Molecular genetics of febrile seizures

Twenty-four-hour pattern of children with febrile seizures presenting to a United States Pediatric Emergency Department

BACKGROUND

Febrile seizure (FS) is the most common convulsive disorder in children. Understanding its time-of-day pattern can provide insight into mechanisms and prevention.

PURPOSE

We explored clock-time variation of FS presentations of children to a US pediatric emergency department (PED) in comparison to two control cohorts: one (n = 5719) like-aged children presenting solely with fever, i.e., temperature > 100.4 °F/38°C, and one of children (n = 103,806) presenting for any medical emergency.

METHODS

Electronic medical records covering a 58-month span were searched for clock time of arrivals to the PED, with data assessed either by chi-square or Cosinor analyses to test for temporal variation and derive descriptive parameters.

MAJOR FINDINGS

Presentation of the 84 FS cases exhibited a time-of-day difference (p = .038), being 5-fold higher between 16:00-19:59 h than 08:00-11:59 h. Presentations of both control groups additionally exhibited such difference, with peak numbers between 16:00 and 19:59 h. Fever intensity of cases tended to be greater by 0.58 °F (p > .10) in those attending the PED between 16:00-23:59 h than 00:00-07:59 h. The control group of children solely with fever showed (p < .0001) time-of-day variation in body temperature, with the difference between presentations of highest and lowest temperature, respectively at ∼21:40 and ∼09:40 h, of 0.4 °F.

NOVELTY OF FINDINGS

This is the first study to report time-of-day variation in FS of American children, which is like that reported in children of other countries. The peak number of presentations for FS corresponds in time both with that for fever without seizure and that for any medical emergency, and, additionally, fever intensity of fever controls.

Febrile Seizures, Ongoing Epileptiform Activity, and the Resulting Long-Term Consequences: Lessons From Animal Models

Febrile seizures affect 2% to 14% of children. Prospective studies indicate that following a relatively prolonged febrile seizure there are long-term consequences. Although controlled experiments in children have ethical limitations, nonhuman animal models give us the ability to discover new phenomena, determine their mechanisms, and test treatments that can potentially translate to the human clinical population. Rat models of febrile seizures show two temporally distinct phases: (1); behavioral seizures and (2); ongoing epileptiform activity associated with hyperoxia. The behavioral seizures mimic those displayed by children including tonic-clonic convulsions and loss of postural control. Recordings show classic spiking discharges from cortical regions during the behavioral seizures. Following behavioral seizure termination electrical recordings in rodent models reveal that there is ongoing epileptiform activity that lasts longer than the duration of the behavioral seizures themselves. This ongoing epileptiform activity is also associated with hyperoxia-levels of brain tissue oxygen well above the normoxic zone (typical oxygen levels)-and can last more than an hour. When this hyperoxia, but not the epileptiform activity, is prevented in febrile rat pups the long-term learning impairments are also prevented. This leaves important questions unanswered, "Do children also have ongoing and long-lasting epileptiform activity and associated hyperoxia following termination of their febrile behavioral seizures and does this second phase have long-term consequences"? Here we discuss appropriate animal models of febrile seizures that replicate much of the human condition with special attention to the long-term effects of occult epileptiform activity following termination of a behavioral febrile seizure.

Prophylactic drug management for febrile seizures in children

BACKGROUND

Febrile seizures occurring in a child older than one month during an episode of fever affect 2-4% of children in Great Britain and the United States and recur in 30%. Rapid-acting antiepileptics and antipyretics given during subsequent fever episodes have been used to avoid the adverse effects of continuous antiepileptic drugs. This is an updated version of a Cochrane Review previously published in 2017.

OBJECTIVES

To evaluate primarily the effectiveness and safety of antiepileptic and antipyretic drugs used prophylactically to treat children with febrile seizures; and also to evaluate any other drug intervention where there is a sound biological rationale for its use.

SEARCH METHODS

For the latest update we searched the following databases on 3 February 2020: Cochrane Register of Studies (CRS Web), MEDLINE (Ovid, 1946 to 31 January 2020). CRS Web includes randomised or quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the specialised registers of Cochrane Review Groups including the Cochrane Epilepsy Group. We imposed no language restrictions and contacted researchers to identify continuing or unpublished studies.

SELECTION CRITERIA

Trials using randomised or quasi-randomised participant allocation that compared the use of antiepileptics, antipyretics or recognised Central Nervous System active agents with each other, placebo, or no treatment.

DATA COLLECTION AND ANALYSIS

For the original review, two review authors independently applied predefined criteria to select trials for inclusion and extracted the predefined relevant data, recording methods for randomisation, blinding, and exclusions. For the 2016 update, a third review author checked all original inclusions, data analyses, and updated the search. For the 2020 update, one review author updated the search and performed the data analysis following a peer-review process with the original review authors. We assessed seizure recurrence at 6, 12, 18, 24, 36, 48 months, and where data were available at age 5 to 6 years along with recorded adverse effects. We evaluated the presence of publication bias using funnel plots.

