Differences in manifestations of epilepsy and developmental delay in PURA syndrome and 5q31 microdeletions.

PURA is mapped to chromosome 5q31 and plays a vital role in neuronal development and synapse formation. Here, we aim to explore PURA's impact on cognitive development and epilepsy phenotype by comparing patients with single nucleotide variants (SNPs) in the PURA gene (PURA-SNP patients) to those with 5q31 microdeletions including PURA (5q31del + PURA) and those with 5q31 microdeletions not including the PURA gene (5q31del-PURA). A systematic literature search was conducted in PubMed. Two separate searches were performed in order to find patients with PURA SNPs and 5q31 microdeletions. This review includes data from 191 patients collected from a total of 18 articles; 174 of the patients had PURA SNPs, 13 had 5q31 microdeletions involving the PURA gene, and 4 had 5q31 microdeletions without PURA gene implication. All patients exhibited hypotonia, feeding difficulties and dysmorphic features, however epilepsy was primarily present in patients with PURA syndrome, that is, groups PURA-SNP and 5q31del + PURA. Regarding the developmental milestones the 5q31del + PURA group stood out as being the most severe, while the 5q31del-PURA group showed a relatively mild phenotype. Our findings support the hypothesis of PURA being the key contributor of developmental delay and epilepsy among patients with PURA syndrome.

KCNT2-Related Disorders: Phenotypes, Functional, and Pharmacological Properties.

OBJECTIVE: Pathogenic variants in KCNT2 are rare causes of developmental epileptic encephalopathy (DEE). We herein describe the phenotypic and genetic features of patients with KCNT2-related DEE, and the in vitro functional and pharmacological properties of KCNT2 channels carrying 14 novel or previously untested variants. METHODS: Twenty-five patients harboring KCNT2 variants were investigated: 12 were identified through an international collaborative network, 13 were retrieved from the literature. Clinical data were collected and included in a standardized phenotyping sheet. Novel variants were detected using exome sequencing and classified using ACMG criteria. Functional and pharmacological studies were performed by whole-cell electrophysiology in HEK-293 and SH-SY5Y cells. RESULTS: The phenotypic spectrum encompassed: (a) intellectual disability/developmental delay (21/22 individuals with available information), ranging from mild to severe/profound; (b) epilepsy (15/25); (c) neurological impairment, with altered muscle tone (14/22); (d) dysmorphisms (13/20). Nineteen pathogenic KCNT2 variants were found (9 new, 10 reported previously): 16 missense, 1 in-frame deletion of a single amino acid, 1 nonsense, and 1 frameshift. Among tested variants, 8 showed gain-of-function (GoF), and 6 loss-of-function (LoF) features when expressed heterologously in vitro. Quinidine and fluoxetine blocked all GoF variants, whereas loxapine and riluzole activated some LoF variants while blocking others. INTERPRETATION: We expanded the phenotypic and genotypic spectrum of KCNT2-related disorders, highlighting novel genotype-phenotype associations. Pathogenic KCNT2 variants cause GoF or LoF in vitro phenotypes, and each shows a unique pharmacological profile, suggesting the need for in vitro functional and pharmacological investigation to enable targeted therapies based on the molecular phenotype. ANN NEUROL 2023;94:332-349.

Prediction tools and risk stratification in epilepsy surgery.

OBJECTIVE: This study was undertaken to conduct external validation of previously published epilepsy surgery prediction tools using a large independent multicenter dataset and to assess whether these tools can stratify patients for being operated on and for becoming free of disabling seizures (International League Against Epilepsy stage 1 and 2). METHODS: We analyzed a dataset of 1562 patients, not used for tool development. We applied two scales: Epilepsy Surgery Grading Scale (ESGS) and Seizure Freedom Score (SFS); and two versions of Epilepsy Surgery Nomogram (ESN): the original version and the modified version, which included electroencephalographic data. For the ESNs, we used calibration curves and concordance indexes. We stratified the patients into three tiers for assessing the chances of attaining freedom from disabling seizures after surgery: high (ESGS = 1, SFS = 3-4, ESNs > 70%), moderate (ESGS = 2, SFS = 2, ESNs = 40%-70%), and low (ESGS = 2, SFS = 0-1, ESNs < 40%). We compared the three tiers as stratified by these tools, concerning the proportion of patients who were operated on, and for the proportion of patients who became free of disabling seizures. RESULTS: The concordance indexes for the various versions of the nomograms were between .56 and .69. Both scales (ESGS, SFS) and nomograms accurately stratified the patients for becoming free of disabling seizures, with significant differences among the three tiers (p < .05). In addition, ESGS and the modified ESN accurately stratified the patients for having been offered surgery, with significant difference among the three tiers (p < .05). SIGNIFICANCE: ESGS and the modified ESN (at thresholds of 40% and 70%) stratify patients undergoing presurgical evaluation into three tiers, with high, moderate, and low chance for favorable outcome, with significant differences between the groups concerning having surgery and becoming free of disabling seizures. Stratifying patients for epilepsy surgery has the potential to help select the optimal candidates in underprivileged areas and better allocate resources in developed countries.

