Outcomes and comorbidities of SCN1A-related seizure disorders

Quality of life in SCN1A-related seizure disorders across the lifespan

This cohort study aims to describe the evolution of disease features and health-related quality of life per life stage in Dravet syndrome and other SCN1A-related non-Dravet seizure disorders which will enable treating physicians to provide tailored care. Health-related quality of life and disease features were assessed cross-sectionally in participants with a SCN1A-related seizure disorder, categorized per age group for Dravet syndrome, and longitudinally over seven years follow-up (2015-2022). Data were collected from questionnaires, medical records, and semi-structured telephonic interviews. Health-related quality of life was measured with the Paediatric Quality of Life Inventory, proxy-reported for participants with Dravet syndrome and for participants with non-Dravet aged younger than 18 years old and self-reported for participants with non-Dravet over 18 years old. Associations between health-related quality of life and disease features were explored with multivariable regression analyses, cross-sectionally in a cohort of 115 patients with Dravet and 48 patients with generalized epilepsy with febrile seizures plus and febrile seizures (non-Dravet) and longitudinally in a cohort of 52 Dravet patients and 13 non-Dravet patients. In the cross-sectional assessment in 2022, health-related quality of life was significantly lower in Dravet syndrome, compared to non-Dravet and normative controls. Health-related quality of life in the School and Psychosocial domain was significantly higher in older Dravet age groups. A higher health-related quality of life was associated with fewer behavioural problems [β = -1.1; 95% confidence interval (CI), (-1.4 to -0.8)], independent walking (β = 8.5; 95%CI (4.2-12.8)), compared to the use of a wheelchair), and fewer symptoms of autonomic dysfunction (β = -2.1, 95%CI (-3.2 to -1.0)). Longitudinally, health-related quality of life was significantly higher seven years later in the course of disease in Dravet participants (Δ8.9 standard deviation (SD) 18.0, P < 0.05), mediated by a lower prevalence of behavioural problems (β = -1.2, 95%CI (-2.0 to -0.4)), lower seizure frequency (β = -0.1, 95%CI (-0.2 to -0.0)) and older age (β = 0.03, 95%CI (0.01-0.04)). In summary, health-related quality of life was significantly higher at older age in Dravet syndrome. This finding may reflect the benefits of an advanced care strategy in recent years and a ceiling of severity of disease symptoms, possibly resulting in an increased wellbeing of parents and patients. The strong association with behavioural problems reinforces the need to incorporate a multidisciplinary approach, tailored to the age-specific needs of this patient group, into standard care.

Insights into clinical phenotypes and treatment responses in a Small cohort of Taiwanese patients with SCN1A variants: A Preliminary study

BACKGROUND

SCN1A channelopathy is the most well-known cause for epileptic encephalopathies and contributes to a wide phenotypic spectrum. The variable expressivity is troublesome for the interpretation of clinical significance and prognoses. To investigate the clinical manifestations, medications and outcomes of patients with SCN1A channelopathies, we conducted this observation retrospective study in Taiwan.

METHODS

A cohort consisting of 16 patients (5 males and 11 females) from multiple centers with identified SCN1A variants was investigated and phenotypically relevant factors were recorded. The variants were identified using NGS and confirmed by Sanger sequencing. A panel of 90 epileptic-related genes was used to identify SCN1A variants and to evaluate some of the potential SCN1A modifier genes.

RESULTS

The mean age of seizure onset was 10.4 months. Twelve of the sixteen patients (75%) had different degrees of neurocognitive sequela and psychobehavioral comorbidity in our cohort. Cognitive impairment was noted in all ten patients with Dravet syndrome (DS) and in two of the patients with non-DS phenotypes. A lower response rate to medications was also noted in patients with DS. Notably, a medication-specific tendency towards valproic acid (VPA), clobazam (CLB), and levetiracetam (LEV) was observed, revealing the effective pharmacotherapies for SCN1A-related seizures. An asymptomatic carrier with a reported pathogenic SCN1A variant was reviewed along with her monozygotic twin sister with DS. Nine novel SCN1A mutations are herein reported, eight of which being classified as pathogenic.

CONCLUSION

Our study revealed unfavorable outcomes for patients with SCN1A variants. Some patients with SCN1A channelopathy showed specific responsiveness to the pharmacotherapies previously either recommended or contraindicated for these patients. Our study also expands the genotype and provides valuable prognostic insights in patients with SCN1A channelopathy.

Understanding neurodevelopmental trajectories and behavioral profiles in SCN1A-related epilepsy syndromes

BACKGROUND

A pathogenic variant in SCN1A can result in a spectrum of phenotypes, including Dravet syndrome (DS) and genetic epilepsy with febrile seizures plus (GEFS + ) syndrome. Dravet syndrome (DS) is associated with refractory seizures, developmental delay, intellectual disability (ID), motor impairment, and challenging behavior(1,2). GEFS + is a less severe phenotype in which cognition is often normal and seizures are less severe. Challenging behavior largely affects quality of life of patients and their families. This study describes the profile and course of the behavioral phenotype in patients with SCN1A-related epilepsy syndromes, explores correlations between behavioral difficulties and potential risk factors.

METHODS

Data were collected from questionnaires, medical records, and semi-structured interviews. Behavior difficulties were measured using the Adult/Child Behavior Checklist (C/ABCL) and Adult self-report (ASR). Other questionnaires included the Pediatric Quality of Life Inventory (PedsQL), the Functional Mobility Scale (FMS) and the Sleep Behavior Questionnaire by Simonds & Parraga (SQ-SP). To determine differences in behavioral difficulties longitudinally, paired T-tests were used. Pearson correlation and Spearman rank test were used in correlation analyses and multivariable regression analyses were employed to identify potential risk factors.

