Genetic influences on epilepsy outcomes: A whole-exome sequencing and health care records data linkage study

OBJECTIVE

This study was undertaken to develop a novel pathway linking genetic data with routinely collected data for people with epilepsy, and to analyze the influence of rare, deleterious genetic variants on epilepsy outcomes.

METHODS

We linked whole-exome sequencing (WES) data with routinely collected primary and secondary care data and natural language processing (NLP)-derived seizure frequency information for people with epilepsy within the Secure Anonymised Information Linkage Databank. The study participants were adults who had consented to participate in the Swansea Neurology Biobank, Wales, between 2016 and 2018. DNA sequencing was carried out as part of the Epi25 collaboration. For each individual, we calculated the total number and cumulative burden of rare and predicted deleterious genetic variants and the total of rare and deleterious variants in epilepsy and drug metabolism genes. We compared these measures with the following outcomes: (1) no unscheduled hospital admissions versus unscheduled admissions for epilepsy, (2) antiseizure medication (ASM) monotherapy versus polytherapy, and (3) at least 1 year of seizure freedom versus <1 year of seizure freedom.

RESULTS

We linked genetic data for 107 individuals with epilepsy (52% female) to electronic health records. Twenty-six percent had unscheduled hospital admissions, and 70% were prescribed ASM polytherapy. Seizure frequency information was linked for 100 individuals, and 10 were seizure-free. There was no significant difference between the outcome groups in terms of the exome-wide and gene-based burden of rare and deleterious genetic variants.

SIGNIFICANCE

We successfully uploaded, annotated, and linked genetic sequence data and NLP-derived seizure frequency data to anonymized health care records in this proof-of-concept study. We did not detect a genetic influence on real-world epilepsy outcomes, but our study was limited by a small sample size. Future studies will require larger (WES) data to establish genetic variant contribution to epilepsy outcomes.

Development of a novel and more holistic approach for assessing impact in health and medical research: the Research Impact Assessment Framework

Considered investment in health and medical research (HMR) is critical for fostering a healthcare system that is sustainable, effective, responsive, and innovative. While several tools exist to measure the impact of research, few assess the research environment that nurtures and supports impactful research and the strategic alignment of research with societal needs. This perspective article discusses the limitations of existing assessment tools and presents a novel Research Impact Assessment Framework designed to enable more strategic and targeted investment towards HMR, having the potential for significant public benefit.

GWAS meta-analysis of over 29,000 people with epilepsy identifies 26 risk loci and subtype-specific genetic architecture

Epilepsy is a highly heritable disorder affecting over 50 million people worldwide, of which about one-third are resistant to current treatments. Here we report a multi-ancestry genome-wide association study including 29,944 cases, stratified into three broad categories and seven subtypes of epilepsy, and 52,538 controls. We identify 26 genome-wide significant loci, 19 of which are specific to genetic generalized epilepsy (GGE). We implicate 29 likely causal genes underlying these 26 loci. SNP-based heritability analyses show that common variants explain between 39.6% and 90% of genetic risk for GGE and its subtypes. Subtype analysis revealed markedly different genetic architectures between focal and generalized epilepsies. Gene-set analyses of GGE signals implicate synaptic processes in both excitatory and inhibitory neurons in the brain. Prioritized candidate genes overlap with monogenic epilepsy genes and with targets of current antiseizure medications. Finally, we leverage our results to identify alternate drugs with predicted efficacy if repurposed for epilepsy treatment.

Complement activation and increased anaphylatoxin receptor expression are associated with cortical grey matter lesions and the compartmentalised inflammatory response of multiple sclerosis

Background

The extent of cortical pathology is an important determinant of multiple sclerosis (MS) severity. Cortical demyelination and neurodegeneration are related to inflammation of the overlying leptomeninges, a more inflammatory CSF milieu and with parenchymal microglia and astroglia activation. These are all components of the compartmentalised inflammatory response. Compartmentalised inflammation is a feature of progressive MS, which is not targeted by disease modifying therapies. Complement is differentially expressed in the MS CSF and complement, and complement receptors, are associated with demyelination and neurodegeneration.

Methods

To better understand if complement activation in the leptomeninges is associated with underlying cortical demyelination, inflammation, and microglial activation, we performed a neuropathological study of progressive MS (n = 22, 14 females), neuroinflammatory (n = 8), and non-neurological disease controls (n = 10). We then quantified the relative extent of demyelination, connective tissue inflammation, complement, and complement receptor positive microglia/macrophages.

Results

Complement was elevated at the leptomeninges, subpial, and within and around vessels of the cortical grey matter. The extent of complement C1q immunoreactivity correlated with connective tissue infiltrates, whilst activation products C4d, Bb, and C3b associated with grey matter demyelination, and C3a receptor 1+ and C5a receptor 1+ microglia/macrophages closely apposed C3b labelled cells. The density of C3a receptor 1+ and C5a receptor 1+ cells was increased at the expanding edge of subpial and leukocortical lesions. C5a receptor 1+ cells expressed TNFα, iNOS and contained puncta immunoreactive for proteolipid protein, neurofilament and synaptophysin, suggesting their involvement in grey matter lesion expansion.

Interpretation

The presence of products of complement activation at the brain surfaces, their association with the extent of underlying pathology and increased complement anaphylatoxin receptor positive microglia/macrophages at expanding cortical grey matter lesions, could represent a target to modify compartmentalised inflammation and cortical demyelination.

A founder event causing a dominant childhood epilepsy survives 800 years through weak selective pressure

Genetic epilepsy with febrile seizures plus (GEFS+) is an autosomal dominant familial epilepsy syndrome characterized by distinctive phenotypic heterogeneity within families. The SCN1B c.363C>G (p.Cys121Trp) variant has been identified in independent, multi-generational families with GEFS+. Although the variant is present in population databases (at very low frequency), there is strong clinical, genetic, and functional evidence to support pathogenicity. Recurrent variants may be due to a founder event in which the variant has been inherited from a common ancestor. Here, we report evidence of a single founder event giving rise to the SCN1B c.363C>G variant in 14 independent families with epilepsy. A common haplotype was observed in all families, and the age of the most recent common ancestor was estimated to be approximately 800 years ago. Analysis of UK Biobank whole-exome-sequencing data identified 74 individuals with the same variant. All individuals carried haplotypes matching the epilepsy-affected families, suggesting all instances of the variant derive from a single mutational event. This unusual finding of a variant causing an autosomal dominant, early-onset disease in an outbred population that has persisted over many generations can be attributed to the relatively mild phenotype in most carriers and incomplete penetrance. Founder events are well established in autosomal recessive and late-onset disorders but are rarely observed in early-onset, autosomal dominant diseases. These findings suggest variants present in the population at low frequencies should be considered potentially pathogenic in mild phenotypes with incomplete penetrance and may be more important contributors to the genetic landscape than previously thought.

Epilepsy mortality in Wales during COVID-19

Purpose

We aimed to compare mortality rates in people with epilepsy in Wales during the pandemic with pre-pandemic rates.

Methods

We performed a retrospective study using population-scale anonymised health records. We identified deaths in people with epilepsy (DPWE), those with a diagnosis of epilepsy, and deaths associ- ated with epilepsy (DAE), where epilepsy was recorded as a cause of death. We compared death rates in 2020 with average rates in 2015–2019 using Poisson models.

Results

There were 188 DAE and 628 DPWE in Wales in 2020 (death rates: 7.7/100,000/year and 25.7/100,000/year). The average rates for DAE and DPWE from 2015 to 2019 were 5.8/100,000/year and 23.8/100,000/year, respectively. Death rate ratios (2020 compared to 2015–2019) for DAE were 1.34 (95%CI 1.14–1.57, p<0.001) and for DPWE were 1.08 (0.99–1.17, p = 0.09). The death rate ratios for non-COVID deaths (deaths without COVID mentioned on death certificates) for DAE were 1.17 (0.99–1.39, p = 0.06) and for DPWE were 0.96 (0.87–1.05, p = 0.37).

Conclusions

The significant increase in DAE in Wales during 2020 could be explained by the direct effect of COVID-19 infection. Non-COVID-19 deaths have not increased significantly but further work is needed to assess the longer-term impact.

204 Idiopathic intracranial hypertension in Wales: population characterisation, epidemiological trends and healthcare utilisation

Objective

To characterise the Welsh idiopathic intracranial hypertension (IIH) population, epidemiologi- cal trends and healthcare outcomes using routinely collected healthcare data.