Clinical utility of ultra long-term subcutaneous electroencephalographic monitoring in drug-resistant epilepsies: a "real world" pilot study.

OBJECTIVE: This study was undertaken to assess the clinical utility, safety, and tolerability in epilepsy patients of ultra long-term monitoring with a novel subcutaneous electroencephalographic (EEG) device (sqEEG). METHODS: Five patients with drug-resistant focal epilepsy were implanted (one patient bilaterally) with sqEEG. In phase 1, we assessed sqEEG sensitivity for seizure recording by recording seizures simultaneously with scalp EEG in the epilepsy monitoring unit (EMU). sqEEG was scored either visually (v-sqEEG) or by using a semiautomatic algorithm (EpiSight; E-sqEEG). In phase 2, the patients were monitored as outpatients for 3-6 months. sqEEG data were analyzed monthly, evaluating concordance of data obtained by v-sqEEG, E-sqEEG, and patients' diaries. v-sqEEG data were used to guide treatment adjustments. sqEEG-related side effects were assessed throughout the study. RESULTS: In phase 1, v-sqEEG detected all seizures recorded in the EMU in all patients, whereas E-sqEEG was as effective in three patients. In the other two patients, E-sqEEG detected only a proportion or none of the seizures, respectively. Sensitivity of E-sqEEG depended on the ictal EEG features. In phase 2, a 100% concordance between E-sqEEG and v-sqEEG in seizure detection was observed for the same three patients as in phase 1. In the other two patients (one implanted bilaterally), effectiveness of E-sqEEG in detecting seizure as compared to v-sqEEG ranged from 0% to 83%. v-sqEEG showed that all patients reported in their diaries fewer seizures than they actually suffered. In four of five patients, v-sqEEG showed that the treatment adjustments had been ineffective or associated with a seizure increment. The only side effect was an infection at the implantation site in one patient. SIGNIFICANCE: The sqEEG system could collect reliable information on seizure activity, thus providing clinically relevant information. Sensitivity of EpiSight in detecting seizures varied across patients, depending on the ictal EEG features. sqEEG ultra long-term monitoring was feasible and well tolerated.

Quantitative EEG biomarkers for STXBP1-related disorders.

OBJECTIVE: EEG patterns and quantitative EEG (qEEG) features have been poorly explored in monogenic epilepsies. Herein, we investigate regional differences in EEG frequency composition in patients with STXBP1 developmental and epileptic encephalopathy (STXBP1-DEE). METHODS: We conducted a retrospective study collecting electroclinical data of patients with STXBP1-DEE and two control groups of patients with DEEs of different etiologies and typically developing individuals matched for age and sex. We performed a (1) visual EEG assessment, (b) qEEG analysis, and (c) electrical source imaging (ESI). We quantified the relative power (RP) of four frequency bands (α ß, θ, δ), in two electrode groups (anterior/posterior), and compared their averages and dynamics (standard deviation [SD] over time). The ESI was performed by applying the standard Distributed Source Modeling algorithm. RESULTS: We analyzed 42 EEG studies in 19 patients with STXBP1-DEE (10 female), with a median age at recordings of 9.6 years (range 9 months to 29 years). The δRP was higher in recordings of STXBP1-DEE (p < .001) compared to both control groups, suggesting the pathogenicity and STXBP1-specificity of these findings. In STXBP1-DEE, the δRP was significantly higher in the anterior electrode group compared to the posterior one (p = .003). There was no correlation between the anterior δRP and the epilepsy focus, age at recordings, and concomitant medications The ESI modeling of this activity showed a widespread involvement of the dorsomesial frontal cortex, suggesting a large corticosubcortical pathologic network. Finally, we identified two groups of recordings: cluster.1 with higher anterior δRP and low dynamics and cluster.2 with lower δRP and higher dynamics. Patients in cluster.1 had a more severe epilepsy and neurological phenotype compared to patients in cluster 2. SIGNIFICANCE: The qEEG analysis showed a predominant frontal slow activity as a specific STXBP1 feature that correlates with the severity of the phenotype and may represent a biomarker for prospective longitudinal studies of STXBP1-DEE.