RESULTS

A cohort of 147 participants, including 107 participants with DS and 40 with genetic epilepsy with febrile seizures plus (GEFS + ), was evaluated. Forty-six DS participants (43.0 %) and three GEFS + participants (7.5 %) showed behavioral problems in the clinical range on the A/CBCL total problems scale. The behavioral profile in DS exists out of withdrawn behavior, aggressive behavior, and attention problems. In DS patients, sleep disturbances (β = 1.15, p < 0.001) and a lower age (β = -0.21, p = 0.001) were significantly associated with behavioral difficulties. Between 2015 and 2022, behavioral difficulties significantly decreased with age (t = -2.24, CI = -6.10 - -0.15, p = 0.04) in DS participants aging from adolescence into adulthood. A decrease in intellectual functioning (β = 3.37, p = 0.02) and using less antiseizure medications in 2022 than in 2015, (β = -1.96, p = 0.04), were identified as possible risk factors for developing (more) behavioral difficulties.

CONCLUSIONS

These findings suggest that, in addition to epilepsy, behavioral difficulties are a core feature of the DS phenotype. Behavioral problems require personalized management and treatment strategies. Further research is needed to identify effective interventions.

Severe communication delays are independent of seizure burden and persist despite contemporary treatments in SCN1A+ Dravet syndrome: Insights from the ENVISION natural history study

OBJECTIVE

Dravet syndrome (DS) is a developmental and epileptic encephalopathy characterized by high seizure burden, treatment-resistant epilepsy, and developmental stagnation. Family members rate communication deficits among the most impactful disease manifestations. We evaluated seizure burden and language/communication development in children with DS.

METHODS

ENVISION was a prospective, observational study evaluating children with DS associated with SCN1A pathogenic variants (SCN1A+ DS) enrolled at age ≤5 years. Seizure burden and antiseizure medications were assessed every 3 months and communication and language every 6 months with the Bayley Scales of Infant and Toddler Development 3rd edition and the parent-reported Vineland Adaptive Behavior Scales 3rd edition. We report data from the first year of observation, including analyses stratified by age at Baseline: 0:6-2:0 years:months (Y:M; youngest), 2:1-3:6 Y:M (middle), and 3:7-5:0 Y:M (oldest).

RESULTS

Between December 2020 and March 2023, 58 children with DS enrolled at 16 sites internationally. Median follow-up was 17.5 months (range = .0-24.0), with 54 of 58 (93.1%) followed for at least 6 months and 51 of 58 (87.9%) for 12 months. Monthly countable seizure frequency (MCSF) increased with age (median [minimum-maximum] = 1.0 in the youngest [1.0-70.0] and middle [1.0-242.0] age groups and 4.5 [.0-2647.0] in the oldest age group), and remained high, despite use of currently approved antiseizure medications. Language/communication delays were observed early, and developmental stagnation occurred after age 2 years with both instruments. In predictive modeling, chronologic age was the only significant covariate of seizure frequency (effect size = .52, p = .024). MCSF, number of antiseizure medications, age at first seizure, and convulsive status epilepticus were not predictors of language/communication raw scores.

SIGNIFICANCE

In infants and young children with SCN1A+ DS, language/communication delay and stagnation were independent of seizure burden. Our findings emphasize that the optimal therapeutic window to prevent language/communication delay is before 3 years of age.

Long-term predictors of developmental outcome and disease burden in SCN1A-positive Dravet syndrome

Dravet syndrome is a severe infantile onset developmental and epileptic encephalopathy associated with mutations in the sodium channel alpha 1 subunit gene SCN1A. Prospective data on long-term developmental and clinical outcomes are limited; this study seeks to evaluate the clinical course of Dravet syndrome over a 10-year period and identify predictors of developmental outcome. SCN1A mutation-positive Dravet syndrome patients were prospectively followed up in the UK from 2010 to 2020. Caregivers completed structured questionnaires on clinical features and disease burden; the Epilepsy & Learning Disability Quality of Life Questionnaire, the Adaptive Behavioural Assessment System-3 and the Sleep Disturbance Scale for Children. Sixty-eight of 113 caregivers (60%) returned posted questionnaires. Developmental outcome worsened at follow-up (4.45 [SD 0.65], profound cognitive impairment) compared to baseline (2.9 [SD 1.1], moderate cognitive impairment, P < 0.001), whereas epilepsy severity appeared less severe at 10-year follow-up (P = 0.042). Comorbidities were more apparent at 10-year outcome including an increase in autistic features (77% [48/62] versus 30% [17/57], χ2 = 19.9, P < 0.001), behavioural problems (81% [46/57] versus 38% [23/60], χ2 = 14.1, P < 0.001) and motor/mobility problems (80% [51/64] versus 41% [24/59], χ2 = 16.9, P < 0.001). Subgroup analysis demonstrated a more significant rise in comorbidities in younger compared to older patients. Predictors of worse long-term developmental outcome included poorer baseline language ability (P < 0.001), more severe baseline epilepsy severity (P = 0.003) and a worse SCN1A genetic score (P = 0.027). Sudden unexpected death in epilepsy had not been discussed with a medical professional in 35% (24/68) of participants. Over 90% of caregivers reported a negative impact on their own health and career opportunities. Our study identifies important predictors and potential biomarkers of developmental outcome in Dravet syndrome and emphasizes the significant caregiver burden of illness. The negative impact of epilepsy severity at baseline on long-term developmental outcomes highlights the importance of implementing early and focused therapies whilst the potential impact of newer anti-seizure medications requires further study.

