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Epilepsy of infancy with migrating focal seizures: A scoping review of clinical features, diagnostic testing including genetics, long-term outcomes, mortality, and current and emerging therapeutic strategies.

BACKGROUND: Epilepsy of infancy with migrating focal seizures (EIMFS) is among the most severe developmental and epileptic encephalopathies (DEEs), marked by intractable multifocal seizures migrating across both hemispheres, profound developmental arrest, and high early mortality. Advances in next-generation sequencing have revealed a heterogeneous genetic architecture dominated by KCNT1 gain-of-function variants across more than 30 implicated genes, creating opportunities for precision therapeutics. OBJECTIVE: To systematically map published evidence on the clinical, electrophysiological, neuroimaging, genetic, and therapeutic landscape of EIMFS, and to delineate critical knowledge gaps and future research priorities. METHODS: A scoping review was conducted following the Arksey and O'Malley framework, searching PubMed, Ovid MEDLINE, Embase, Cochrane Library/CENTRAL, and ClinicalTrials.gov. RESULTS: Of 643 articles screened, 89 met inclusion criteria. Beyond confirmation of the canonical electroclinical phenotype, several gaps emerged: neonatal versus post-neonatal onset stratification by genetic etiology remains largely uncharacterized; genotype-specific EEG biomarkers are lacking except for a single small KCNT1 study; and the clinical significance of atypical EEG features-including burst suppression and hypsarrhythmia-is undefined. Neuroimaging literature documents progressive cerebral atrophy and myelination abnormalities without quantitative volumetry, diffusion tractography markers, or attribution to seizure burden, medication effects, or underlying etiology. Genetic diagnostic yield was 70-80%, with KCNT1 accounting for 30-50% of solved cases; however, genotype-outcome stratification is limited. Seizures were broadly refractory; potassium bromide, ketogenic diet, cannabidiol, and quinidine (in KCNT1-confirmed cases) showed partial efficacy. Emerging precision approaches include sodium channel blockers for SCN2A gain-of-function variants, novel small molecules, fluoxetine, antisense oligonucleotides, and divalent siRNA targeting KCNT1. Systemic-to-pulmonary collateral circulation causing severe cardiopulmonary complications was reported across multiple cases, yet no consensus screening protocol exists. CONCLUSIONS: EIMFS remains one of the most refractory epilepsy syndromes of infancy. Precision genetic diagnosis is essential to guide targeted therapy. International collaborative registries, standardized outcome measures, genotype-stratified biomarker studies, and rapid point-of-care genomic testing are urgently needed to advance evidence-based care for this highly vulnerable population.

Humans

Early infantile developmental and epileptic encephalopathy: clinical spectrum, diagnosis, outcomes, and evolving treatment strategies.

Early infantile developmental and epileptic encephalopathy (EIDEE) is among the most severe epilepsy syndromes, with onset before three months of age and an estimated incidence of approximately 10 per 100,000 live births. The 2022 International League Against Epilepsy classification unified the historically distinct Ohtahara syndrome and early myoclonic encephalopathy under a single diagnostic framework defined by frequent drug-resistant tonic and/or myoclonic seizures, an abnormal neurological examination, and an abnormal interictal electroencephalogram-most characteristically a burst-suppression pattern. This narrative review synthesizes the clinical, electrophysiological, neuroimaging, genetic, and therapeutic literature within the EIDEE framework. The clinical phenotype is characterized by central hypotonia, postnatal microcephaly, cortical visual impairment, and age-dependent syndromic evolution toward infantile epileptic spasms syndrome or Lennox-Gastaut syndrome in the majority of patients. Electroencephalography remains essential for syndromic classification, while systematic metabolic screening and early trio whole-exome or whole-genome sequencing are central to the etiologic workup, achieving diagnostic yields of 60-65%. The most commonly identified genetic causes include STXBP1, KCNQ2, and SCN2A variants. Outcomes are poor overall and strongly etiology-dependent: vitamin-responsive disorders carry a substantially more favorable prognosis, whereas mortality reaches 25% in genetic cohorts. Genotype-guided pharmacotherapy is now applicable to a clinically meaningful subset of patients, with sodium channel blockers, potassium channel openers, and emerging antisense oligonucleotide therapies representing important therapeutic advances. Gene therapy trials are underway but have encountered early safety signals, underscoring the vulnerability of this population. Critical unmet needs include earlier molecular diagnosis, precision therapies targeting developmental outcomes beyond seizure control, and prospective international registries to characterize the long-term natural history of EIDEE.

Humans

Treatment updates in myotonic disorders.

Myotonia is delayed muscle relaxation after forceful contraction. It is due to hyperexcitability of the skeletal muscle membrane. It can arise from primary skeletal muscle ion channel dysfunction, involving chloride or sodium channels, but is also a prominent clinical feature in myotonic dystrophies where altered RNA splicing leads to secondary ion channel dysregulation amongst other systemic manifestations. Clinically, myotonia can range from delayed eye opening to a disabling symptom causing impaired mobility, functional difficulty and sometimes pain. It can also be a "hidden disability" with many patients feeling socially embarrassed by "looking healthy", yet being unable to do everyday physical tasks or to do them as effortlessly as their peers. It is a symptom that almost always indicates a genetic diagnosis, although it can occur in acquired conditions, including metabolic and drug-induced causes. To experience myotonia without knowing what it is can be baffling. To receive a genetic diagnosis associated with it can be life changing. Although there is no cure, there are many effective and available symptomatic treatments for myotonia and currently we are in an exciting era of clinical trials for new molecular disease-modifying therapies for myotonic dystrophy type 1. In this review, we consider recent developments in the treatment of myotonic disorders and how they may change clinical practice.

Humans

Unplugging lateral fenestrations of NALCN reveals a hidden drug binding site within the pore region.

The sodium (Na+) leak channel (NALCN) is a member of the four-domain voltage-gated cation channel family that includes the prototypical voltage-gated sodium and calcium channels (NaVs and CaVs, respectively). Unlike NaVs and CaVs, which have four lateral fenestrations that serve as routes for lipophilic compounds to enter the central cavity to modulate channel function, NALCN has bulky residues (W311, L588, M1145, and Y1436) that block these openings. Structural data suggest that occluded fenestrations underlie the pharmacological resistance of NALCN, but functional evidence is lacking. To test this hypothesis, we unplugged the fenestrations of NALCN by substituting the four aforementioned residues with alanine (AAAA) and compared the effects of NaV, CaV, and NALCN blockers on both wild-type (WT) and AAAA channels. Most compounds behaved in a similar manner on both channels, but phenytoin and 2-aminoethoxydiphenyl borate (2-APB) elicited additional, distinct responses on AAAA channels. Further experiments using single alanine mutants revealed that phenytoin and 2-APB enter the inner cavity through distinct fenestrations, implying structural specificity to their modes of access. Using a combination of computational and functional approaches, we identified amino acid residues critical for 2-APB activity, supporting the existence of drug binding site(s) within the pore region. Intrigued by the activity of 2-APB and its analogues, we tested compounds containing the diphenylmethane/amine moiety on WT channels. We identified clinically used drugs that exhibited diverse activity, thus expanding the pharmacological toolbox for NALCN. While the low potencies of active compounds reiterate the pharmacological resistance of NALCN, our findings lay the foundation for rational drug design to develop NALCN modulators with refined properties.

Binding Sites