Early mortality in STXBP1-related disorders.

INTRODUCTION: Pathogenic variants in STXBP1 cause a spectrum of disorders mainly consisting of developmental and epileptic encephalopathy (DEE), often featuring drug-resistant epilepsy. An increased mortality risk occurs in individuals with drug-resistant epilepsy and DEE, with sudden unexpected death in epilepsy (SUDEP) often the major cause of death. This study aimed to identify the rate and causes of mortality in STXBP1-related disorders. METHODS: Through an international call, we analyzed data on individuals with STXBP1 pathogenic variants, who passed away from causes related to their disease. RESULTS: We estimated a mortality rate of 3.2% (31/966), based on the STXBP1 Foundation and the STXBP1 Global Connect registry. In total, we analyzed data on 40 individuals (23 males) harboring pathogenic STXBP1 variants, collected from different centers worldwide. They died at a median age of 13 years (range: 11 months-46 years). The most common cause of death was SUDEP (36%), followed by pulmonary infections and respiratory complications (33%). The incidence of SUDEP peaked in mid-childhood, while non-SUDEP causes were more frequent in early childhood or adulthood (p = 0.006). In the most severe phenotypes, death was related to non-SUDEP causes (p = 0.018). CONCLUSION: We found a mortality rate in STXBP1-related disorders similar to other DEEs, with an early age at death and SUDEP as well as pulmonary infections as the main cause of death. These findings assist in prognostic evaluation and genetic counseling for the families. They help to define the mortality risk of STXBP1-related disorders and implement preventative strategies.

POU3F3-related disorder: Defining the phenotype and expanding the molecular spectrum.

POU3F3 variants cause developmental delay, behavioral problems, hypotonia and dysmorphic features. We investigated the phenotypic and genetic landscape, and genotype-phenotype correlations in individuals with POU3F3-related disorders. We recruited unpublished individuals with POU3F3 variants through international collaborations and obtained updated clinical data on previously published individuals. Trio exome sequencing or single exome sequencing followed by segregation analysis were performed in the novel cohort. Functional effects of missense variants were investigated with 3D protein modeling. We included 28 individuals (5 previously published) from 26 families carrying POU3F3 variants; 23 de novo and one inherited from an affected parent. Median age at study inclusion was 7.4 years. All had developmental delay mainly affecting speech, behavioral difficulties, psychiatric comorbidities and dysmorphisms. Additional features included gastrointestinal comorbidities, hearing loss, ophthalmological anomalies, epilepsy, sleep disturbances and joint hypermobility. Autism, hearing and eye comorbidities, dysmorphisms were more common in individuals with truncating variants, whereas epilepsy was only associated with missense variants. In silico structural modeling predicted that all (likely) pathogenic variants destabilize the DNA-binding region of POU3F3. Our study refined the phenotypic and genetic landscape of POU3F3-related disorders, it reports the functional properties of the identified pathogenic variants, and delineates some genotype-phenotype correlations.

IRF2BPL as a novel causative gene for progressive myoclonus epilepsy.

IRF2BPL has recently been described as a novel cause of neurodevelopmental disorders with multisystemic regression, epilepsy, cerebellar symptoms, dysphagia, dystonia, and pyramidal signs. We describe a novel IRF2BPL phenotype consistent with progressive myoclonus epilepsy (PME) in three novel subjects and review the features of the 31 subjects with IRF2BPL-related disorders previously reported. Our three probands, aged 28-40 years, harbored de novo nonsense variants in IRF2BPL (c.370C > T, p.[Gln124*] and c.364C > T; p.[Gln122*], respectively). From late childhood/adolescence, they presented with severe myoclonus epilepsy, stimulus-sensitive myoclonus, and progressive cognitive, speech, and cerebellar impairment, consistent with a typical PME syndrome. The skin biopsy revealed massive intracellular glycogen inclusions in one proband, suggesting a similar pathogenic pathway to other storage disorders. Whereas the two older probands were severely affected, the younger proband had a milder PME phenotype, partially overlapping with some of the previously reported IRF2BPL cases, suggesting that some of them might be unrecognized PME. Interestingly, all three patients harbored protein-truncating variants clustered in a proximal, highly conserved gene region around the "coiled-coil" domain. Our data show that PME can be an additional phenotype within the spectrum of IRF2BPL-related disorders and suggest IRF2BPL as a novel causative gene for PME.