Dravet syndrome: A systematic literature review of the illness burden

We performed a systematic literature review and narrative synthesis according to a pre-registered protocol (Prospero: CRD42022376561) to identify the evidence associated with the burden of illness in Dravet syndrome (DS), a developmental and epileptic encephalopathy characterized by drug-resistant epilepsy with neurocognitive and neurobehavioral impairment. We searched MEDLINE, Embase, and APA PsychInfo, Cochrane's database of systematic reviews, and Epistemonikos from inception to June 2022. Non-interventional studies reporting on epidemiology (incidence, prevalence, and mortality), patient and caregiver health-related quality of life (HRQoL), direct and indirect costs and healthcare resource utilization were eligible. Two reviewers independently carried out the screening. Pre-specified data were extracted and a narrative synthesis was conducted. Overall, 49 studies met the inclusion criteria. The incidence varied from 1:15 400-1:40 900, and the prevalence varied from 1.5 per 100 000 to 6.5 per 100 000. Mortality was reported in 3.7%-20.8% of DS patients, most commonly due to sudden unexpected death in epilepsy and status epilepticus. Patient HRQoL, assessed by caregivers, was lower than in non-DS epilepsy patients; mean scores (0 [worst] to 100/1 [best]) were 62.1 for the Kiddy KINDL/Kid-KINDL, 46.5-54.7 for the PedsQL and 0.42 for the EQ-5D-5L. Caregivers, especially mothers, were severely affected, with impacts on their time, energy, sleep, career, and finances, while siblings were also affected. Symptoms of depression were reported in 47%-70% of caregivers. Mean total direct costs were high across all studies, ranging from $11 048 to $77 914 per patient per year (PPPY), with inpatient admissions being a key cost driver across most studies. Mean costs related to lost productivity were only reported in three publications, ranging from approximately $19 000 to $20 000 PPPY ($17 596 for mothers vs $1564 for fathers). High seizure burden was associated with higher resource utilization, costs and poorer HRQoL. The burden of DS on patients, caregivers, the healthcare system, and society is profound, reflecting the severe nature of the syndrome. Future studies will be able to assess the impact that newly approved therapies have on reducing the burden of DS.

Functional mobility in children and young adults with Dravet syndrome

AIM

This cohort study aimed to describe functional mobility in Dravet syndrome, a developmental and epileptic encephalopathy.

METHOD

Functional mobility was assessed in individuals (aged 3-25 years), diagnosed with Dravet syndrome, using the Functional Mobility Scale (FMS), Mobility Questionnaire 28 (MobQues28), and estimated walking distance. Secondary outcome variables were Gait Profile Score (GPS), walking velocity, age at independent walking, intellectual disability, seizure frequency, genetic variant type, and body mass index (BMI).

RESULTS

Forty participants aged 3 years to 24 years 2 months (mean = 12 years 2 months) had a median MobQues28 of 79%, median scores of 5, 5, and 4 for the FMS 5 m, 50 m, and 500 m and a median estimated walking distance of 1 km to 3 km. Most difficulties were seen in walking up and down the stairs, walking over obstacles, kicking a ball, and running. MobQues28 scores showed a significant decrease (-6.6%, p = 0.016) in the age category of young adults (≥18 years). After correcting for age, MobQues28 was correlated to age at independent walking (-0.485, p = 0.002), GPS (-0.460, p = 0.003), and walking velocity (0.334, p = 0.038). Analysis of variance showed a significant effect of intellectual disability and BMI on MobQues28 (p = 0.029, p = 0.049). No effect of seizure frequency or genetic variant was found (p = 0.579, p = 0.337).

INTERPRETATION

Functional mobility limitations were observed mainly in dual tasks and activities requiring stability, with limitations increasing from the age of 18 years. Age at independent walking, gait impairments, intellectual disability, and BMI can impact functional mobility in Dravet syndrome.

WHAT THIS PAPER ADDS

Most limitations were seen in dual task activities and activities that required more stability. Deterioration in functional mobility occurred in young adults. The more gait impairments, the more functional mobility limitations. Age at independent walking, intellectual disability, and body mass index can impact functional mobility.

Widespread genomic influences on phenotype in Dravet syndrome, a 'monogenic' condition

Dravet syndrome is an archetypal rare severe epilepsy, considered 'monogenic', typically caused by loss-of-function SCN1A variants. Despite a recognizable core phenotype, its marked phenotypic heterogeneity is incompletely explained by differences in the causal SCN1A variant or clinical factors. In 34 adults with SCN1A-related Dravet syndrome, we show additional genomic variation beyond SCN1A contributes to phenotype and its diversity, with an excess of rare variants in epilepsy-related genes as a set and examples of blended phenotypes, including one individual with an ultra-rare DEPDC5 variant and focal cortical dysplasia. The polygenic risk score for intelligence was lower, and for longevity, higher, in Dravet syndrome than in epilepsy controls. The causal, major-effect, SCN1A variant may need to act against a broadly compromised genomic background to generate the full Dravet syndrome phenotype, whilst genomic resilience may help to ameliorate the risk of premature mortality in adult Dravet syndrome survivors.

Gastrointestinal and eating problems in SCN1A-related seizure disorders

OBJECTIVE

Our study aimed to describe the prevalence and characteristics of gastrointestinal and eating problems in Dravet syndrome (DS) and other SCN1A-related seizure disorders and to determine the association between the occurrence of gastrointestinal and eating problems and core features of DS.

METHODS

Gastrointestinal and eating problems were assessed with a questionnaire in a Dutch cohort of participants with an SCN1A-related seizure disorder. Associations between the number of gastrointestinal and eating problems and core features of DS, seizure severity, level of intellectual disability, impaired mobility, behavioral problems, and use of anti-seizure medication, were explored by multivariate ordinal regression analyses. Symptoms were divided into the categories dysphagia-related, behavioral, and gastrointestinal, and were assessed separately.

RESULTS

One hundred sixty-nine participants with an SCN1A-related seizure disorder, of whom 118 (69.8%) with DS and 51 (30.2%) with Generalized Epilepsy with Febrile Seizures Plus / Febrile Seizures (GEFS+/FS), the non-DS phenotype, were evaluated. Gastrointestinal and eating problems were highly prevalent in DS participants, 50.8% had more than three symptoms compared to 3.9% of non-DS participants. Of participants with DS, 17.8% were fully or partly fed by a gastric tube. Within the three different symptom categories, the most prevalent dysphagia-related symptom was drooling (60.7%), distraction during mealtimes (61.4%) the most prevalent behavioral symptom, and constipation and loss of appetite (both 50.4%) the most prevalent gastrointestinal symptoms. DS participants who use a wheelchair (odds ratio (OR) 4.9 95%CI (1.9-12.8) compared to walking without aid), who use ≥3 anti-seizure medications (ASM) (OR 5.9 95%CI (1.9-18.2) compared to <3 ASM) and who have behavioral problems (OR 3.0 95%CI (1.1-8.1) compared to no behavioral problems) had more gastrointestinal and eating problems.