Methods

We used primary and secondary care healthcare diagnostic codes within the Secure Anonymised Information Linkage databank to ascertain IIH cases and controls in a retrospective cohort study between 2003–2017. We validated IIH diagnosis codes using anonymised secondary care lists of IIH cases.

Results

We analysed 35 million patient years of data (2003–2017). There were 1765 cases of IIH in 2017 (85% female). The prevalence and incidence of IIH in 2017 was 76/100,000 and 7.8/100,000, significantly increased from 2003 (prevalence=12/100,000, incidence=2.3/100,000). IIH prevalence is associated with socio-economic deprivation and increasing body mass index (BMI). 9% of people with IIH had CSF shunts with less than 0.2% having bariatric surgery. Unscheduled hospital admissions were significantly higher in the IIH cohort compared to controls; and also in IIH patients with CSF shunts compared to those without.

Conclusions

IIH incidence and prevalence is increasing significantly, corresponding to population increases in BMI. This has important implications for healthcare professionals and policy makers given the comor- bidities, complications and increased healthcare utilisation and economic burden associated with IIH.

lotif_miah@hotmail.com

146 Epilepsy, deprivation and mortality in Wales 2005–2017

Background

Public Health England have recently reported that deaths associated with epilepsy are increasing and are associated with increased deprivation. We investigated comparable Welsh mortality trends and associations between epilepsy mortality and deprivation.

Method

We used routinely-collected health data within the Secure Anonymised Information Linkage (SAIL) Databank. We recorded deaths associated with epilepsy (DAE), epilepsy recorded on death certificates, and deaths in people with epilepsy (DPWE), people with diagnoses of epilepsy and epilepsy prescriptions before death. We compared death rates in different deprivation deciles adjusting for epilepsy prevalence.

Results

During 2005–2017 (41million patient-years) there were 2116 DAE and 7821 DPWE. DAE and DPWE increased from 4.3/100,000/yr and 17.2/100,000/yr in 2005–2007 to 5.7/100,000/yr and 20.9/100,000/yr in 2015–2017. The age-standardised mortality rates (ASMR) in 2006–2008 for DAE and DPWE were 5.3/100,000/yr and 20/100,000/yr respectively, in 2015–2017 they were 5.8/100,000/yr and 20/100,000/yr. DAE were not significantly associated with deprivation when adjusted for epilepsy prevalence.

Conclusion

When adjusting for age, deaths associated wtih epilepsy and deaths in people with epilepsy did not increase significantly in Wales between 2005–2007 and 2015–2017. The association between dep- rivation and deaths associated with epilepsy appears to be explained by higher epilepsy prevalence in areas of higher deprivation.

w.o.pickrell@swansea.ac.uk

Sex-specific disease modifiers in juvenile myoclonic epilepsy

Juvenile myoclonic epilepsy (JME) is a common idiopathic generalised epilepsy with variable seizure prognosis and sex differences in disease presentation. Here, we investigate the combined epidemiology of sex, seizure types and precipitants, and their influence on prognosis in JME, through cross-sectional data collected by The Biology of Juvenile Myoclonic Epilepsy (BIOJUME) consortium. 765 individuals met strict inclusion criteria for JME (female:male, 1.8:1). 59% of females and 50% of males reported triggered seizures, and in females only, this was associated with experiencing absence seizures (OR = 2.0, p < 0.001). Absence seizures significantly predicted drug resistance in both males (OR = 3.0, p = 0.001) and females (OR = 3.0, p < 0.001) in univariate analysis. In multivariable analysis in females, catamenial seizures (OR = 14.7, p = 0.001), absence seizures (OR = 6.0, p < 0.001) and stress-precipitated seizures (OR = 5.3, p = 0.02) were associated with drug resistance, while a photoparoxysmal response predicted seizure freedom (OR = 0.47, p = 0.03). Females with both absence seizures and stress-related precipitants constitute the prognostic subgroup in JME with the highest prevalence of drug resistance (49%) compared to females with neither (15%) and males (29%), highlighting the unmet need for effective, targeted interventions for this subgroup. We propose a new prognostic stratification for JME and suggest a role for circuit-based risk of seizure control as an avenue for further investigation.

Epilepsy mortality in Wales during COVID-19

PURPOSE

The COVID-19 pandemic has increased mortality worldwide and those with chronic conditions may have been disproportionally affected. However, it is unknown whether the pandemic has changed mortality rates for people with epilepsy. We aimed to compare mortality rates in people with epilepsy in Wales during the pandemic with pre-pandemic rates.

METHODS

We performed a retrospective study using individual-level linked population-scale anonymised electronic health records. We identified deaths in people with epilepsy (DPWE), i.e. those with a diagnosis of epilepsy, and deaths associated with epilepsy (DAE), where epilepsy was recorded as a cause of death on death certificates. We compared death rates in 2020 with average rates in 2015-2019 using Poisson models to calculate death rate ratios.

RESULTS

There were 188 DAE and 628 DPWE in Wales in 2020 (death rates: 7.7/100,000/year and 25.7/100,000/year). The average rates for DAE and DPWE from 2015 to 2019 were 5.8/100,000/year and 23.8/100,000/year, respectively. Death rate ratios (2020 compared to 2015-2019) for DAE were 1.34 (95%CI 1.14-1.57, p<0.001) and for DPWE were 1.08 (0.99-1.17, p = 0.09). The death rate ratios for non-COVID deaths (deaths without COVID mentioned on death certificates) for DAE were 1.17 (0.99-1.39, p = 0.06) and for DPWE were 0.96 (0.87-1.05, p = 0.37).

CONCLUSIONS

The significant increase in DAE in Wales during 2020 could be explained by the direct effect of COVID-19 infection. Non-COVID-19 deaths have not increased significantly but further work is needed to assess the longer-term impact.

Epilepsy, antiepileptic drugs, and the risk of major cardiovascular events

OBJECTIVE

This study was undertaken to determine whether epilepsy and antiepileptic drugs (including enzyme-inducing and non-enzyme-inducing drugs) are associated with major cardiovascular events using population-level, routinely collected data.

METHODS

Using anonymized, routinely collected, health care data in Wales, UK, we performed a retrospective matched cohort study (2003-2017) of adults with epilepsy prescribed an antiepileptic drug. Controls were matched with replacement on age, gender, deprivation quintile, and year of entry into the study. Participants were followed to the end of the study for the occurrence of a major cardiovascular event, and survival models were constructed to compare the time to a major cardiovascular event (cardiac arrest, myocardial infarction, stroke, ischemic heart disease, clinically significant arrhythmia, thromboembolism, onset of heart failure, or a cardiovascular death) for individuals in the case group versus the control group.

RESULTS

There were 10 241 cases (mean age = 49.6 years, 52.2% male, mean follow-up = 6.1 years) matched to 35 145 controls. A total of 3180 (31.1%) cases received enzyme-inducing antiepileptic drugs, and 7061 (68.9%) received non-enzyme-inducing antiepileptic drugs. Cases had an increased risk of experiencing a major cardiovascular event compared to controls (adjusted hazard ratio = 1.58, 95% confidence interval [CI] = 1.51-1.63, p < .001). There was no notable difference in major cardiovascular events between those treated with enzyme-inducing antiepileptic drugs and those treated with non-enzyme-inducing antiepileptic drugs (adjusted hazard ratio = .95, 95% CI = .86-1.05, p = .300).

SIGNIFICANCE

Individuals with epilepsy prescribed antiepileptic drugs are at an increased risk of major cardiovascular events compared with population controls. Being prescribed an enzyme-inducing antiepileptic drug is not associated with a greater risk of a major cardiovascular event compared to treatment with other antiepileptic drugs. Our data emphasize the importance of cardiovascular risk management in the clinical care of people with epilepsy.

Incidence, Prevalence, and Health Care Outcomes in Idiopathic Intracranial Hypertension: A Population Study

OBJECTIVE

To characterize trends in incidence, prevalence, and health care outcomes in the idiopathic intracranial hypertension (IIH) population in Wales using routinely collected health care data.

METHODS

We used and validated primary and secondary care IIH diagnosis codes within the Secure Anonymised Information Linkage databank to ascertain IIH cases and controls in a retrospective cohort study between 2003 and 2017. We recorded body mass index (BMI), deprivation quintile, CSF diversion surgery, and unscheduled hospital admissions in case and control cohorts.