Encephalopathy related to status epilepticus during slow sleep (ESES). Pathophysiological insights and nosological considerations.

Encephalopathy related to Status Epilepticus during slow Sleep (ESES) is a childhood epilepsy syndrome characterized by the appearance of cognitive, behavioral, and motor disturbances in conjunction with a striking activation of EEG epileptic abnormalities during non-REM sleep. After more than 50 years since the first description, the pathophysiological mechanisms underlying the appearance of encephalopathy in association with a sleep-related enhancement of epileptic discharges are incompletely elucidated. Recent experimental data support the hypothesis that the development of the ESES encephalopathic picture depends on a spike-induced impairment of the synaptic homeostasis processes occurring during normal sleep and that is particularly pronounced during the developmental age. During sleep, synaptic homeostasis is promoted by synaptic weakening/elimination after the increment of synaptic strength that occurs during wakefulness. The EEG can display modifications in synaptic strength by changes in sleep slow wave activity (SWA). Recent studies during active ESES have failed to show changes in sleep SWA, while these changes occurred again after recovery from ESES, thus supporting a spike-related interference on the normal homeostatic processes of sleep. This impairment, during the developmental period, can lead to disruption of cortical wiring and brain plastic remodeling, which lead to the, often irreversible, neuropsychological compromise typical of ESES. From the nosographic point of view, these pathophysiological data lend support to the maintenance of the term ESES, i.e., "encephalopathy related to status epilepticus during sleep". Indeed, this term conveys the concept that the extreme activation of epileptic discharges during sleep is directly responsible for the encephalopathy, hence the importance of defining this condition as an encephalopathy related to the exaggerated activation of epileptic activity during sleep. In this respect, ESES represents a genuine example of a "pure" epileptic encephalopathy in which sleep-related epileptic activity "per se" has a crucial role in determining the encephalopathic picture. This paper was presented at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022.

PRRT2 benign familial infantile seizures (BFIS) with atypical evolution to encephalopathy related to status epilepticus during sleep (ESES).

PURPOSE: Heterozygous variants in PRRT2 are mostly associated with benign phenotypes, being the major genetic cause of benign familial infantile seizures (BFIS), as well as in paroxysmal disorders. We report two children from unrelated families with BFIS that evolved to encephalopathy related to status epilepticus during sleep (ESES). METHODS AND RESULTS: Two probands presented with focal motor seizures at 3 months of age, with a limited course. Both children presented, at around 5 years of age, with centro-temporal interictal epileptiform discharges with a source in the frontal operculum, markedly activated by sleep, and associated with stagnation on neuropsychological development. Whole-exome sequencing and co-segregation analysis revealed a frameshift mutation c.649dupC in the proline-rich transmembrane protein 2 (PRRT2) in both probands and all affected family members. CONCLUSION: The mechanism leading to epilepsy and the phenotypic variability of PRRT2 variants remain poorly understood. However, its wide cortical and subcortical expression, in particular in the thalamus, could partially explain both the focal EEG pattern and the evolution to ESES. No variants in the PRRT2 gene have been previously reported in patients with ESES. Due to the rarity of this phenotype, other possible causative cofactors are likely contributing to the more severe course of BFIS in our probands.

Web-based decision support system for patient-tailored selection of antiseizure medication in adolescents and adults: An external validation study.