CONCLUSION

Gastrointestinal and eating problems are frequently reported symptoms in DS. Distinguishing between symptom categories will lead to tailored management of patients at risk, will improve early detection, and enable a timely referral to a dietitian, behavioral expert, and/or speech therapist, ultimately aiming to improve the quality of life of both patients and caregivers.

Autonomic dysfunction in epilepsy mouse models with implications for SUDEP research

Epilepsy has a high prevalence and can severely impair quality of life and increase the risk of premature death. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in drug-resistant epilepsy and most often results from respiratory and cardiac impairments due to brainstem dysfunction. Epileptic activity can spread widely, influencing neuronal activity in regions outside the epileptic network. The brainstem controls cardiorespiratory activity and arousal and reciprocally connects to cortical, diencephalic, and spinal cord areas. Epileptic activity can propagate trans-synaptically or via spreading depression (SD) to alter brainstem functions and cause cardiorespiratory dysfunction. The mechanisms by which seizures propagate to or otherwise impair brainstem function and trigger the cascading effects that cause SUDEP are poorly understood. We review insights from mouse models combined with new techniques to understand the pathophysiology of epilepsy and SUDEP. These techniques include in vivo, ex vivo, invasive and non-invasive methods in anesthetized and awake mice. Optogenetics combined with electrophysiological and optical manipulation and recording methods offer unique opportunities to study neuronal mechanisms under normal conditions, during and after non-fatal seizures, and in SUDEP. These combined approaches can advance our understanding of brainstem pathophysiology associated with seizures and SUDEP and may suggest strategies to prevent SUDEP.

Challenging behavior in children and adolescents with Dravet syndrome: Exploring the lived experiences of parents

BACKGROUND

Dravet syndrome (DS) is a monogenic syndrome associated with SCN1A mutations in the majority of patients and characterized by devastating epilepsy, that may be life-threatening. Aside from refractory seizures, core symptoms of DS include behavioral difficulties, developmental delay, cognitive impairment, and motor dysfunction. Previous DS research has mainly focused on epileptic seizures and pharmacological management and less on behavioral difficulties. This study aims to explore the lived experience of parents supporting a child with DS, with a focus on behavioral aspects.

METHODS

We performed a qualitative study using focus groups and following the consolidated criteria for reporting qualitative research (COREQ) guidelines. We organized three focus groups with parents of children and adults with DS and used a pre-defined topic list of open questions, similar for each focus group to ensure comparability. The focus groups were video recorded, transcribed, and anonymized. Data were analyzed using an iterative coding process where codes were sorted into themes. Differences in coding among the researchers were discussed until a consensus was reached.

RESULTS

In total, twenty parents (mothers only) participated in the study. The age of children with DS ranged between 3 to 22 years with a mean age of 11.8 years. A range of behavioral difficulties emerged from the thematic analysis. Overall, the most commonly mentioned behavioral difficulties were aggression, dangerous behavior, impulsivity, hyperactivity, routinized and compulsive habits. Our results showed different behavior per age group, with more externalizing behaviors such as aggression and impulsivity in children aged 3-13 years; and more internalizing behavior such as routinized and compulsive habits in adolescents and young adults (14-22 years). This results in a different kind of support these families need and should be acknowledged when in consult with a healthcare professional. Parents reported that challenging behavior was a source of stress and impacted negatively on their family's quality of life. Parents reported feeling alone in their search for solutions, and many explored options outside the traditional medical context.

CONCLUSION

Our results suggest that the challenging behavior associated with DS leads to a huge burden of care. Healthcare professionals working with DS patients may need to develop shared decision-making strategies that take into account challenging behavior.

The clinical, economic, and humanistic burden of Dravet syndrome - A systematic literature review

Dravet syndrome (DS) is a developmental and epileptic encephalopathy with evolving disease course as individuals age. In recent years, the treatment landscape of DS has changed considerably, and a comprehensive systematic review of the contemporary literature is lacking. Here we synthesized published evidence on the occurrence of clinical impacts by age, the economic and humanistic (health-related quality-of-life [HRQoL]) burden, and health state utility. We provide an evidence-based, contemporary visualization of the clinical manifestations, highlighting that DS is not limited to seizures; non-seizure manifestations appear early in life and increase over time, contributing significantly to the economic and humanistic burden of disease. The primary drivers of HRQoL in DS include seizure severity, cognition, and motor and behavioral problems; in turn, these directly affect caregivers through the extent of assistance required and consequent impact on activities of daily living. Unsurprisingly, costs are driven by seizure-related events, hospitalizations, and in-home medical care visits. This systematic review highlights a paucity of longitudinal data; most studies meeting inclusion criteria were cross-sectional or had short follow-up. Nonetheless, available data illustrate the substantial impact on individuals, their families, and healthcare systems and establish the need for novel therapies to address the complex spectrum of DS manifestations.

Guidance on Dravet syndrome from infant to adult care: Road map for treatment planning in Europe

Dravet syndrome (DS) is a severe, rare, and complex developmental and epileptic encephalopathy affecting 1 in 16 000 live births and characterized by a drug‐resistant epilepsy, cognitive, psychomotor, and language impairment, and behavioral disorders. Evidence suggests that optimal treatment of seizures in DS may improve outcomes, even though neurodevelopmental impairments are the likely result of both the underlying genetic variant and the epilepsy. We present an updated guideline for DS diagnosis and treatment, taking into consideration care of the adult patient and nonpharmaceutical therapeutic options for this disease. This up‐to‐date guideline, which is based on an extensive review of the literature and culminates with a new treatment algorithm for DS, is a European consensus developed through a survey involving 29 European clinical experts in DS. This guideline will serve professionals in their clinical practice and, as a consequence, will benefit DS patients and their families.