RESULTS

We analyzed 35 million patient-years of data. There were 1,765 cases of IIH in 2017 (85% female). The prevalence and incidence of IIH in 2017 was 76/100,000 and 7.8/100,000/y, a significant increase from 2003 (corresponding figures = 12/100,000 and 2.3/100,000/y) (p < 0.001). IIH prevalence is associated with increasing BMI and increasing deprivation. The odds ratio for developing IIH in the least deprived quintile compared to the most deprived quintile, adjusted for sex and BMI, was 0.65 (95% confidence interval 0.55 to 0.76). Nine percent of IIH cases had CSF shunts with less than 0.2% having bariatric surgery. Unscheduled hospital admissions were higher in the IIH cohort compared to controls (rate ratio 5.28, p < 0.001) and in individuals with IIH and CSF shunts compared to those without shunts (rate ratio 2.02, p < 0.01).

CONCLUSIONS

IIH incidence and prevalence is increasing considerably, corresponding to population increases in BMI, and is associated with increased deprivation. This has important implications for health care professionals and policy makers given the comorbidities, complications, and increased health care utilization associated with IIH.

Missense variants in the N-terminal domain of the A isoform of FHF2/FGF13 cause an X-linked developmental and epileptic encephalopathy

Fibroblast growth factor homologous factors (FHFs) are intracellular proteins which regulate voltage-gated sodium (Nav) channels in the brain and other tissues. FHF dysfunction has been linked to neurological disorders including epilepsy. Here, we describe two sibling pairs and three unrelated males who presented in infancy with intractable focal seizures and severe developmental delay. Whole-exome sequencing identified hemi- and heterozygous variants in the N-terminal domain of the A isoform of FHF2 (FHF2A). The X-linked FHF2 gene (also known as FGF13) has alternative first exons which produce multiple protein isoforms that differ in their N-terminal sequence. The variants were located at highly conserved residues in the FHF2A inactivation particle that competes with the intrinsic fast inactivation mechanism of Nav channels. Functional characterization of mutant FHF2A co-expressed with wild-type Nav1.6 (SCN8A) revealed that mutant FHF2A proteins lost the ability to induce rapid-onset, long-term blockade of the channel while retaining pro-excitatory properties. These gain-of-function effects are likely to increase neuronal excitability consistent with the epileptic potential of FHF2 variants. Our findings demonstrate that FHF2 variants are a cause of infantile-onset developmental and epileptic encephalopathy and underline the critical role of the FHF2A isoform in regulating Nav channel function.

Idiopathic Intracranial Hypertension in Wales

IntroductionIdiopathic Intracranial Hypertension (IIH) is a condition of unknown aetiology that is strongly associated with obesity. IIH predominantly affects women of childbearing age and causes chronic disabling headaches, visual disturbance and, in a minority of patients, permanent visual loss. Objectives and ApproachWe characterised the IIH population, epidemiological trends and healthcare outcomes in Wales using routinely collected healthcare data. We used primary and secondary care healthcare diagnosis codes within the Secure Anonymised Information Linkage databank to ascertain IIH cases and controls in a retrospective cohort study between 2003 and 2017. We validated IIH diagnosis codes using anonymised secondary care lists of IIH cases. ResultsWe analysed 35 million patient years of data (2003–2017). There were 1765 cases of IIH in 2017 (85% female). The prevalence and incidence of IIH in 2017 was 76/100,000 and 7.8/100,000/year, a significant increase from 2003 (corresponding figures=12/100,000 and 2.3/100,000/year). The odds ratio for developing IIH in the least deprived quintile compared to the most deprived quintile, adjusted for gender and Body Mass Index (BMI), was 0.65 (95% CI=0.55–0.76). 9% of people with IIH had CSF shunts with less than 0.2% having bariatric surgery. Unscheduled hospital admissions were significantly higher in the IIH cohort compared to controls (rate ratio=5.28, p<0.001) and in the people with IIH with CSF shunts compared to those without (rate ratio=2.02, p<0.01). Conclusion / ImplicationsIIH incidence and prevalence is increasing significantly, corresponding to population increases in BMI, and is associated with increased deprivation. This has important implications for healthcare professionals and policy makers given the comorbidities, complications and increased healthcare utilisation associated with IIH.

Trait impulsivity in Juvenile Myoclonic Epilepsy

Objective

Impulsivity is a multidimensional construct that can predispose to psychopathology. Meta‐analysis demonstrates an association between response impulsivity and Juvenile Myoclonic Epilepsy (JME), a common genetic generalized epilepsy. Here, we test the hypotheses that trait impulsivity is (i) elevated in JME compared to controls; (ii) moderated by specific seizure characteristics; and (iii) associated with psychiatric adverse effects of antiepileptic drugs (AEDs).

Methods

322 participants with JME and 126 age and gender‐matched controls completed the Barratt’s Impulsiveness Scale (BIS‐brief) alongside information on seizure history and AED use. We compared group BIS‐brief scores and assessed associations of JME BIS‐brief scores with seizure characteristics and AED adverse effects.

Results

The mean BIS‐brief score in JME was 18.1 ± 4.4 compared with 16.2 ± 4.1 in controls (P = 0.0007). Elevated impulsivity was associated with male gender (P = 0.027), frequent absence seizures (P = 0.0004) and lack of morning predominance of myoclonus (P = 0.008). High impulsivity significantly increased the odds of a psychiatric adverse event on levetiracetam (P = 0.036), but not any other psychiatric or somatic adverse effects.

Interpretation

Trait impulsivity is elevated in JME and comparable to scores in personality and neurotic disorders. Increased seizure frequency and absence of circadian seizure pattern moderate BIS score, suggesting disruption of both cortico‐striatal and thalamocortical networks as a shared mechanism between seizures and impulsivity in JME. These findings warrant consideration of impulsivity as a distinct target of intervention, and as a stratifying factor for AED treatment in JME, and perhaps other types of epilepsy. The role of impulsivity in treatment adherence and psychosocial outcome requires further investigation.

Ultra-Rare Genetic Variation in the Epilepsies: A Whole-Exome Sequencing Study of 17,606 Individuals

Sequencing-based studies have identified novel risk genes associated with severe epilepsies and revealed an excess of rare deleterious variation in less-severe forms of epilepsy. To identify the shared and distinct ultra-rare genetic risk factors for different types of epilepsies, we performed a whole-exome sequencing (WES) analysis of 9,170 epilepsy-affected individuals and 8,436 controls of European ancestry. We focused on three phenotypic groups: severe developmental and epileptic encephalopathies (DEEs), genetic generalized epilepsy (GGE), and non-acquired focal epilepsy (NAFE). We observed that compared to controls, individuals with any type of epilepsy carried an excess of ultra-rare, deleterious variants in constrained genes and in genes previously associated with epilepsy; we saw the strongest enrichment in individuals with DEEs and the least strong in individuals with NAFE. Moreover, we found that inhibitory GABA_A receptor genes were enriched for missense variants across all three classes of epilepsy, whereas no enrichment was seen in excitatory receptor genes. The larger gene groups for the GABAergic pathway or cation channels also showed a significant mutational burden in DEEs and GGE. Although no single gene surpassed exome-wide significance among individuals with GGE or NAFE, highly constrained genes and genes encoding ion channels were among the lead associations; such genes included CACNA1G, EEF1A2, and GABRG2 for GGE and LGI1, TRIM3, and GABRG2 for NAFE. Our study, the largest epilepsy WES study to date, confirms a convergence in the genetics of severe and less-severe epilepsies associated with ultra-rare coding variation, and it highlights a ubiquitous role for GABAergic inhibition in epilepsy etiology.

A homozygous ATAD1 mutation impairs postsynaptic AMPA receptor trafficking and causes a lethal encephalopathy

Members of the AAA+ superfamily of ATPases are involved in the unfolding of proteins and disassembly of protein complexes and aggregates. ATAD1 encoding the ATPase family, AAA+ domain containing 1-protein Thorase plays an important role in the function and integrity of mitochondria and peroxisomes. Postsynaptically, Thorase controls the internalization of excitatory, glutamatergic AMPA receptors by disassembling complexes between the AMPA receptor-binding protein, GRIP1, and the AMPA receptor subunit GluA2. Using whole-exome sequencing, we identified a homozygous frameshift mutation in the last exon of ATAD1 [c.1070_1071delAT; p.(His357Argfs*15)] in three siblings who presented with a severe, lethal encephalopathy associated with stiffness and arthrogryposis. Biochemical and cellular analyses show that the C-terminal end of Thorase mutant gained a novel function that strongly impacts its oligomeric state, reduces stability or expression of a set of Golgi, peroxisomal and mitochondrial proteins and affects disassembly of GluA2 and Thorase oligomer complexes. Atad1-/- neurons expressing Thorase mutantHis357Argfs*15 display reduced amount of GluA2 at the cell surface suggesting that the Thorase mutant may inhibit the recycling back and/or reinsertion of AMPA receptors to the plasma membrane. Taken together, our molecular and functional analyses identify an activating ATAD1 mutation as a new cause of severe encephalopathy and congenital stiffness.