BACKGROUND AND PURPOSE: Antiseizure medications (ASMs) should be tailored to individual characteristics, including seizure type, age, sex, comorbidities, comedications, drug allergies, and childbearing potential. We previously developed a web-based algorithm for patient-tailored ASM selection to assist health care professionals in prescribing medication using a decision support application (https://epipick.org). In this validation study, we used an independent dataset to assess whether ASMs recommended by the algorithm are associated with better outcomes than ASMs considered less desirable by the algorithm. METHODS: Four hundred twenty-five consecutive patients with newly diagnosed epilepsy were followed for at least 1 year after starting an ASM chosen by their physician. Patient characteristics were fed into the algorithm, blinded to the physician's ASM choices and outcome. The algorithm recommended ASMs, ranked in hierarchical groups, with Group 1 ASMs labeled as the best option for that patient. We evaluated retention rates, seizure freedom rates, and adverse effects leading to treatment discontinuation. Survival analysis contrasted outcomes between patients who received favored drugs and those who received lower ranked drugs. Propensity score matching corrected for possible imbalances between the groups. RESULTS: Antiseizure medications classified by the algorithm as best options had a higher retention rate (79.4% vs. 67.2%, p = 0.005), higher seizure freedom rate (76.0% vs. 61.6%, p = 0.002), and lower rate of discontinuation due to adverse effects (12.0% vs. 29.2%, p < 0.001) than ASMs ranked as less desirable by the algorithm. CONCLUSIONS: Use of the freely available decision support system is associated with improved outcomes. This drug selection application can provide valuable assistance to health care professionals prescribing medication for individuals with epilepsy.

KCNT1-related epilepsies and epileptic encephalopathies: phenotypic and mutational spectrum.

Variants in KCNT1, encoding a sodium-gated potassium channel (subfamily T member 1), have been associated with a spectrum of epilepsies and neurodevelopmental disorders. These range from familial autosomal dominant or sporadic sleep-related hypermotor epilepsy to epilepsy of infancy with migrating focal seizures (EIMFS) and include developmental and epileptic encephalopathies. This study aims to provide a comprehensive overview of the phenotypic and genotypic spectrum of KCNT1 mutation-related epileptic disorders in 248 individuals, including 66 previously unpublished and 182 published cases, the largest cohort reported so far. Four phenotypic groups emerged from our analysis: (i) EIMFS (152 individuals, 33 previously unpublished); (ii) developmental and epileptic encephalopathies other than EIMFS (non-EIMFS developmental and epileptic encephalopathies) (37 individuals, 17 unpublished); (iii) autosomal dominant or sporadic sleep-related hypermotor epilepsy (53 patients, 14 unpublished); and (iv) other phenotypes (six individuals, two unpublished). In our cohort of 66 new cases, the most common phenotypic features were: (i) in EIMFS, heterogeneity of seizure types, including epileptic spasms, epilepsy improvement over time, no epilepsy-related deaths; (ii) in non-EIMFS developmental and epileptic encephalopathies, possible onset with West syndrome, occurrence of atypical absences, possible evolution to developmental and epileptic encephalopathies with sleep-related hypermotor epilepsy features; one case of sudden unexplained death in epilepsy; (iii) in autosomal dominant or sporadic sleep-related hypermotor epilepsy, we observed a high prevalence of drug-resistance, although seizure frequency improved with age in some individuals, appearance of cognitive regression after seizure onset in all patients, no reported severe psychiatric disorders, although behavioural/psychiatric comorbidities were reported in ∼50% of the patients, sudden unexplained death in epilepsy in one individual; and (iv) other phenotypes in individuals with mutation of KCNT1 included temporal lobe epilepsy, and epilepsy with tonic-clonic seizures and cognitive regression. Genotypic analysis of the whole cohort of 248 individuals showed only missense mutations and one inframe deletion in KCNT1. Although the KCNT1 mutations in affected individuals were seen to be distributed among the different domains of the KCNT1 protein, genotype-phenotype considerations showed many of the autosomal dominant or sporadic sleep-related hypermotor epilepsy-associated mutations to be clustered around the RCK2 domain in the C terminus, distal to the NADP domain. Mutations associated with EIMFS/non-EIMFS developmental and epileptic encephalopathies did not show a particular pattern of distribution in the KCNT1 protein. Recurrent KCNT1 mutations were seen to be associated with both severe and less severe phenotypes. Our study further defines and broadens the phenotypic and genotypic spectrums of KCNT1-related epileptic conditions and emphasizes the increasingly important role of this gene in the pathogenesis of early onset developmental and epileptic encephalopathies as well as of focal epilepsies, namely autosomal dominant or sporadic sleep-related hypermotor epilepsy.

Pseudoresistance in idiopathic/genetic generalized epilepsies - Definitions, risk factors, and outcome.