MAIN RESULTS

We included 42 articles describing 32 randomised trials, with 4431 randomised participants used in the analysis of this review. We analysed 15 interventions of continuous or intermittent prophylaxis and their control treatments. Methodological quality was moderate to poor in most studies. We found no significant benefit for intermittent phenobarbital, phenytoin, valproate, pyridoxine, ibuprofen, or zinc sulfate versus placebo or no treatment; nor for diclofenac versus placebo followed by ibuprofen, paracetamol, or placebo; nor for continuous phenobarbital versus diazepam, intermittent rectal diazepam versus intermittent valproate, or oral diazepam versus clobazam. There was a significant reduction of recurrent febrile seizures with intermittent diazepam versus placebo or no treatment at six months (risk ratio (RR) 0.64, 95% confidence interval (CI) 0.48 to 0.85; 6 studies, 1151 participants; moderate-certainty evidence), 12 months (RR 0.69, 95% CI 0.56 to 0.84; 8 studies, 1416 participants; moderate-certainty evidence), 18 months (RR 0.37, 95% CI 0.23 to 0.60; 1 study, 289 participants; low-certainty evidence), 24 months (RR 0.73, 95% CI 0.56 to 0.95; 4 studies, 739 participants; high-certainty evidence), 36 months (RR 0.58, 95% CI 0.40 to 0.85; 1 study, 139 participants; low-certainty evidence), 48 months (RR 0.36, 95% CI 0.15 to 0.89; 1 study, 110 participants; moderate-certainty evidence), with no benefit at 60 to 72 months (RR 0.08, 95% CI 0.00 to 1.31; 1 study, 60 participants; very low-certainty evidence). Phenobarbital versus placebo or no treatment reduced seizures at six months (RR 0.59, 95% CI 0.42 to 0.83; 6 studies, 833 participants; moderate-certainty evidence), 12 months (RR 0.54, 95% CI 0.42 to 0.70; 7 studies, 807 participants; low-certainty evidence), and 24 months (RR 0.69, 95% CI 0.53 to 0.89; 3 studies, 533 participants; moderate-certainty evidence), but not at 18 months (RR 0.77, 95% CI 0.56 to 1.05; 2 studies, 264 participants) or 60 to 72 months follow-up (RR 1.50, 95% CI 0.61 to 3.69; 1 study, 60 participants; very low-certainty evidence). Intermittent clobazam compared to placebo at six months resulted in a RR of 0.36 (95% CI 0.20 to 0.64; 1 study, 60 participants; low-certainty evidence), an effect found against an extremely high (83.3%) recurrence rate in the controls, a result that needs replication. When compared to intermittent diazepam, intermittent oral melatonin did not significantly reduce seizures at six months (RR 0.45, 95% CI 0.18 to 1.15; 1 study, 60 participants; very-low certainty evidence). When compared to placebo, intermittent oral levetiracetam significantly reduced recurrent seizures at 12 months (RR 0.27, 95% CI 0.15 to 0.52; 1 study, 115 participants; very low-certainty evidence). The recording of adverse effects was variable. Two studies reported lower comprehension scores in phenobarbital-treated children. Adverse effects were recorded in up to 30% of children in the phenobarbital-treated groups and 36% in benzodiazepine-treated groups. We found evidence of publication bias in the meta-analyses of comparisons for phenobarbital versus placebo (seven studies) at 12 months but not at six months (six studies); and valproate versus placebo (four studies) at 12 months. There were too few studies to identify publication bias for the other comparisons. The methodological quality of most of the included studies was low or very low. Methods of randomisation and allocation concealment often did not meet current standards, and 'treatment versus no treatment' was more commonly seen than 'treatment versus placebo', leading to obvious risks of bias.  AUTHORS' CONCLUSIONS: We found reduced recurrence rates for intermittent diazepam and continuous phenobarbital, with adverse effects in up to 30% of children. The apparent benefit for clobazam treatment in one trial needs to be replicated. Levetiracetam also shows benefit with a good safety profile; however, further study is required. Given the benign nature of recurrent febrile seizures, and the high prevalence of adverse effects of these drugs, parents and families should be supported with adequate contact details of medical services and information on recurrence, first aid management, and, most importantly, the benign nature of the phenomenon.

Putative Causal Variant on Vlgr1 for the Epileptic Phenotype in the Model Wistar Audiogenic Rat

Wistar Audiogenic Rat is an epilepsy model whose animals are predisposed to develop seizures induced by acoustic stimulation. This model was developed by selective reproduction and presents a consistent genetic profile due to the several generations of inbreeding. In this study, we performed an analysis of WAR RNA-Seq data, aiming identified at genetic variants that may be involved in the epileptic phenotype. Seventeen thousand eighty-five predicted variants were identified as unique to the WAR model, of which 15,915 variants are SNPs and 1,170 INDELs. We filter the predicted variants by pre-established criteria and selected five for validation by Sanger sequencing. The genetic variant c.14198T>C in the Vlgr1 gene was confirmed in the WAR model. Vlgr1 encodes an adhesion receptor that is involved in the myelination process, in the development of stereocilia of the inner ear, and was already associated with the audiogenic seizures presented by the mice Frings. The transcriptional quantification of Vlgr1 revealed the downregulation this gene in the corpus quadrigeminum of WAR, and the protein modeling predicted that the mutated residue alters the structure of a domain of the VLGR1 receptor. We believe that Vlgr1 gene may be related to the predisposition of WAR to seizures and suggest the mutation Vlgr1/Q4695R as putative causal variant, and the first molecular marker of the WAR strain.