Using natural language processing to extract structured epilepsy data from unstructured clinic letters: development and validation of the ExECT (extraction of epilepsy clinical text) system

OBJECTIVE

Routinely collected healthcare data are a powerful research resource but often lack detailed disease-specific information that is collected in clinical free text, for example, clinic letters. We aim to use natural language processing techniques to extract detailed clinical information from epilepsy clinic letters to enrich routinely collected data.

DESIGN

We used the general architecture for text engineering (GATE) framework to build an information extraction system, ExECT (extraction of epilepsy clinical text), combining rule-based and statistical techniques. We extracted nine categories of epilepsy information in addition to clinic date and date of birth across 200 clinic letters. We compared the results of our algorithm with a manual review of the letters by an epilepsy clinician.

SETTING

De-identified and pseudonymised epilepsy clinic letters from a Health Board serving half a million residents in Wales, UK.

RESULTS

We identified 1925 items of information with overall precision, recall and F1 score of 91.4%, 81.4% and 86.1%, respectively. Precision and recall for epilepsy-specific categories were: epilepsy diagnosis (88.1%, 89.0%), epilepsy type (89.8%, 79.8%), focal seizures (96.2%, 69.7%), generalised seizures (88.8%, 52.3%), seizure frequency (86.3%-53.6%), medication (96.1%, 94.0%), CT (55.6%, 58.8%), MRI (82.4%, 68.8%) and electroencephalogram (81.5%, 75.3%).

CONCLUSIONS

We have built an automated clinical text extraction system that can accurately extract epilepsy information from free text in clinic letters. This can enhance routinely collected data for research in the UK. The information extracted with ExECT such as epilepsy type, seizure frequency and neurological investigations are often missing from routinely collected data. We propose that our algorithm can bridge this data gap enabling further epilepsy research opportunities. While many of the rules in our pipeline were tailored to extract epilepsy specific information, our methods can be applied to other diseases and also can be used in clinical practice to record patient information in a structured manner.

Clinical spectrum of STX1B-related epileptic disorders

OBJECTIVE

The aim of this study was to expand the spectrum of epilepsy syndromes related to STX1B, encoding the presynaptic protein syntaxin-1B, and establish genotype-phenotype correlations by identifying further disease-related variants.

METHODS

We used next-generation sequencing in the framework of research projects and diagnostic testing. Clinical data and EEGs were reviewed, including already published cases. To estimate the pathogenicity of the variants, we used established and newly developed in silico prediction tools.

RESULTS

We describe 17 new variants in STX1B, which are distributed across the whole gene. We discerned 4 different phenotypic groups across the newly identified and previously published patients (49 patients in 23 families): (1) 6 sporadic patients or families (31 affected individuals) with febrile and afebrile seizures with a benign course, generally good drug response, normal development, and without permanent neurologic deficits; (2) 2 patients with genetic generalized epilepsy without febrile seizures and cognitive deficits; (3) 13 patients or families with intractable seizures, developmental regression after seizure onset and additional neuropsychiatric symptoms; (4) 2 patients with focal epilepsy. More often, we found loss-of-function mutations in benign syndromes, whereas missense variants in the SNARE motif of syntaxin-1B were associated with more severe phenotypes.

CONCLUSION

These data expand the genetic and phenotypic spectrum of STX1B-related epilepsies to a diverse range of epilepsies that span the International League Against Epilepsy classification. Variants in STX1B are protean and contribute to many different epilepsy phenotypes, similar to SCN1A, the most important gene associated with fever-associated epilepsies.

Educational attainment of children born to mothers with epilepsy

OBJECTIVE

Small prospective studies have identified that children exposed to valproate in utero have poorer scores on cognitive testing. We wanted to identify whether children exposed to antiepileptic drugs (AEDs) in utero have poorer school performance.

METHODS

We used anonymised, linked, routinely collected healthcare records to identify children born to mothers with epilepsy. We linked these children to their national attainment Key Stage 1 (KS1) tests in mathematics, language and science at the age of 7 and compared them with matched children born to mothers without epilepsy, and with the national KS1 results. We used the core subject indicator (CSI) as an outcome measure (the proportion of children achieving a minimum standard in all subjects) and the results in individual subjects.

RESULTS

We identified 440 children born to mothers with epilepsy with available KS1 results. Compared with a matched control group, fewer children with mothers being prescribed sodium valproate during pregnancy achieved the national minimum standard in CSI (-12.7% less than the control group), mathematics (-12.1%), language (-10.4%) and in science (-12.2%). Even fewer children with mothers being prescribed multiple AEDs during pregnancy achieved a national minimum standard: CSI (by -20.7% less than the control group), mathematics (-21.9%), language (-19.3%) and science (-19.4%). We did not observe any significant difference in children whose mothers were prescribed carbamazepine or were not taking an AED when compared with the control group.

CONCLUSIONS

In utero exposure to AEDs in combination, or sodium valproate alone, is associated with a significant decrease in attainment in national educational tests for 7-year-old children compared with both a matched control group and the all-Wales national average. These results give further support to the cognitive and developmental effects of in utero exposure to sodium valproate as well as multiple AEDs, which should be balanced against the need for effective seizure control for women during pregnancy.

The phenotype of bilateral hippocampal sclerosis and its management in "real life" clinical settings

OBJECTIVE

There is little detailed phenotypic characterization of bilateral hippocampal sclerosis (HS). We therefore conducted a multicenter review of people with pharmacoresistant epilepsy and bilateral HS to better determine their clinical characteristics.

METHODS

Databases from 11 EPIGEN centers were searched. For identified cases, clinicians reviewed the medical notes, imaging, and electroencephalographic (EEG), video-EEG, and neuropsychometric data. Data were irretrievably anonymized, and a single database was populated to capture all phenotypic information. These data were compared with phenotyped cases of unilateral HS from the same centers.

RESULTS

In total, 96 patients with pharmacoresistant epilepsy and bilateral HS were identified (43 female, 53 male; age range = 8-80 years). Twenty-five percent had experienced febrile convulsions, and 27% of patients had experienced status epilepticus. The mean number of previously tried antiepileptic drugs was 5.32, and the average number of currently prescribed medications was 2.99; 44.8% of patients had cognitive difficulties, and 47.9% had psychiatric comorbidity; 35.4% (34/96) of patients continued with long-term medical therapy alone, another 4 being seizure-free on medication. Sixteen patients proceeded to, or were awaiting, neurostimulation, and 11 underwent surgical resection. One patient was rendered seizure-free postresection, with an improvement in seizures for 3 other cases. By comparison, of 201 patients with unilateral HS, a significantly higher number (44.3%) had febrile convulsions and only 11.4% had experienced status epilepticus. Importantly, 41.8% (84/201) of patients with unilateral HS had focal aware seizures, whereas such seizures were less frequently observed in people with bilateral HS, and were never observed exclusively (P = .002; Fisher's exact test).

SIGNIFICANCE

The current work describes the phenotypic spectrum of people with pharmacoresistant epilepsy and bilateral HS, highlights salient clinical differences from patients with unilateral HS, and provides a large platform from which to develop further studies, both epidemiological and genomic, to better understand etiopathogenesis and optimal treatment regimes in this condition.

De novo mutations in GRIN1 cause extensive bilateral polymicrogyria

Polymicrogyria is a malformation of cortical development. The aetiology of polymicrogyria remains poorly understood. Using whole-exome sequencing we found de novo heterozygous missense GRIN1 mutations in 2 of 57 parent-offspring trios with polymicrogyria. We found nine further de novo missense GRIN1 mutations in additional cortical malformation patients. Shared features in the patients were extensive bilateral polymicrogyria associated with severe developmental delay, postnatal microcephaly, cortical visual impairment and intractable epilepsy. GRIN1 encodes GluN1, the essential subunit of the N-methyl-d-aspartate receptor. The polymicrogyria-associated GRIN1 mutations tended to cluster in the S2 region (part of the ligand-binding domain of GluN1) or the adjacent M3 helix. These regions are rarely mutated in the normal population or in GRIN1 patients without polymicrogyria. Using two-electrode and whole-cell voltage-clamp analysis, we showed that the polymicrogyria-associated GRIN1 mutations significantly alter the in vitro activity of the receptor. Three of the mutations increased agonist potency while one reduced proton inhibition of the receptor. These results are striking because previous GRIN1 mutations have generally caused loss of function, and because N-methyl-d-aspartate receptor agonists have been used for many years to generate animal models of polymicrogyria. Overall, our results expand the phenotypic spectrum associated with GRIN1 mutations and highlight the important role of N-methyl-d-aspartate receptor signalling in the pathogenesis of polymicrogyria.