OBJECTIVE: The aim of the study was to determine risk factors associated with pseudoresistance in a large, representative cohort of patients with Idiopathic/Genetic Generalized Epilepsy (IGE) and the impact of pseudoresistance on socioeconomic parameters. METHODS: We performed a literature review on definitions of pseudoresistance in IGE. In an established cohort of patients with IGE from Funen, patients with current or previous pseudoresistant seizures were retrospectively identified based on a comprehensive evaluation of the patients' medical records and direct patient contact, if required. In addition, clinical characteristics, socioeconomic, and demographic data were assessed. Personal interviews were used to determine the brief version of Barratts (BIS-8) impulsivity score. RESULTS: The literature review provided the following definition of pseudoresistance: Seizures due to (I) lacking adherence to antiseizure medication (ASM), (II) incompliance to general rule of conduct, (III) psychogenic nonepileptic seizures (PNES), (IV) inadequate choice of ASM/dosage, and (V) incorrect classification of epilepsy. Applying criteria I-III to a cohort of patients with IGE (n = 499), 73 patients (14.6%) were currently pseudoresistant and 62 (12.4%) were previously pseudoresistant, but currently seizure free. Current pseudoresistance was associated with younger age, drug/alcohol abuse, lower rate of full-time employment, and higher BIS-8 scores. We found no associations of pseudoresistance with juvenile myoclonic epilepsy, psychiatric disease, specific seizure types, or number of seizure types. Patients with previously pseudoresistant seizures have tried more ASMs and were characterized by male preponderance, higher BIS-8, and higher rates of abuse. Surrogate markers for social outcome did not differ. SIGNIFICANCE: In IGE, pseudoresistance may be defined as PNES or insufficient adherence to medication/conduct and is associated with younger age, drug/alcohol abuse, and higher scores for impulsivity. If transient, its impact on socioeconomic status remains limited but may be associated with a risk of overtreatment with ASM.

Functional Effects of Epilepsy Associated KCNT1 Mutations Suggest Pathogenesis via Aberrant Inhibitory Neuronal Activity.

KCNT1 (K+ channel subfamily T member 1) is a sodium-activated potassium channel highly expressed in the nervous system which regulates neuronal excitability by contributing to the resting membrane potential and hyperpolarisation following a train of action potentials. Gain of function mutations in the KCNT1 gene are the cause of neurological disorders associated with different forms of epilepsy. To gain insights into the underlying pathobiology we investigated the functional effects of 9 recently published KCNT1 mutations, 4 previously studied KCNT1 mutations, and one previously unpublished KCNT1 variant of unknown significance. We analysed the properties of KCNT1 potassium currents and attempted to find a correlation between the changes in KCNT1 characteristics due to the mutations and severity of the neurological disorder they cause. KCNT1 mutations identified in patients with epilepsy were introduced into the full length human KCNT1 cDNA using quick-change site-directed mutagenesis protocol. Electrophysiological properties of different KCNT1 constructs were investigated using a heterologous expression system (HEK293T cells) and patch clamping. All mutations studied, except T314A, increased the amplitude of KCNT1 currents, and some mutations shifted the voltage dependence of KCNT1 open probability, increasing the proportion of channels open at the resting membrane potential. The T314A mutation did not affect KCNT1 current amplitude but abolished its voltage dependence. We observed a positive correlation between the severity of the neurological disorder and the KCNT1 channel open probability at resting membrane potential. This suggests that gain of function KCNT1 mutations cause epilepsy by increasing resting potassium conductance and suppressing the activity of inhibitory neurons. A reduction in action potential firing in inhibitory neurons due to excessively high resting potassium conductance leads to disinhibition of neural circuits, hyperexcitability and seizures.

Optimal choice of antiseizure medication: Agreement among experts and validation of a web-based decision support application.