DRAVET ENGAGE. Parent caregivers of children with Dravet syndrome: Perspectives, needs, and opportunities for clinical research

Dravet syndrome (DS) is an intractable developmental and epileptic encephalopathy significantly impacting affected children and their families. A novel, one-time, adeno-associated virus (AAV)-mediated gene regulation therapy was designed to treat the underlying cause of DS, potentially improving the full spectrum of DS manifestations. To ensure the first-in-human clinical trial addresses meaningful outcomes for patients and families, we examined their perspectives, priorities, goals, and desired outcomes in the design phase through a mixed methods approach (quantitative and qualitative). We conducted a non-identifiable parent caregiver survey, shared through a patient advocacy organization (n = 36 parents; children age ≤6 years). Parents were also engaged via three group discussions (n = 10; children age 2-20 years) and optional follow-up in-depth individual interviews (n = 6). Qualitative data analysis followed an inductive interpretive process, and qualitative researchers conducted a thematic analysis with a narrative approach. Survey results revealed most children (94%) were diagnosed by age 1, with onset of seizures at mean age 6.2 months and other DS manifestations before 2 years. The most desired disease aspects to address with potential new disease-modifying therapies were severe seizures (ranked by 92% of caregivers) and communication issues (development, expressive, receptive; 72-83%). Qualitative results showed the need for trial outcomes that recognize the impact of DS on the whole family. Parents eventually hope for trials including children of all ages and were both excited about the potential positive impact of a one-time disease-modifying therapy and mindful of potential long-term implications. Participants reflected on the details and risks of a clinical trial design (e.g., sham procedures) and described the different factors that relate to their decision to participate in a trial. Their main aspirations were to stop neurodevelopmental stagnation, to reduce seizures, and to reduce the impact on their families' wellbeing. To our knowledge, this is the first study within a patient-oriented research framework that specifically explored parents' needs and perceptions regarding clinical trials of a potential disease-modifying therapy for children with a severe, developmental disease, such as DS.

[Early identification and diagnosis of epilepsy related to fever sensitivity]

Febrile seizures are the most common nervous system disease in childhood, and most children have a good prognosis. However, some epilepsy cases are easily induced by fever and are characterized by "fever sensitivity", and it is difficult to differentiate such cases from febrile seizures. Epilepsy related to fever sensitivity includes hereditary epilepsy with febrile seizures plus, Dravet syndrome, and PCDH19 gene-related epilepsy. This article mainly describes the clinical manifestations of these three types of epilepsy and summarizes their clinical features in the early stage of disease onset, so as to achieve early identification, early diagnosis, and early intervention to improve prognosis.

Dravet Syndrome: Novel Approaches for the Most Common Genetic Epilepsy

Dravet syndrome (DS) is a severe developmental and epileptic encephalopathy that is mainly associated with variants in SCN1A. While drug-resistant epilepsy is the most notable feature of this syndrome, numerous symptoms are present that have significant impact on patients' quality of life. In spite of novel, third-generation anti-seizure treatment options becoming available over the last several years, seizure freedom is often not attained and non-seizure symptoms remain. Precision medicine now offers realistic hope for seizure freedom in DS patients, with several approaches demonstrating preclinical success. Therapeutic approaches such as antisense oligonucleotides (ASO) and adeno-associated virus (AAV)-delivered gene modulation have expanded the potential treatment options for DS, with some of these approaches now transitioning to clinical trials. Several of these treatments may risk the exacerbation of gain-of-function variants and may not be reversible, therefore emphasizing the need for functional testing of new pathogenic variants. The current absence of treatments that address the overall disease, in addition to seizures, exposes the urgent need for reliable, valid measures of the entire complement of symptoms as outcome measures to truly know the impact of treatments on DS. Additionally, with so many treatment options on the horizon, there will be a need to understand how to select appropriate patients for each treatment, whether treatments are complementary or adverse to each other, and long-term risks of the treatment. Nevertheless, precision therapeutics hold tremendous potential to provide long-lasting seizure freedom and even complete cures for this devastating disease.

Gabra2 is a genetic modifier of Dravet syndrome in mice

Pathogenic variants in epilepsy genes result in a spectrum of clinical severity. One source of phenotypic heterogeneity is modifier genes that affect expressivity of a primary pathogenic variant. Mouse epilepsy models also display varying degrees of clinical severity on different genetic backgrounds. Mice with heterozygous deletion of Scn1a (Scn1a^+/−) model Dravet syndrome, a severe epilepsy most often caused by SCN1A haploinsufficiency. Scn1a^+/− mice recapitulate features of Dravet syndrome, including spontaneous seizures, sudden death, and cognitive/behavioral deficits. Scn1a^+/− mice maintained on the 129S6/SvEvTac (129) strain have normal lifespan and no spontaneous seizures. In contrast, admixture with C57BL/6J (B6) results in epilepsy and premature lethality. We previously mapped Dravet Survival Modifier loci (Dsm1-Dsm5) responsible for strain-dependent differences in survival. Gabra2, encoding the GABA_A α2 subunit, was nominated as a candidate modifier at Dsm1. Direct measurement of GABA_A receptors found lower abundance of α2-containing receptors in hippocampal synapses of B6 mice relative to 129. We also identified a B6-specific single nucleotide deletion within Gabra2 that lowers mRNA and protein by nearly 50%. Repair of this deletion reestablished normal levels of Gabra2 expression. In this study, we used B6 mice with a repaired Gabra2 allele to evaluate Gabra2 as a genetic modifier of severity in Scn1a^+/− mice. Gabra2 repair restored transcript and protein expression, increased abundance of α2-containing GABA_A receptors in hippocampal synapses, and rescued epilepsy phenotypes of Scn1a^+/− mice. These findings validate Gabra2 as a genetic modifier of Dravet syndrome, and support enhancing function of α₂-containing GABA_A receptors as treatment strategy for Dravet syndrome.