Validating epilepsy diagnoses in routinely collected data

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Cases with and without epilepsy were linked with anonymised primary care data.

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Primary care diagnosis and drug codes accurately identify the cases with epilepsy.

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Drug codes alone can be used to identify children with epilepsy.

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Combining drug and diagnosis codes for adults and children increases accuracy.

Purpose

Anonymised, routinely-collected healthcare data is increasingly being used for epilepsy research. We validated algorithms using general practitioner (GP) primary healthcare records to identify people with epilepsy from anonymised healthcare data within the Secure Anonymised Information Linkage (SAIL) databank in Wales, UK.

Method

A reference population of 150 people with definite epilepsy and 150 people without epilepsy was ascertained from hospital records and linked to records contained within SAIL (containing GP records for 2.4 million people). We used three different algorithms, using combinations of GP epilepsy diagnosis and anti-epileptic drug (AED) prescription codes, to identify the reference population.

Results

Combining diagnosis and AED prescription codes had a sensitivity of 84% (95% ci 77–90) and specificity of 98% (95–100) in identifying people with epilepsy; diagnosis codes alone had a sensitivity of 86% (80–91) and a specificity of 97% (92–99); and AED prescription codes alone achieved a sensitivity of 92% (70–83) and a specificity of 73% (65–80). Using AED codes only was more accurate in children achieving a sensitivity of 88% (75–95) and specificity of 98% (88–100).

Conclusion

GP epilepsy diagnosis and AED prescription codes can be confidently used to identify people with epilepsy using anonymised healthcare records in Wales, UK.

Obtaining structured clinical data from unstructured data using natural language processing software

ABSTRACT BackgroundFree text documents in healthcare settings contain a wealth of information not captured in electronic healthcare records (EHRs). Epilepsy clinic letters are an example of an unstructured data source containing a large amount of intricate disease information. Extracting meaningful and contextually correct clinical information from free text sources, to enhance EHRs, remains a significant challenge. SCANR (Swansea University Collaborative in the Analysis of NLP Research) was set up to use natural language processing (NLP) technology to extract structured data from unstructured sources. IBM Watson Content Analytics software (ICA) uses NLP technology. It enables users to define annotations based on dictionaries and language characteristics to create parsing rules that highlight relevant items. These include clinical details such as symptoms and diagnoses, medication and test results, as well as personal identifiers.   ApproachTo use ICA to build a pipeline to accurately extract detailed epilepsy information from clinic letters. MethodsWe used ICA to retrieve important epilepsy information from 41 pseudo-anonymized unstructured epilepsy clinic letters. The 41 letters consisted of 13 ‘new’ and 28 ‘follow-up’ letters (for 15 different patients) written by 12 different doctors in different styles. We designed dictionaries and annotators to enable ICA to extract epilepsy type (focal, generalized or unclassified), epilepsy cause, age of onset, investigation results (EEG, CT and MRI), medication, and clinic date. Epilepsy clinicians assessed the accuracy of the pipeline. ResultsThe accuracy (sensitivity, specificity) of each concept was: epilepsy diagnosis 98% (97%, 100%), focal epilepsy 100%, generalized epilepsy 98% (93%, 100%), medication 95% (93%, 100%), age of onset 100% and clinic date 95% (95%, 100%). Precision and recall for each concept were respectively, 98% and 97% for epilepsy diagnosis, 100% each for focal epilepsy, 100% and 93% for generalized epilepsy, 100% each for age of onset, 100% and 93% for medication, 100% and 96% for EEG results, 100% and 83% for MRI scan results, and 100% and 95% for clinic date. Conclusions ICA is capable of extracting detailed, structured epilepsy information from unstructured clinic letters to a high degree of accuracy. This data can be used to populate relational databases and be linked to EHRs. Researchers can build in custom rules to identify concepts of interest from letters and produce structured information. We plan to extend our work to hundreds and then thousands of clinic letters, to provide phenotypically rich epilepsy data to link with other anonymised, routinely collected data.

Codifying unstructured data: A Natural Language Processing approach to extract rich data from clinical letters

ABSTRACT ObjectivesElectronic healthcare records (EHR) are the main data sources that facilitate epidemiology research. Routinely collected data such as primary and secondary care are now easily linked to produce novel and high impact research. There are, however, rich data locked in the free text of clinical letters that are not otherwise translated into EHRs. It is highly desirable to be able to extract this information to strengthen the body of information in existing EHRs. The Swansea Collaborative in Analysis of NLP Research (SCANR) group at Swansea University has been established to evaluate the usage of Natural Language Processing platforms for obtaining new clinical data. To use Clix Enrich to extract SNOMED concepts from a variety of clinical free texts and produce EHRs from the extraction process. Approach SNOMED concepts contain common items of interest such as diagnosis, medication and symptoms, as well as contextual concepts such as historical reference and negation. Clix Enrich uses the SNOMED dictionary to encode clinical free text (pre-co-ordinated) and find contextually correct SNOMED concepts (post co-ordinated). We used Clix Enrich to extract meaningful clinical terms from MS and Epilepsy consultant letters, as well as presenting complaint fields from a Welsh Emergency Department (ED). ResultsWe tailored Clix Enrich to extract a wide variety of clinical terms from each source (fourty texts per source) and validated the extraction accuracy with clinical experts in each domain. Clix Enrich was able to accurately extract the correct diagnosis for MS, Epilepsy and ED attendance (100%, 95% and 80%), dosage and frequency of anti-epileptic medication and MS modifying therapy (90%, 100%) and EDDS score (94%). We note a probable source of discrepancy in extraction accuracy between letter sources in the frequency of abbreviated terms, particularly within the presenting complaint field of the ED sample. ConclusionClix Enrich can be used to accurately extract SNOMED concepts from clinical letters. The resulting datasets are readily available to link to existing EHRs, and can be linked to EHRs that adopt the SNOMED coding structure, or backward compatible hierarchies. Clix Enrich comes with out-of-the-box extraction methods but the optimum way to extract the correct information would be to build in custom queries, thus requiring clinical expertise to validate extraction.

Hyperekplexia: Report on phenotype and genotype of 16 Jordanian patients

BACKGROUND

Hyperekplexia, is a rare disorder characterized by excessive startle response to acoustic, visual, or other stimuli. It is inherited in autosomal recessive and dominant pattern.

OBJECTIVE

To describe the clinical and genetic features of hyperekplexia in Jordanian patients.

METHODS

This retrospective study includes all patients with proved genetic diagnosis of hyperekplexia who presented to our clinic at the Jordan University Hospital from January 2001 through July 2015.

RESULTS

A total of 16 children from 12 families were included. The total follow up period ranged from one to eleven years. The majority of the patients (13/16=81.3%) were initially misdiagnosed as epilepsy. All patients had excessive startle response since birth. Tonic-apneic spells occurred in 15/16=93.8% patients. Fourteen patients (45/16=87.5%) received clonazepam. Stopping clonazepam by three years of age failed in 11/14 (78.6%) due to reappearance of tonic-apneic spells (8/14=57.1%), recurrent falling (10/14=71.4%) or due to both reasons (5/14=35.7%). Delayed motor development occurred in 7/16 (43.8%), speech delay in 4/16 (25.0%), global developmental delay in 1/16 (6.3%), and autism spectrum disorder in 1/16 (6.3%) patient. The mode of inheritance is autosomal recessive in all 12/12 (100%) families. Mutations in GLRA1 gene was present in 9/16 (56.3%); the most common mutation was in p.G254D (4/9; 44.5%). Mutations in the GLRB gene was present in 4/16 (25.0%) patients and the SLC6A5 gene in 3/16 (18.8%) patients.

CONCLUSION

The clinical presentation of hyperekplexia in Jordanian patients is manifested by tonic-apneic spells in all homozygous patients. The persistence of apneic spells and recurrent falls throughout childhood necessitate continuous treatment and surveillance.

Complement is activated in progressive multiple sclerosis cortical grey matter lesions

BACKGROUND

The symptoms of multiple sclerosis (MS) are caused by damage to myelin and nerve cells in the brain and spinal cord. Inflammation is tightly linked with neurodegeneration, and it is the accumulation of neurodegeneration that underlies increasing neurological disability in progressive MS. Determining pathological mechanisms at play in MS grey matter is therefore a key to our understanding of disease progression.