OBJECTIVE: Optimal choice of antiseizure medication (ASM) depends on seizure type, syndrome, age, gender, comorbidities and co-medications. There are no fixed rules on how to weigh these factors; choices are subjective and experience-driven. We investigated agreement among experts in selecting ASM as monotherapy and used their prevailing choices to validate a web-based decision-support application. METHODS: Twenty-four international experts, blinded to the app, selected the optimal ASM for 25 individual patient-cases covering a wide variation of seizure types and other factors influencing ASM selection. The app ranked ASMs in order of likely appropriateness for each case. In a second step, experts rated anonymously the choices of the app. RESULTS: Of the 25 patient-cases (age 13-74 years), 13 were female, 18 (72%) had comorbidities, six (24%) were on contraceptives, and 13 (52%) had other co-medications. The median number of experts who selected the same ASM for a given case was 15 (62.5%) and interquartile range (IQR) 13-18 (54%-75%). Gwet's agreement coefficient among experts was 0.38 (95% confidence interval [CI] 0.32-0.44), corresponding to a "fair" agreement. Agreement between the app and the prevailing expert choice for each case was 0.48 (95% CI 0.29-0.67), corresponding to a "moderate" beyond chance agreement. The percent agreement between the highest ranked selections of the app and the expert selections was 73% (95% CI 64%-82%). Ninety-five percent of the experts considered that no incorrect or potentially harmful ASMs were ranked highest by the app, and most experts strongly agreed with the app's selections. SIGNIFICANCE: This app, now validated by experts, provides an objective, reproducible method for selecting ASM that accounts for relevant clinical features. It is freely available at: https://epipick.org.

A web-based algorithm to rapidly classify seizures for the purpose of drug selection.

OBJECTIVE: To develop and validate a pragmatic algorithm that classifies seizure types, to facilitate therapeutic decision-making. METHODS: Using a modified Delphi method, five experts developed a pragmatic classification of nine types of epileptic seizures or combinations of seizures that influence choice of medication, and constructed a simple algorithm, freely available on the internet. The algorithm consists of seven questions applicable to patients with seizure onset at the age of 10 years or older. Questions to screen for nonepileptic attacks were added. Junior physicians, nurses, and physician assistants applied the algorithm to consecutive patients in a multicenter prospective validation study (ClinicalTrials.gov identifier: NCT03796520). The reference standard was the seizure classification by expert epileptologists, based on all available data, including electroencephalogram (EEG), video-EEG monitoring, and neuroimaging. In addition, physicians working in underserved areas assessed the feasibility of using the web-based algorithm in their clinical setting. RESULTS: A total of 262 patients were assessed, of whom 157 had focal, 51 had generalized, and 10 had unknown onset epileptic seizures, and 44 had nonepileptic paroxysmal events. Agreement between the algorithm and the expert classification was 83.2% (95% confidence interval = 78.6%-87.8%), with an agreement coefficient (AC1) of .82 (95% confidence interval = .77-.87), indicating almost perfect agreement. Thirty-two health care professionals from 14 countries evaluated the feasibility of the web-based algorithm in their clinical setting, and found it applicable and useful for their practice (median = 6.5 on 7-point Likert scale). SIGNIFICANCE: The web-based algorithm provides an accurate classification of seizure types, which can be used for selecting antiseizure medications in adolescents and adults.

Novel congenital disorder of O-linked glycosylation caused by GALNT2 loss of function.

Congenital disorders of glycosylation are a growing group of rare genetic disorders caused by deficient protein and lipid glycosylation. Here, we report the clinical, biochemical, and molecular features of seven patients from four families with GALNT2-congenital disorder of glycosylation (GALNT2-CDG), an O-linked glycosylation disorder. GALNT2 encodes the Golgi-localized polypeptide N-acetyl-d-galactosamine-transferase 2 isoenzyme. GALNT2 is widely expressed in most cell types and directs initiation of mucin-type protein O-glycosylation. All patients showed loss of O-glycosylation of apolipoprotein C-III, a non-redundant substrate for GALNT2. Patients with GALNT2-CDG generally exhibit a syndrome characterized by global developmental delay, intellectual disability with language deficit, autistic features, behavioural abnormalities, epilepsy, chronic insomnia, white matter changes on brain MRI, dysmorphic features, decreased stature, and decreased high density lipoprotein cholesterol levels. Rodent (mouse and rat) models of GALNT2-CDG recapitulated much of the human phenotype, including poor growth and neurodevelopmental abnormalities. In behavioural studies, GALNT2-CDG mice demonstrated cerebellar motor deficits, decreased sociability, and impaired sensory integration and processing. The multisystem nature of phenotypes in patients and rodent models of GALNT2-CDG suggest that there are multiple non-redundant protein substrates of GALNT2 in various tissues, including brain, which are critical to normal growth and development.

Refining Genotypes and Phenotypes in KCNA2-Related Neurological Disorders.