Neocortex- and hippocampus-specific deletion of Gabrg2 causes temperature-dependent seizures in mice

Mutations in the GABRG2 gene encoding the γ-aminobutyric acid (GABA) A receptor gamma 2 subunit are associated with genetic epilepsy with febrile seizures plus, febrile seizures plus, febrile seizures, and other symptoms of epilepsy. However, the mechanisms underlying Gabrg2-mediated febrile seizures are poorly understood. Here, we used the Cre/loxP system to generate conditional knockout (CKO) mice with deficient Gabrg2 in the hippocampus and neocortex. Heterozygous CKO mice (Gabrg2^fl/wtCre⁺) exhibited temperature-dependent myoclonic jerks, generalised tonic-clonic seizures, increased anxiety-like symptoms, and a predisposition to induce seizures. Cortical electroencephalography showed the hyperexcitability in response to temperature elevation in Gabrg2^fl/wtCre⁺ mice, but not in wild-type mice. Gabrg2^fl/wtCre⁺ mice exhibited spontaneous seizures and susceptibility to temperature-induced seizures. Loss of neurons were observed in cortical layers V-VI and hippocampus of Gabrg2^fl/wtCre⁺ mice. Furthermore, the latency of temperature- or pentylenetetrazol-induced seizures were significantly decreased in Gabrg2^fl/wtCre⁺ mice compared with wild-type mice. In summary, Gabrg2^fl/wtCre⁺ mice with Gabrg2 deletion in the neocortex and hippocampus reproduce many features of febrile seizures and therefore provide a novel model to further understand this syndrome at the cellular and molecular level.

Phenotypic homogeneity in childhood epilepsies evolves in gene-specific patterns across 3251 patient-years of clinical data

While genetic studies of epilepsies can be performed in thousands of individuals, phenotyping remains a manual, non-scalable task. A particular challenge is capturing the evolution of complex phenotypes with age. Here, we present a novel approach, applying phenotypic similarity analysis to a total of 3251 patient-years of longitudinal electronic medical record data from a previously reported cohort of 658 individuals with genetic epilepsies. After mapping clinical data to the Human Phenotype Ontology, we determined the phenotypic similarity of individuals sharing each genetic etiology within each 3-month age interval from birth up to a maximum age of 25 years. 140 of 600 (23%) of all 27 genes and 3-month age intervals with sufficient data for calculation of phenotypic similarity were significantly higher than expect by chance. 11 of 27 genetic etiologies had significant overall phenotypic similarity trajectories. These do not simply reflect strong statistical associations with single phenotypic features but appear to emerge from complex clinical constellations of features that may not be strongly associated individually. As an attempt to reconstruct the cognitive framework of syndrome recognition in clinical practice, longitudinal phenotypic similarity analysis extends the traditional phenotyping approach by utilizing data from electronic medical records at a scale that is far beyond the capabilities of manual phenotyping. Delineation of how the phenotypic homogeneity of genetic epilepsies varies with age could improve the phenotypic classification of these disorders, the accuracy of prognostic counseling, and by providing historical control data, the design and interpretation of precision clinical trials in rare diseases.

Dravet syndrome and Dravet syndrome-like phenotype: a systematic review of the SCN1A and PCDH19 variants

Dravet syndrome (DS) is a rare and severe epileptic syndrome of childhood with prevalence between 1/22,000 and 1/49,900 of live births. Approximately 80% of patients with this syndrome present SCN1A pathogenic variants, which encodes an alpha subunit of a neural voltage-dependent sodium channel. There is a correlation between PCDH19 pathogenic variants, encodes the protocadherin 19, and a similar disease to DS known as DS-like phenotype. The present review aims to clarify the differences between DS and DS-like phenotype according to the SCN1A and PCDH19 variants. A systematic review was conducted in PubMed and Virtual Health Library (VHL) databases, using "Dravet Syndrome" and "Severe Myoclonic Epilepsy in Infancy (SMEI)" search words, selecting cohort of studies published in journal with impact factor of two or greater. The systematic review was according to the Preferred Reporting Items for Systematic Review and Meta-Analysis recommendations. Nineteen studies were included in the present review, and a significant proportion of patients with DS-carrying SCN1A was greater than patients with DS-like phenotype-harboring PCDH19 variants (76.6% versus 23.4%). When clinical and genetic data were correlated, autism was predominantly observed in patients with DS-like-carrying PCDH19 variants compared to SCN1A variant carriers (62.5% versus 37.5%, respectively, P-value = 0.044, P-value corrected = 0.198). In addition, it was noticed a significant predisposition to hyperthermia during epilepsy crisis in individuals carrying PCDH19 variants (P-value = 0.003; P-value corrected = 0.027). The present review is the first to point out differences between the DS and DS-like phenotype according to the SCN1A and PCDH19 variants.

Independent walking and cognitive development in preschool children with Dravet syndrome

AIM

To investigate the relation between cognitive and motor development in preschool aged children with Dravet syndrome, in particular between the age of independent walking and cognitive development.

METHOD

Results of cognitive and motor developmental assessments and the age of independent walking were retrieved retrospectively from the medical records of 33 children (17 males, 16 females; mean age at last evaluation 33.2mo, SD 8.2mo, range 9-48mo) diagnosed with Dravet syndrome. Cognitive and motor developmental age, derived from the Bayley Scales of Infant Development or through standardized neurodevelopmental assessment, were converted into cognitive and motor developmental quotients. Multiple test scores per child were included.

RESULTS

A strong positive relation was found between cognitive and motor developmental quotient (Pearson r=0.854; p<0.001) in 20 children (slope=0.75; 95% CI: 0.54-0.95). A later age of independent walking was associated with a lower cognitive developmental quotient (28 children; p<0.001; slope=-1.01; 95% CI: -1.53 to -0.49). A higher cognitive developmental quotient was seen in children with an age at testing younger than 24 months. The cognitive developmental quotient of children with a delay in independent walking (>17.6mo) was significantly lower than those without a delay (p=0.006).

INTERPRETATION

A strong relation exists between cognitive and motor development. Furthermore, the age of independent walking might be an important indicator of the development of children with Dravet syndrome.

WHAT THIS PAPER ADDS

Cognitive and motor development are strongly related in children with Dravet syndrome. Later age of independent walking is associated with worse cognitive development in children with Dravet syndrome.

