The findings support ATP6V0C as a relevant gene in the landscape of childhood epilepsies with fever sensitivity and highlight the importance of accurate molecular diagnosis in children presenting with fever-sensitive seizures, with potential implications for future precision therapies.
Abstract
Objective
Fever can trigger seizures in several early-onset epilepsies. SCN1A-related epilepsies, including Dravet Syndrome, are the best characterised conditions in this spectrum, but a growing number of genes implicated in fever-sensitive epilepsies have emerged. We assessed the genetic heterogeneity of individuals who underwent testing because of seizures or epilepsy with fever sensitivity. In particular, we investigated the occurrence of ATP6V0C pathogenic variants and delineated its associated electro clinical features.
Methods
We retrospectively reviewed individuals tested with epilepsy-targeted Next Generation Sequencing (NGS) panels and/or Whole Exome Sequencing (WES) between 2022 and 2025, selecting those with documented fever sensitivity (defined as seizure occurrence or exacerbation temporally linked to febrile episodes in subjects who suffer from both febrile and afebrile seizures). Variants were filtered for frequency, evaluated through segregation and prediction tools, and classified according to ACMG guidelines.
Results
Among 721 individuals tested with NGS or WES for neurological indications, 418 (58%) had a history of seizures, including 53 (7.3%) with fever-sensitive epilepsy. Pathogenic or likely pathogenic variants were identified in 30% of these cases. Notably, ATP6V0C variants accounted for 2/16 (12.5%) of all pathogenic/likely pathogenic findings and were identified in 3.8% of tested fever-sensitive epilepsy patients, ranking among the most frequently implicated genes in this cohort.
Significance
Our findings support ATP6V0C as a relevant gene in the landscape of childhood epilepsies with fever sensitivity. The associated phenotype appears characterized by early febrile-triggered motor seizures, initially normal EEG followed by multifocal abnormalities, normal MRI and subsequent onset of neurodevelopmental impairment. These results highlight the importance of accurate molecular diagnosis in children presenting with fever-sensitive seizures, with potential implications for future precision therapies.
Pathogenic SV2A gene variants have been reported as causes of epilepsy and are often associated with drug resistance and susceptibility to fever-related seizures. No highly effective treatments have been established for this condition. We report a female patient with a family history of epilepsy who developed generalized seizures associated with fever and bathing from 6 months of age. Despite intensive treatment with multiple anti-seizure medications, the seizures remained refractory. Given the severe drug-resistant epilepsy characterized by fever sensitivity, seizure clustering, and multiple seizure types suggestive of Dravet syndrome, fenfluramine (FFA) was initiated at 2 years and 2 months of age. FFA at 0.2 mg/kg/day resulted in immediate and sustained seizure freedom. Subsequent whole-exome sequencing identified a pathogenic SV2A variant (p.Gly660Arg). This is the first report demonstrating the clinical efficacy of FFA for epilepsy associated with an SV2A variant. We propose that FFA's effectiveness stems from its ability to address two core pathologies of SV2A deficiency: correction of the excitatory/inhibitory imbalance by restoring inhibitory tone through its serotonergic mechanism, and mitigation of neuroinflammation, thereby stabilizing the neuronal network. FFA may represent a promising therapeutic option for patients with SV2A variant-associated epilepsy, particularly those with a fever-sensitive, drug-refractory phenotype; however, further studies with larger case series are needed to confirm its efficacy.
A comprehensive understanding of the clinical spectrum and genotype-phenotype correlation in KCNT1-related disorders is offered and the need to develop multisource data methodologies and registries to reduce follow-up loss in real-world data collections based on health records is highlighted.
Mathilde Gras, Gaëlle Quentin-Romand, N. Chemaly et al.· Brain Communications· 0 citations
CACNA1C is potentially a candidate causative gene of focal epilepsy and the genotype-phenotype correlation of CACNA1C helps explain phenotypic heterogeneity.
Yanfang Li, Pei Mo, Lan-Zhen Zhang et al.· Journal of Medical Genetics· 0 citations
Background/Objectives: In resource-limited regions, limited access to genetic testing may delay etiological diagnosis in selected patients with epilepsy and complex neurological manifestations, particularly when the phenotype raises suspicion of an underlying genetic etiology. This study aimed to assess the diagnostic value and clinical utility of phenotype-guided WES in selected patients aged ≥17 years with epilepsy and complex neurological manifestations in Southern Kazakhstan and to characterize clinical, therapeutic, and molecular features associated with drug-resistant epilepsy (DRE). Methods: This observational cohort included 78 patients aged ≥17 years with epilepsy and complex neurological manifestations identified through 25 outpatient medical centers. After enrollment, all patients underwent structured HPO-based phenotyping, assessment of antiseizure medication exposure, seizure burden, treatment response, and proband-only WES. Variants were interpreted according to ACMG/AMP guidelines. Exploratory multivariable logistic regression was used to assess factors associated with DRE. Results: P/LP variants were identified in 12/78 patients, corresponding to a diagnostic yield of 15.4%. VUS were detected in 16/78 patients (20.5%). DRE was present in 41 patients (52.6%), all of whom were receiving polytherapy. Carbamazepine was the most frequently used antiseizure medication (52/78, 66.7%), followed by valproic acid (32/78, 41.0%) and levetiracetam (20/78, 25.6%). Patients with DRE had earlier seizure onset, more frequent definite structural MRI abnormalities, and a higher proportion of P/LP variants. In the adjusted model, P/LP variant presence and definite structural MRI abnormality were associated with DRE. Conclusions: Phenotype-guided proband-only WES provided clinically relevant diagnostic information in a real-world epilepsy cohort with complex neurological manifestations in a resource-limited outpatient setting. The observed burden of DRE and polytherapy supports the potential value of integrating therapeutic profiling, neuroimaging, and genomic testing in the etiological evaluation of patients with epilepsy and additional neurological features.
I.A. Doszhanov, Sandugash Rustemova, Nigara Yerkhojayeva et al.· International Journal of Tra...· 0 citations
SCN1A-confirmed DS is associated with substantial seizure burden and neurodevelopmental morbidity, and delayed molecular diagnosis may lead to inappropriate treatment exposure and seizure worsening.
Esma Şengenç, Şeyma Sönmez Şahin, A. Iscan et al.· Turkish archives of pediatri...· 0 citations
Background and Objectives KCNT1-related epilepsy is an ultra-rare pediatric-onset developmental and epileptic encephalopathy with a broad clinical phenotype ranging from, most commonly, severe infantile-onset epilepsy and global developmental delay to, less commonly, milder phenotypes including sleep-related seizures, autism spectrum disorder, and learning disability. We initiated the first-ever prospective natural history study to comprehensively clinically phenotype individuals affected by this disorder. Methods The primary aim of this study was to characterize seizures in individuals with KCNT1-related epilepsy. Secondary and exploratory aims included characterization of the full spectrum of disease symptoms, understanding caregiver burden, and collection of blood and urine samples for biomarker exploration. All study activities were conducted remotely (e.g., home-based assessments, telehealth visits). Results Thirty-five participants (n = 20 male, 15 female) were enrolled in this study. The average age at the baseline visit was 76.0 months (s.d. = 75.5). This article presents the study design and methods and several challenges that arose in its implementation and discusses various solutions implemented in this medically complex population. Discussion Future work will apply the lessons from this study in the planning and design of clinical trials for KCNT1-related epilepsy and possibly other developmental and epileptic encephalopathies.
Heather R. Adams, Viet Nguyen, L. Seltzer et al.· Neurology: Genetics· 0 citations