting different pharmacological and physiological characteristics. GABA has a variety of physiological roles and applications. In plants, it regulates growth, development and stress responses. In mammals, it influences physiological functions such as nervous system regulation, blood pressure equilibrium, liver and kidneys enhancement, hormone secretion regulation, immunity enhancement, cancer prevention, as well as anti-aging effects. As a biologically active ingredient, GABA possesses unique physiological effects and medicinal value, leading to its widespread application and substantially increased market demand in the food and pharmaceutical industries. GABA is primarily produced through chemical synthesis, plant enrichment and microbial fermentation. In this review, we first make an overview of GABA, focusing on its synthesis, metabolism, GABA receptors and physiological functions. Next, we describe the industrial production methods of GABA. Finally, we discuss the development of ligands for the GABA receptor binding site, the prospects of GABA production and application, as well as its clinical trials in potential drugs or compounds targeting GABA for the treatment of epilepsy. The purpose of this review is to attract researchers from various fields to focus on GABA research, promote multidisciplinary communications and collaborations, break down disciplinary barriers, stimulate innovative research ideas and methods, and advance the development and application of GABA in medicine, agriculture, food and other fields.

New epilepsy therapies in development

Epilepsy is a common brain disorder, characterized by spontaneous recurrent seizures, with associated neuropsychiatric and cognitive comorbidities and increased mortality. Although people at risk can often be identified, interventions to prevent the development of the disorder are not available. Moreover, in at least 30% of patients, epilepsy cannot be controlled by current antiseizure medications (ASMs). As a result of considerable progress in epilepsy genetics and the development of novel disease models, drug screening technologies and innovative therapeutic modalities over the past 10 years, more than 200 novel epilepsy therapies are currently in the preclinical or clinical pipeline, including many treatments that act by new mechanisms. Assisted by diagnostic and predictive biomarkers, the treatment of epilepsy is undergoing paradigm shifts from symptom-only ASMs to disease prevention, and from broad trial-and-error treatments for seizures in general to mechanism-based treatments for specific epilepsy syndromes. In this Review, we assess recent progress in ASM development and outline future directions for the development of new therapies for the treatment and prevention of epilepsy.

Caregiver perceptions of the impact of Dravet syndrome on the family, current supports and hopes and fears for the future: A qualitative study

BACKGROUND

Dravet syndrome (DS) is a Developmental and Epileptic Encephalopathy (DEE) with onset typically in infancy. Seizures are pharmaco-resistant, and neurodevelopment is compromised in almost all children. There is limited data on the impact of the condition on the family, support needs and hopes and fears in Sweden.

METHODS

Interviews were undertaken with the caregivers of 36 of 48 (75%) living children with DS in Sweden focusing on the perceived impact on the family, current supports and hopes and fears for the future. Data from the interviews were analyzed by two raters using reflexive thematic analysis.

RESULTS

The analysis revealed seven main themes focusing on the perceived negative impact the disease has on caregivers and family functioning. These negative impacts concerned: caregiver sleep (e.g., frequent night waking), siblings (e.g., gets less attention/time), social life (e.g., limited vacations), family finances (e.g., limited career progression), parental health (both mental and physical) and need for constant supervision (e.g., child's need for constant supervision for fear of seizures). Another theme concerned the impact on family relationships. Whilst some caregivers perceived the impact to be negative (e.g., limited time for each other) others felt that having a child with DS lead to stronger relationships and more 'teamwork'. With respect to supports, the caregivers identified a number of areas where they felt the family could access appropriate supports. Themes regarding supports included: support from the wider family and friends, support from DS support groups (online or in-person), support from the child's hospital or disability service and respite care (e.g., child was looked after on weekends or had paid carers in the home). Regarding hopes and fears for the future, responses focused mainly on fears, including concerns about premature death of the child, transition to adult healthcare services and care arrangements for child when parents are dead. Hopes for the future included better treatment for epilepsy and associated neurodevelopmental problems and finding a cure for DS.

CONCLUSIONS

Caregivers of children with DS report that the disease can have a very comprehensive negative impact on caregiver and family functioning. Identifying and providing the supports to ameliorate these negative impacts is vital to optimize caregiver and family wellbeing and quality of life.

Channelopathies in epilepsy: an overview of clinical presentations, pathogenic mechanisms, and therapeutic insights

Pathogenic variants in genes encoding ion channels are causal for various pediatric and adult neurological conditions. In particular, several epilepsy syndromes have been identified to be caused by specific channelopathies. These encompass a spectrum from self-limited epilepsies to developmental and epileptic encephalopathies spanning genetic and acquired causes. Several of these channelopathies have exquisite responses to specific antiseizure medications (ASMs), while others ASMs may prove ineffective or even worsen seizures. Some channelopathies demonstrate phenotypic pleiotropy and can cause other neurological conditions outside of epilepsy. This review aims to provide a comprehensive exploration of the pathophysiology of seizure generation, ion channels implicated in epilepsy, and several genetic epilepsies due to ion channel dysfunction. We outline the clinical presentation, pathogenesis, and the current state of basic science and clinical research for these channelopathies. In addition, we briefly look at potential precision therapy approaches emerging for these disorders.