Cognitive performance and behavior across idiopathic/genetic epilepsies in children and adolescents

We investigated the cognitive and behavioral profile of three distinct groups of epilepsies with a genetic background for intergroup differences: (1) idiopathic/genetic generalized epilepsies (IGE/GGE group); (2) idiopathic focal epilepsies (IFE group); and (3) epilepsies with proven or strongly suggested monogenic or structural/numeric chromosomal etiology (genetic epilepsies, GE group). Cognitive (total IQ and subcategories) and behavioral parameters (CBCL) were assessed at the tertiary epilepsy center of the University of Munich (Germany). We used ANOVA with post-hoc Bonferroni-correction to explore significant mean differences and Fisher’s exact test for significant proportional differences of intelligence impairment and behavioral problems. 126 (56 IGE/GGE, 26 IFE, 44 GE) patients were available. Total IQ was 89.0 ± 15.9 (95% CI 84.5–93.4) for IGE/GGE, 94.8 ± 18.1 (95% CI 87.3–102.3) for IFE and 76.4 ± 22.4 (95% CI 67.6–85.3) for GE (p = 0.001). The same trend was significant for all but one IQ subcategory. The rate of patients with an intelligence impairment (total IQ < 70) was higher for GE (40%) than for IGE/GGE (14%) and for IFE (7%) patients (p = 0.033). There were no significant differences between groups for behavior scores and behavioral problems. This study shows that the current ILAE classification of epilepsies with genetic etiology creates a heterogeneous group of patients with respect to cognitive performance but not behavior. These findings may help in further delineating epilepsies as regards cognitive performance, notwithstanding their closely related etiological classification.

Cognitive, behavioral, and social functioning in children and adults with Dravet syndrome

AIM

The objective of the study was to delineate the cognitive, behavioral, psychological, and social functioning of individuals with Dravet syndrome.

METHOD

Cognitive, behavioral, and social functioning were assessed in patients with Dravet syndrome by comprehensive, age-appropriate standardized neuropsychological testing. Primary caregivers completed standardized measures regarding participants' behavior, psychological status, adaptive functioning, and social skills, including their involvement with intervention services.

RESULTS

The cohort comprised 45 patients, aged 2-30 years. Intellectual functioning ranged from average intellect to profound intellectual disability, with a decrease in cognitive and adaptive functioning with age. Only 6 children were able to complete the entire neuropsychological battery and showed a range of cognitive profiles. Five of 6 participants scored within the average range on Affect Recognition and 5/6 on Motor Free Visual Perception tests. Twenty-one (58%) participants had deficits in social skills and 18/27 (67%) in social communication, with 10 participants, who did not yet have a diagnosis of autism spectrum disorder (ASD), screening positive for social communication deficits. Behavioral problems were frequently reported, with attention problems in 24 (65%) and atypicality in 25 (70%). Despite this, parents reported that psychological services were the least utilized health interventions.

CONCLUSIONS

Cognitive functioning varies markedly in individuals with Dravet syndrome, with some patients demonstrating global impairment while others have a discordant neuropsychological profile. Behavioral, psychological, social problems, and ASD are common. Social deficits should be reviewed to identify those who warrant ASD assessment. Early identification of behavioral and psychological disorders and targeted use of psychological intervention are essential components of holistic care in Dravet syndrome.

Semantic Similarity Analysis Reveals Robust Gene-Disease Relationships in Developmental and Epileptic Encephalopathies

More than 100 genetic etiologies have been identified in developmental and epileptic encephalopathies (DEEs), but correlating genetic findings with clinical features at scale has remained a hurdle because of a lack of frameworks for analyzing heterogenous clinical data. Here, we analyzed 31,742 Human Phenotype Ontology (HPO) terms in 846 individuals with existing whole-exome trio data and assessed associated clinical features and phenotypic relatedness by using HPO-based semantic similarity analysis for individuals with de novo variants in the same gene. Gene-specific phenotypic signatures included associations of SCN1A with “complex febrile seizures” (HP: 0011172; p = 2.1 × 10⁻⁵) and “focal clonic seizures” (HP: 0002266; p = 8.9 × 10⁻⁶), STXBP1 with “absent speech” (HP: 0001344; p = 1.3 × 10⁻¹¹), and SLC6A1 with “EEG with generalized slow activity” (HP: 0010845; p = 0.018). Of 41 genes with de novo variants in two or more individuals, 11 genes showed significant phenotypic similarity, including SCN1A (n = 16, p < 0.0001), STXBP1 (n = 14, p = 0.0021), and KCNB1 (n = 6, p = 0.011). Including genetic and phenotypic data of control subjects increased phenotypic similarity for all genetic etiologies, whereas the probability of observing de novo variants decreased, emphasizing the conceptual differences between semantic similarity analysis and approaches based on the expected number of de novo events. We demonstrate that HPO-based phenotype analysis captures unique profiles for distinct genetic etiologies, reflecting the breadth of the phenotypic spectrum in genetic epilepsies. Semantic similarity can be used to generate statistical evidence for disease causation analogous to the traditional approach of primarily defining disease entities through similar clinical features.

Intellectual functioning and behavior in Dravet syndrome: A systematic review

BACKGROUND

Dravet syndrome (DS) is a developmental and epileptic encephalopathy with onset in the first year of life. At onset, the child displays normal development, but during the second year of life, stagnation/slowing of neurodevelopment is seen. In addition to difficulties with intellectual development, many children display behavioral problems including autistic features, and difficulties with attention and hyperactivity.

AIM

The aim of the present study was to systematically review studies that have focused on the prevalence of cognitive/developmental quotients (DQs) consistent with intellectual disability (ID), deficits in adaptive behavior, autism spectrum disorder (ASD), attention-deficit hyperactivity disorder (ADHD), and behavioral difficulties. A secondary aim was to consider possible factors associated with intellectual and behavioral outcomes in individuals with DS.

METHOD

A systematic review using PubMed and Scopus following the Preferred Reporting Items for Systematic Review (PRISMA) guidelines was conducted on the 24th of September 2019. Study quality was rated by two researchers using the National Institutes of Health (NIH) Quality assessment tools.