METHODS

We analysed complement expression and activation by immunocytochemistry and in situ hybridisation in frozen or formalin-fixed paraffin-embedded post-mortem tissue blocks from 22 progressive MS cases and made comparisons to inflammatory central nervous system disease and non-neurological disease controls.

RESULTS

Expression of the transcript for C1qA was noted in neurons and the activation fragment and opsonin C3b-labelled neurons and glia in the MS cortical and deep grey matter. The density of immunostained cells positive for the classical complement pathway protein C1q and the alternative complement pathway activation fragment Bb was significantly increased in cortical grey matter lesions in comparison to control grey matter. The number of cells immunostained for the membrane attack complex was elevated in cortical lesions, indicating complement activation to completion. The numbers of classical (C1-inhibitor) and alternative (factor H) pathway regulator-positive cells were unchanged between MS and controls, whilst complement anaphylatoxin receptor-bearing microglia in the MS cortex were found closely apposed to cortical neurons. Complement immunopositive neurons displayed an altered nuclear morphology, indicative of cell stress/damage, supporting our finding of significant neurodegeneration in cortical grey matter lesions.

CONCLUSIONS

Complement is activated in the MS cortical grey matter lesions in areas of elevated numbers of complement receptor-positive microglia and suggests that complement over-activation may contribute to the worsening pathology that underlies the irreversible progression of MS.

Pathogenic copy number variants and SCN1A mutations in patients with intellectual disability and childhood-onset epilepsy

Background

Copy number variants (CNVs) have been linked to neurodevelopmental disorders such as intellectual disability (ID), autism, epilepsy and psychiatric disease. There are few studies of CNVs in patients with both ID and epilepsy.

Methods

We evaluated the range of rare CNVs found in 80 Welsh patients with ID or developmental delay (DD), and childhood-onset epilepsy. We performed molecular cytogenetic testing by single nucleotide polymorphism array or microarray-based comparative genome hybridisation.

Results

8.8 % (7/80) of the patients had at least one rare CNVs that was considered to be pathogenic or likely pathogenic. The CNVs involved known disease genes (EHMT1, MBD5 and SCN1A) and imbalances in genomic regions associated with neurodevelopmental disorders (16p11.2, 16p13.11 and 2q13). Prompted by the observation of two deletions disrupting SCN1A we undertook further testing of this gene in selected patients. This led to the identification of four pathogenic SCN1A mutations in our cohort.

Conclusions

We identified five rare de novo deletions and confirmed the clinical utility of array analysis in patients with ID/DD and childhood-onset epilepsy. This report adds to our clinical understanding of these rare genomic disorders and highlights SCN1A mutations as a cause of ID and epilepsy, which can easily be overlooked in adults.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-016-0294-2) contains supplementary material, which is available to authorized users.

A NOVEL LGI1 VARIANT IN LATERAL TEMPORAL LOBE EPILEPSY

Background

We identified a family with autosomal dominant lateral temporal lobe epilepsy (ADLTLE). Given that LGI1 mutations account for around 50% of families with ADLTLE, we screened family members for LGI1 variants.

Method

We sequenced all exonic regions of LGI1 and used in-silico analysis tools to assess the potential affect of the novel variant. We screened 106 control samples for the variant and assessed the structural effect of the variant using a protein modelling platform.

Results

The proband's seizures consist of an unilateral ‘buzzing’ sensation which progresses to unilateral limb numbness and secondarily generalised seizures. Some noises can provoke seizures. Her mother also has epilepsy with identical seizure semiology. We identified a novel heterozygous missense LGI1 variant in the proband and her mother which was not present in other family members or control samples. This variant is close to the splice site region of LGI1 exon 4 and is predicted to be deleterious. Protein modelling suggests that the variant causes conformational structural changes.

Conclusion

We present a family with ADLTLE caused by a novel variant in LGI1. This variant is predicted to be deleterious, alters protein function and adds additional evidence for the role of LGI1 in ADLTLE.

Genome-wide Polygenic Burden of Rare Deleterious Variants in Sudden Unexpected Death in Epilepsy

Sudden unexpected death in epilepsy (SUDEP) represents the most severe degree of the spectrum of epilepsy severity and is the commonest cause of epilepsy-related premature mortality. The precise pathophysiology and the genetic architecture of SUDEP remain elusive. Aiming to elucidate the genetic basis of SUDEP, we analysed rare, protein-changing variants from whole-exome sequences of 18 people who died of SUDEP, 87 living people with epilepsy and 1479 non-epilepsy disease controls. Association analysis revealed a significantly increased genome-wide polygenic burden per individual in the SUDEP cohort when compared to epilepsy (P = 5.7 × 10(- 3)) and non-epilepsy disease controls (P = 1.2 × 10(- 3)). The polygenic burden was driven both by the number of variants per individual, and over-representation of variants likely to be deleterious in the SUDEP cohort. As determined by this study, more than a thousand genes contribute to the observed polygenic burden within the framework of this study. Subsequent gene-based association analysis revealed five possible candidate genes significantly associated with SUDEP or epilepsy, but no one single gene emerges as common to the SUDEP cases. Our findings provide further evidence for a genetic susceptibility to SUDEP, and suggest an extensive polygenic contribution to SUDEP causation. Thus, an overall increased burden of deleterious variants in a highly polygenic background might be important in rendering a given individual more susceptible to SUDEP. Our findings suggest that exome sequencing in people with epilepsy might eventually contribute to generating SUDEP risk estimates, promoting stratified medicine in epilepsy, with the eventual aim of reducing an individual patient's risk of SUDEP.

Recognizable cerebellar dysplasia associated with mutations in multiple tubulin genes

Mutations in alpha- and beta-tubulins are increasingly recognized as a major cause of malformations of cortical development (MCD), typically lissencephaly, pachygyria and polymicrogyria; however, sequencing tubulin genes in large cohorts of MCD patients has detected tubulin mutations in only 1-13%. We identified patients with a highly characteristic cerebellar dysplasia but without lissencephaly, pachygyria and polymicrogyria typically associated with tubulin mutations. Remarkably, in seven of nine patients (78%), targeted sequencing revealed mutations in three different tubulin genes (TUBA1A, TUBB2B and TUBB3), occurring de novo or inherited from a mosaic parent. Careful re-review of the cortical phenotype on brain imaging revealed only an irregular pattern of gyri and sulci, for which we propose the term tubulinopathy-related dysgyria. Basal ganglia (100%) and brainstem dysplasia (80%) were common features. On the basis of in silico structural predictions, the mutations affect amino acids in diverse regions of the alpha-/beta-tubulin heterodimer, including the nucleotide binding pocket. Cell-based assays of tubulin dynamics reveal various effects of the mutations on incorporation into microtubules: TUBB3 p.Glu288Lys and p.Pro357Leu do not incorporate into microtubules at all, whereas TUBB2B p.Gly13Ala shows reduced incorporation and TUBA1A p.Arg214His incorporates fully, but at a slower rate than wild-type. The broad range of effects on microtubule incorporation is at odds with the highly stereotypical clinical phenotype, supporting differential roles for the three tubulin genes involved. Identifying this highly characteristic phenotype is important due to the low recurrence risk compared with the other (recessive) cerebellar dysplasias and the apparent lack of non-neurological medical issues.

Epilepsy and deprivation, a data linkage study

OBJECTIVE

To investigate whether the link between epilepsy and deprivation is due to factors associated with deprivation (social causation) or factors associated with a diagnosis of epilepsy (social drift).

METHODS

We reviewed electronic primary health care records from 2004 to 2010, identifying prevalent and incident cases of epilepsy and recording linked deprivation scores. Logistic and Poisson regression models were used to calculate odds ratios and incidence rate ratios. The change in deprivation was measured 10 years after the initial diagnosis of epilepsy for a cohort of people.

RESULTS

Between 2004 and 2010, 8.1 million patient-years of records were reviewed. Epilepsy prevalence and incidence were significantly associated with deprivation. Epilepsy prevalence ranged from 1.13% (1.07-1.19%) in the most deprived decile to 0.49% (0.45-0.53%) in the least deprived decile (adjusted odds ratio 0.92, p < 0.001). Epilepsy incidence ranged from 40/100,000 per year in the most deprived decile to 19/100,000 per year in the least deprived decile (adjusted incidence rate ratio 0.94, p < 0.001). There was no statistically significant change in deprivation index decile 10 years after a new diagnosis of epilepsy (mean difference -0.04, p = 0.85).