Pathogenic variants in KCNA2, encoding for the voltage-gated potassium channel Kv1.2, have been identified as the cause for an evolving spectrum of neurological disorders. Affected individuals show early-onset developmental and epileptic encephalopathy, intellectual disability, and movement disorders resulting from cerebellar dysfunction. In addition, individuals with a milder course of epilepsy, complicated hereditary spastic paraplegia, and episodic ataxia have been reported. By analyzing phenotypic, functional, and genetic data from published reports and novel cases, we refine and further delineate phenotypic as well as functional subgroups of KCNA2-associated disorders. Carriers of variants, leading to complex and mixed channel dysfunction that are associated with a gain- and loss-of-potassium conductance, more often show early developmental abnormalities and an earlier onset of epilepsy compared to individuals with variants resulting in loss- or gain-of-function. We describe seven additional individuals harboring three known and the novel KCNA2 variants p.(Pro407Ala) and p.(Tyr417Cys). The location of variants reported here highlights the importance of the proline(405)-valine(406)-proline(407) (PVP) motif in transmembrane domain S6 as a mutational hotspot. A novel case of self-limited infantile seizures suggests a continuous clinical spectrum of KCNA2-related disorders. Our study provides further insights into the clinical spectrum, genotype-phenotype correlation, variability, and predicted functional impact of KCNA2 variants.

A pragmatic algorithm to select appropriate antiseizure medications in patients with epilepsy.

OBJECTIVE: Antiseizure medications (ASMs) are the first-line treatment for epilepsy. Many ASMs are available; this offers the opportunity to improve therapy by tailoring it to individual characteristics, but also increases the possibility of healthcare professionals making inappropriate treatment choices. To assist healthcare professionals, we developed a pragmatic algorithm aimed at facilitating medication selection for individuals whose epilepsy begins at age 10 years and older. METHODS: Utilizing available evidence and a Delphi panel-based consensus process, a group of epilepsy experts developed an algorithm for selection of ASMs, depending on the seizure type(s) and the presence of relevant clinical variables (age, gender, comorbidities, and comedications). The algorithm was implemented into a web-based application that was tested and improved in an iterative process. RESULTS: The algorithm categorizes ASMs deemed to be appropriate for each seizure type or combination of seizure types into three groups, with group 1 ASMs considered preferred, group 2 considered second line, and group 3 considered third line. Depending on the presence of relevant clinical variables, the ranking of individual ASMs is adjusted in the prioritization scheme to tailor recommendations to the characteristics of the individual. The algorithm is available on a web-based application at: https://epipick.org/#/. SIGNIFICANCE: The proposed algorithm is user-friendly, requires less than 2 minutes to complete, and provides the user with a range of appropriate treatment options from which to choose. This should facilitate its broad utilization and contribute to improve epilepsy management for healthcare providers who desire advice, particularly those who lack special expertise in the field.

Utility of genetic testing for therapeutic decision-making in adults with epilepsy.

OBJECTIVE: Genetic testing has become a routine part of the diagnostic workup in children with early onset epilepsies. In the present study, we sought to investigate a cohort of adult patients with epilepsy, to determinate the diagnostic yield and explore the gain of personalized treatment approaches in adult patients. METHODS: Two hundred patients (age span = 18-80 years) referred for diagnostic gene panel testing at the Danish Epilepsy Center were included. The vast majority (91%) suffered from comorbid intellectual disability. The medical records of genetically diagnosed patients were mined for data on epilepsy syndrome, cognition, treatment changes, and seizure outcome following the genetic diagnosis. RESULTS: We found a genetic diagnosis in 46 of 200 (23%) patients. SCN1A, KCNT1, and STXBP1 accounted for the greatest number of positive findings (48%). More rare genetic findings included SLC2A1, ATP6A1V, HNRNPU, MEF2C, and IRF2BPL. Gene-specific treatment changes were initiated in 11 of 46 (17%) patients (one with SLC2A1, 10 with SCN1A) following the genetic diagnosis. Ten patients improved, with seizure reduction and/or increased alertness and general well-being. SIGNIFICANCE: With this study, we show that routine diagnostic testing is highly relevant in adults with epilepsy. The diagnostic yield is similar to previously reported pediatric cohorts, and the genetic findings can be useful for therapeutic decision-making, which may lead to better seizure control, ultimately improving quality of life.