RESULT

Twenty-nine studies met inclusion criteria. The pooled prevalence of ID was 86% (range across studies: 50%-100%). The pooled prevalence for ASD was 31%. The mean level of adaptive behavior was more than 2 standard deviations (SDs) below average. The prevalence of behavioral difficulties on standardized instruments ranged between 37% and 100%. The only factor consistently associated with lower cognitive scores was age with older children having significantly lower cognitive scores than younger children. For behavioral difficulties, the most consistent association was with low health-related quality of life (HRQoL) with better HRQoL associated with fewer behavioral difficulties. Study quality was almost universally poor or fair - 15/29 studies were rated 'poor', 13/29 studies were 'fair', and 1 was 'good'.

DISCUSSION

The prevalence of cognitive scores consistent with ID is very high in DS. Many patients also have significant deficits in adaptive behavior highlighting that the majority of patients with DS will meet criteria for ID. The prevalence of ASD would also appear to be higher than the general population but studies show a wide range. Behavioral difficulties are common, but most studies have not used instruments adapted to patients with low intelligence quotient/DQ (IQ/DQ). No study used standardized instruments to assess ADHD. Few studies have used comprehensive statistical methods to evaluate possible factors associated with worse cognitive and behavioral outcome.

CONCLUSION

It should be routine to screen for cognitive and behavioral difficulties for all patients with DS. There is a need for more robust studies regarding intellectual and behavioral disorders in patients with DS. These should be large population-based or multinational studies that employ standardized instruments.

A propositional AI system for supporting epilepsy diagnosis based on the 2017 epilepsy classification: Illustrated by Dravet syndrome

PURPOSE

The 2017 epilepsy and seizure diagnosis framework emphasizes epilepsy syndromes and the etiology-based approach. We developed a propositional artificial intelligence (AI) system based on the above concepts to support physicians in the diagnosis of epilepsy.

METHODS

We analyzed and built ontology knowledge for the classification of seizure patterns, epilepsy, epilepsy syndrome, and etiologies. Protégé ontology tool was applied in this study. In order to enable the system to be close to the inferential thinking of clinical experts, we classified and constructed knowledge of other epilepsy-related knowledge, including comorbidities, epilepsy imitators, epilepsy descriptors, characteristic electroencephalography (EEG) findings, treatments, etc. We used the Ontology Web Language with Description Logic (OWL-DL) and Semantic Web Rule Language (SWRL) to design rules for expressing the relationship between these ontologies.

RESULTS

Dravet syndrome was taken as an illustration for epilepsy syndromes implementation. We designed an interface for the physician to enter the various characteristics of the patients. Clinical data of an 18-year-old boy with epilepsy was applied to the AI system. Through SWRL and reasoning engine Drool's execution, we successfully demonstrate the process of differential diagnosis.

CONCLUSION

We developed a propositional AI system by using the OWL-DL/SWRL approach to deal with the complexity of current epilepsy diagnosis. The experience of this system, centered on the clinical epilepsy syndromes, paves a path to construct an AI system for further complicated epilepsy diagnosis.

Dravet syndrome: Early electroclinical findings and long-term outcome in adolescents and adults

To describe the outcome of Dravet syndrome (DS) in adolescents and adults we conducted a longitudinal retrospective study of two independent cohorts of 34 adolescents (group 1) and 50 adults (group 2). In both cohorts, we collected information about genetic mutation, and semiology of seizures at onset and during disease course. At the last evaluation, we considered the following features: epilepsy (distinguishing myoclonic/complete and nonmyoclonic/incomplete phenotype), neurologic signs, intellectual disability (ID), and behavioral disorders. Moreover, in both cohorts, we performed a correlation analysis between early characteristics of the disease and the outcome of DS with regard to seizure persistence, ID, behavioral disorder, and neurologic impairment at last evaluation. Group 1 includes 22 adolescents with complete form of DS and 12 with incomplete form; group 2 includes 35 adults with complete form and 15 with incomplete form. The seizures persisted in 73.6% of adolescents and in 80% of adults, but epilepsy severity progressively decreased through age. Seizure persistence correlated with the complete phenotype and with the occurrence of reflex seizures. At last evaluation, ID was moderate or severe in 70.5% of adolescents and in 80% of adults. The most severe cognitive and motor impairment was observed in patients with persisting seizures. The severity of cognition, language, and neurologic impairment at last evaluation correlated statistically with the complete phenotype. The study confirms that the global outcome of DS is poor in most cases, albeit epilepsy severity decreases throughout adulthood. The improvement of epilepsy throughout ages is not associated with improvement in intellectual abilities and motor skills; this confirms that the unfavorable outcome is not a pure consequence of epilepsy.

Impact on Clinical Decision Making of Next-Generation Sequencing in Pediatric Epilepsy in a Tertiary Epilepsy Referral Center

Background. Next-generation sequencing (NGS) describes new powerful techniques of nucleic acid analysis, which allow not only disease gene identification diagnostics but also applications for transcriptome/methylation analysis and meta-genomics. NGS helps identify many monogenic epilepsy syndromes. Pediatric epilepsy patients can be tested using NGS epilepsy panels to diagnose them, thereby influencing treatment choices. The primary objective of this study was to evaluate the impact of genetic testing on clinical decision making in pediatric epilepsy patients. Methods. We completed a single-center retrospective cohort study of 91 patients (43 male) aged 19 years or less undergoing NGS with epilepsy panels differing in size ranging from 5 to 434 genes from October 2013 to September 2017. Results. During a mean time of 3.6 years between symptom onset and genetic testing, subjects most frequently showed epileptic encephalopathy (40%), focal epilepsy (33%), and generalized epilepsy (18%). In 16 patients (18% of the study population), "pathogenic" or "likely pathogenic" results according to ACMG criteria were found. Ten of the 16 patients (63%) experienced changes in clinical management regarding their medication and avoidance of further diagnostic evaluation, that is, presurgical evaluation. Conclusion. NGS epilepsy panels contribute to the diagnosis of pediatric epilepsy patients and may change their clinical management with regard to both preventing unnecessary and potentially harmful diagnostic procedures and management. Thus, the present data support the early implementation in order to adopt clinical management in selected cases and prevent further invasive investigations. Given the relatively small sample size and heterogeneous panels a larger prospective study with more homogeneous panels would be helpful to further determine the impact of NGS on clinical decision making.