SIGNIFICANCE

Epilepsy prevalence and incidence are strongly associated with deprivation; the deprivation score remains unchanged 10 years after a diagnosis of epilepsy. These findings suggest that increasing rates of epilepsy in deprived areas are more likely explained by social causation than by social drift. The nature of the association between incident epilepsy and social deprivation needs further exploration.

Ethnicity can predict GLRA1 genotypes in hyperekplexia

OBJECTIVES

Hyperekplexia is predominantly caused by mutations in the α-1 subunit of the inhibitory glycine receptor (GLRA1). Three quarters of cases show autosomal-recessive inheritance.

METHODS

We carefully ascertained reports of ethnicity from our hyperekplexia research cohort. These were compared with all published cases of hyperekplexia with an identified genetic cause. Ethnicities were subgrouped as Caucasian, Asian, Arabic, Turkish, Jewish or Afro-American.

RESULTS

We report the ethnicity of 90 cases: 56 cases from our service augmented by 34 cases from the literature. Homozygous deletions of exons 1 to 7 are predominantly seen in people with Turkish backgrounds (n=16/17, p<0.001). In contrast, the dominant point mutation R271 is seen in people of Asian, Caucasian and African-American heritage (n=19) but not in people with Arab or Turkish ethnicities (p<0.001).

CONCLUSIONS

Self-declared ethnicity can predict gene-screening outcomes. Cultural practices influence the inheritance patterns and a Caucasian founder is postulated for R271 mutations.

A comprehensive neuropsychological description of cognition in drug-refractory juvenile myoclonic epilepsy

The study of juvenile myoclonic epilepsy is important in that: it is common and heterogeneous; the etiology is unknown; and patients report broad cognitive problems. We utilized a broad battery of neuropsychometric tests to assess the following: intellectual function, memory, language and naming, executive function, the impact of epilepsy, and antiepilepsy drug side effects. Sixty people with drug-refractory JME were interviewed, and performance was profoundly impaired across the range of tests. Impairments included the following: full-scale IQ (89, p<0.001); processing speed (86, p<0.001); visual memory (immediate and delayed) more affected than verbal memory; verbal fluency and inhibition (p<0.001); and self-reported drug side effects (p<0.001). Eighty-three percent of patients exhibited frank executive dysfunction, which was moderate to severe in 66%. Regression modeling confirmed that an early age at onset and the need for polytherapy were associated with poorer cognitive outcomes. This study confirms previous reports of executive dysfunction in a larger cohort and with greater statistical rigor. We also identified a high prevalence of neurotoxicity symptoms such as fatigue and poorer functioning across intellectual and memory tests than had previously been reported.

Executive functions and psychiatric symptoms in drug-refractory juvenile myoclonic epilepsy

PURPOSE

The pattern of executive dysfunction reported in juvenile myoclonic epilepsy (JME) resembles that of patients with cluster B personality disorders. This study examined whether executive dysfunction and maladaptive behavior reported in patients with JME are related.

METHOD

Sixty patients with drug-refractory JME were administered tests of intellect, memory, and executive dysfunction. Anxiety, depression, personality traits, impact of epilepsy, and perceived cognitive effects of antiepileptic drugs were measured.

RESULTS

Half of the cohort exhibited moderate to severe anxiety symptoms. The patients performed most poorly on naming ability and inhibition switching. Duration of epilepsy exacerbated poor performance on inhibition switching. Females presented with pathological scores for neurotic and introvert traits and males for introvert traits. Abnormal personality traits and psychiatric disorders were associated with worse intellectual and executive functioning. People with extreme Eysenck Personality Scale - Brief Version (EPQ-BV) scores demonstrated the greatest level of executive impairment. Furthermore, the same degree of dysfunction was not seen in any individual with unremarkable EPQ-BV scores.

CONCLUSION

This study indicates that specific patterns of executive dysfunction are related to maladaptive behavior in JME. Distinct behavioral patterns may be used to identify functional and anatomical differences between people with JME and for stratification to enable gene discovery.

De novo mutations in the beta-tubulin gene TUBB2A cause simplified gyral patterning and infantile-onset epilepsy

Tubulins, and microtubule polymers into which they incorporate, play critical mechanical roles in neuronal function during cell proliferation, neuronal migration, and postmigrational development: the three major overlapping events of mammalian cerebral cortex development. A number of neuronally expressed tubulin genes are associated with a spectrum of disorders affecting cerebral cortex formation. Such "tubulinopathies" include lissencephaly/pachygyria, polymicrogyria-like malformations, and simplified gyral patterns, in addition to characteristic extracortical features, such as corpus callosal, basal ganglia, and cerebellar abnormalities. Epilepsy is a common finding in these related disorders. Here we describe two unrelated individuals with infantile-onset epilepsy and abnormalities of brain morphology, harboring de novo variants that affect adjacent amino acids in a beta-tubulin gene TUBB2A. Located in a highly conserved loop, we demonstrate impaired tubulin and microtubule function resulting from each variant in vitro and by using in silico predictive modeling. We propose that the affected functional loop directly associates with the alpha-tubulin-bound guanosine triphosphate (GTP) molecule, impairing the intradimer interface and correct formation of the alpha/beta-tubulin heterodimer. This study associates mutations in TUBB2A with the spectrum of "tubulinopathy" phenotypes. As a consequence, genetic variations affecting all beta-tubulin genes expressed at high levels in the brain (TUBB2B, TUBB3, TUBB, TUBB4A, and TUBB2A) have been linked with malformations of cortical development.

New hyperekplexia mutations provide insight into glycine receptor assembly, trafficking, and activation mechanisms

Hyperekplexia is a syndrome of readily provoked startle responses, alongside episodic and generalized hypertonia, that presents within the first month of life. Inhibitory glycine receptors are pentameric ligand-gated ion channels with a definitive and clinically well stratified linkage to hyperekplexia. Most hyperekplexia cases are caused by mutations in the α1 subunit of the human glycine receptor (hGlyR) gene (GLRA1). Here we analyzed 68 new unrelated hyperekplexia probands for GLRA1 mutations and identified 19 mutations, of which 9 were novel. Electrophysiological analysis demonstrated that the dominant mutations p.Q226E, p.V280M, and p.R414H induced spontaneous channel activity, indicating that this is a recurring mechanism in hGlyR pathophysiology. p.Q226E, at the top of TM1, most likely induced tonic activation via an enhanced electrostatic attraction to p.R271 at the top of TM2, suggesting a structural mechanism for channel activation. Receptors incorporating p.P230S (which is heterozygous with p.R65W) desensitized much faster than wild type receptors and represent a new TM1 site capable of modulating desensitization. The recessive mutations p.R72C, p.R218W, p.L291P, p.D388A, and p.E375X precluded cell surface expression unless co-expressed with α1 wild type subunits. The recessive p.E375X mutation resulted in subunit truncation upstream of the TM4 domain. Surprisingly, on the basis of three independent assays, we were able to infer that p.E375X truncated subunits are incorporated into functional hGlyRs together with unmutated α1 or α1 plus β subunits. These aberrant receptors exhibit significantly reduced glycine sensitivity. To our knowledge, this is the first suggestion that subunits lacking TM4 domains might be incorporated into functional pentameric ligand-gated ion channel receptors.

Flow-induced ATP release in patient-specific arterial geometries--a comparative study of computational models

The importance of the endothelium in the local regulation of blood flow is reflected by its influence on vascular tone by means of vasodilatory responses to many physiological stimuli. Regulatory pathways are affected by mass transport and wall shear stress (WSS), via mechanotransduction mechanisms. In the present work, we review the most relevant computational models that have been proposed to date, and introduce a general framework for modelling the responses of the endothelium to alteration in the flow, with a view to understanding the biomechanical processes involved in the pathways to endothelial dysfunction. Simulations are performed on two different patient-specific stenosed carotid artery geometries to investigate the influence of WSS and mass transport phenomena upon the agonist coupling response at the endothelium. In particular, results presented for two different models of WSS-dependent adenosine-5'-triphosphate (ATP) release reveal that existing paradigms may not account for the conditions encountered in vivo and may therefore not be adequate to model the kinetics of ATP at the endothelium.

Weight change associated with antiepileptic drugs

AIM

To investigate antiepileptic drug (AED)-related weight changes in patients with epilepsy through a retrospective observational study.

METHOD

We analysed the anonymised electronic primary care records of 1.1 million adult patients in Wales. We included patients aged 18 years and over with a diagnosis of epilepsy, whose body weight had been measured up to 12 months before starting, and between 3 and 12 months after starting, one of five AEDs. We calculated the weight difference after starting the AED for each patient.

RESULTS

1423 patients were identified in total. The mean difference between body weight after and before starting each AED (together with 95% CI and p values for no difference) were: carbamazepine (CBZ) 0.43 (-0.19 to 1.05) p=0.17; lamotrigine (LTG) 0.31 (-0.38 to 1.00) p=0.38; levetiracetam (LEV) 1.00 (0.16 to 1.84) p=0.02; sodium valproate (VPA) 0.74 (0.10 to 1.38) p=0.02; topiramate (TPM) -2.30 (-4.27 to -0.33) p=0.02.

CONCLUSIONS

LEV and VPA were associated with significant weight gain, TPM was associated with significant weight loss, and LTG and CBZ were not associated with significant weight change.

Ghrelin inhibits LPS-induced release of IL-6 from mouse dopaminergic neurones

BACKGROUND

Ghrelin is an orexigenic stomach hormone that acts centrally to increase mid-brain dopamine neurone activity, amplify dopamine signaling and protect against neurotoxin-induced dopamine cell death in the mouse substantia nigra pars compacta (SNpc). In addition, ghrelin inhibits the lipopolysaccharide (LPS)-induced release of pro-inflammatory cytokines from peripheral macrophages, T-cells and from LPS stimulated microglia. Here we sought to determine whether ghrelin attenuates pro-inflammatory cytokine release from dopaminergic neurones.

FINDINGS

The dopaminergic SN4741 cell-line, which derives from the mouse substantia nigra (SN) and expresses the ghrelin-receptor (growth hormone secretagogue receptor (GHS-R)) and the ghrelin-O-acyl transferase (GOAT) enzyme, was used to determine the neuro-immunomodulatory action of ghrelin. We induced innate immune activation via LPS challenge (1 μg/ml) of SN4741 neurones that had been pre-cultured in the presence or absence of ghrelin (1, 10, 100 nM) for 4 h. After 24 h supernatants were collected for detection of IL-1 beta (IL-1β ), TNF alpha (TNF-α) and IL-6 cytokines via enzyme linked immunosorbent assay (ELISA) analysis. Nuclear translocation of the transcription factor nuclear factor kappa B (NF-κB) was analyzed by Western blotting, and to determine viability of treatments a cell viability assay and caspase-3 immunohistochemistry were performed.We provide evidence that while IL-1β and TNF-α were not detectable under any conditions, SN4741 neurones constitutively released IL-6 under basal conditions and treatment with LPS significantly increased IL-6 secretion. Pre-treatment of neurones with ghrelin attenuated LPS-mediated IL-6 release at 24 h, an affect that was inhibited by the GHS-R antagonist [D-Lys3]-GHRP-6. However, while ghrelin pre-treatment attenuated the LPS-mediated increase in NF-κB, there was no alteration in its nuclear translocation. Cell viability assay and caspase-3 immunocytochemistry demonstrated that the results were independent from activation of cytotoxic and/or apoptotic mechanisms in the neuronal population, respectively.

CONCLUSION

Our results provide evidence that the gut-hormone, ghrelin, attenuates IL-6 secretion to LPS challenge in mid-brain dopaminergic neurones. These data suggest that ghrelin may protect against dopaminergic SN nerve cell damage or death via modulation of the innate immune response.

Overlapping cortical malformations and mutations in TUBB2B and TUBA1A

Polymicrogyria and lissencephaly are causally heterogeneous disorders of cortical brain development, with distinct neuropathological and neuroimaging patterns. They can be associated with additional structural cerebral anomalies, and recurrent phenotypic patterns have led to identification of recognizable syndromes. The lissencephalies are usually single-gene disorders affecting neuronal migration during cerebral cortical development. Polymicrogyria has been associated with genetic and environmental causes and is considered a malformation secondary to abnormal post-migrational development. However, the aetiology in many individuals with these cortical malformations is still unknown. During the past few years, mutations in a number of neuron-specific α- and β-tubulin genes have been identified in both lissencephaly and polymicrogyria, usually associated with additional cerebral anomalies including callosal hypoplasia or agenesis, abnormal basal ganglia and cerebellar hypoplasia. The tubulin proteins form heterodimers that incorporate into microtubules, cytoskeletal structures essential for cell motility and function. In this study, we sequenced the TUBB2B and TUBA1A coding regions in 47 patients with a diagnosis of polymicrogyria and five with an atypical lissencephaly on neuroimaging. We identified four β-tubulin and two α-tubulin mutations in patients with a spectrum of cortical and extra-cortical anomalies. Dysmorphic basal ganglia with an abnormal internal capsule were the most consistent feature. One of the patients with a TUBB2B mutation had a lissencephalic phenotype, similar to that previously associated with a TUBA1A mutation. The remainder had a polymicrogyria-like cortical dysplasia, but the grey matter malformation was not typical of that seen in 'classical' polymicrogyria. We propose that the cortical malformations associated with these genes represent a recognizable tubulinopathy-associated spectrum that ranges from lissencephalic to polymicrogyric cortical dysplasias, suggesting shared pathogenic mechanisms in terms of microtubular function and interaction with microtubule-associated proteins.

Novel missense mutations in the glycine receptor β subunit gene (GLRB) in startle disease

Startle disease is a rare, potentially fatal neuromotor disorder characterized by exaggerated startle reflexes and hypertonia in response to sudden unexpected auditory, visual or tactile stimuli. Mutations in the GlyR α(1) subunit gene (GLRA1) are the major cause of this disorder, since remarkably few individuals with mutations in the GlyR β subunit gene (GLRB) have been found to date. Systematic DNA sequencing of GLRB in individuals with hyperekplexia revealed new missense mutations in GLRB, resulting in M177R, L285R and W310C substitutions. The recessive mutation M177R results in the insertion of a positively-charged residue into a hydrophobic pocket in the extracellular domain, resulting in an increased EC(50) and decreased maximal responses of α(1)β GlyRs. The de novo mutation L285R results in the insertion of a positively-charged side chain into the pore-lining 9' position. Mutations at this site are known to destabilize the channel closed state and produce spontaneously active channels. Consistent with this, we identified a leak conductance associated with spontaneous GlyR activity in cells expressing α(1)β(L285R) GlyRs. Peak currents were also reduced for α(1)β(L285R) GlyRs although glycine sensitivity was normal. W310C was predicted to interfere with hydrophobic side-chain stacking between M1, M2 and M3. We found that W310C had no effect on glycine sensitivity, but reduced maximal currents in α(1)β GlyRs in both homozygous (α(1)β(W310C)) and heterozygous (α(1)ββ(W310C)) stoichiometries. Since mild startle symptoms were reported in W310C carriers, this may represent an example of incomplete dominance in startle disease, providing a potential genetic explanation for the 'minor' form of hyperekplexia.

GLRB is the third major gene of effect in hyperekplexia

Glycinergic neurotransmission is a major inhibitory influence in the CNS and its disruption triggers a paediatric and adult startle disorder, hyperekplexia. The postsynaptic α(1)-subunit (GLRA1) of the inhibitory glycine receptor (GlyR) and the cognate presynaptic glycine transporter (SLC6A5/GlyT2) are well-established genes of effect in hyperekplexia. Nevertheless, 52% of cases (117 from 232) remain gene negative and unexplained. Ligand-gated heteropentameric GlyRs form chloride ion channels that contain the α(1) and β-subunits (GLRB) in a 2α(1):3β configuration and they form the predominant population of GlyRs in the postnatal and adult human brain, brainstem and spinal cord. We screened GLRB through 117 GLRA1- and SLC6A5-negative hyperekplexia patients using a multiplex-polymerase chain reaction and Sanger sequencing approach. The screening identified recessive and dominant GLRB variants in 12 unrelated hyperekplexia probands. This primarily yielded homozygous null mutations, with nonsense (n = 3), small indel (n = 1), a large 95 kb deletion (n = 1), frameshifts (n = 1) and one recurrent splicing variant found in four cases. A further three cases were found with two homozygous and one dominant GLRB missense mutations. We provide strong evidence for the pathogenicity of GLRB mutations using splicing assays, deletion mapping, cell-surface biotinylation, expression studies and molecular modelling. This study describes the definitive assignment of GLRB as the third major gene for hyperekplexia and impacts on the genetic stratification and biological causation of this neonatal/paediatric disorder. Driven principally by consanguineous homozygosity of GLRB mutations, the study reveals long-term additive phenotypic outcomes for affected cases such as severe apnoea attacks, learning difficulties and developmental delay.