A Review of Febrile Seizures: Recent Advances in Understanding of Febrile Seizure Pathophysiology and Commonly Implicated Viral Triggers

Febrile seizures are one of the commonest presentations in young children, with a 2-5% incidence in Western countries. Though they are generally benign, with rare long-term sequelae, there is much to be learned about their pathophysiology and risk factors. Febrile seizures are propagated by a variety of genetic and environmental factors, including viruses and vaccines. These factors must be taken into consideration by a clinician aiming to assess, diagnose and treat a child presenting with fevers and seizures, as well as to explain the sequelae of the febrile seizures to the concerned parents of the child. Our article provides an overview of this common childhood condition, outlining both the underlying mechanisms and the appropriate clinical approach to a child presenting with febrile seizures.

Identification of Missense ADGRV1 Mutation as a Candidate Genetic Cause of Familial Febrile Seizure 4

Febrile seizure (FS) is related to a febrile illness (temperature > 38 °C) not caused by an infection of central nervous system, without neurologic deficits in children aged 6–60 months. The family study implied a polygenic model in the families of proband(s) with single FS, however in families with repeated FS, inheritance was matched to autosomal dominance with reduced disease penetrance. A 20 month-old girl showed recurrent FS and afebrile seizures without developmental delay or intellectual disability. The seizures disappeared after 60 months without anti-seizure medication. The 35 year-old proband’s mother also experienced five episodes of simple FS and two episodes of unprovoked seizures before 5 years old. Targeted exome sequencing was conducted along with epilepsy/seizure-associated gene-filtering to identify the candidate causative mutation. As a result, a heterozygous c.2039A>G of the ADGRV1 gene leading to a codon change of aspartic acid to glycine at the position 680 (rs547076322) was identified. This protein’s glycine residue is highly conserved, and its allele frequency is 0.00002827 in the gnomAD population database. ADGRV1 mutation may have an influential role in the occurrence of genetic epilepsies, especially those with febrile and afebrile seizures. Further investigation of ADGRV1 mutations is needed to prove that it is a significant susceptible gene for febrile and/or afebrile seizures in early childhood.

Causality assessment of adverse events following immunization: the problem of multifactorial pathology

The analysis of Adverse Events Following Immunization (AEFI) is important in a balanced epidemiological evaluation of vaccines and in the issues related to national vaccine injury compensation programs. If manufacturing defects or vaccine storage and delivering errors are excluded, the majority of adverse reactions to vaccines occur as excessive or biased inflammatory and immune responses. These unwanted phenomena, occasionally severe, are associated with many different endogenous and exogenous factors, which often interact in complex ways. The confirmation or denial of the causal link between an AEFI and vaccination is determined pursuant to WHO guidelines, which propose a four-step analysis and algorithmic diagramming. The evaluation process from the onset considers all possible "other causes" that can explain the AEFI and thus exclude the role of the vaccine. Subsequently, even if there was biological plausibility and temporal compatibility for a causal association between the vaccine and the AEFI, the guidelines ask to look for any possible evidence that the vaccine could not have caused that event. Such an algorithmic method presents some concerns that are discussed here, in the light of the multifactorial nature of the inflammatory and immune pathologies induced by vaccines, including emerging knowledge of genetic susceptibility to adverse effects. It is proposed that the causality assessment could exclude a consistent association of the adverse event with the vaccine only when the presumed "other cause" is independent of an interaction with the vaccine. Furthermore, the scientific literature should be viewed not as an exclusion criterion but as a comprehensive analysis of all the evidence for or against the role of the vaccine in causing an adverse reaction. These issues are discussed in relation to the laws that, in some countries, regulate the mandatory vaccinations and the compensation for those who have suffered serious adverse effects.

Causality assessment of adverse events following immunization: the problem of multifactorial pathology

The analysis of Adverse Events Following Immunization (AEFI) is important in a balanced epidemiological evaluation of vaccines and in the issues related to vaccine injury compensation programs. The majority of adverse reactions to vaccines occur as excessive or biased inflammatory and immune responses. These unwanted phenomena, occasionally severe, are associated with many different endogenous and exogenous factors, which often interact in complex ways. The confirmation or denial of the causal link between an AEFI and vaccination is determined pursuant to WHO guidelines, which propose a four-step analysis and algorithmic diagramming. The evaluation process from the onset considers all possible "other causes" that might explain the AEFI and thus exclude the role of the vaccine. Subsequently, even if there was biological plausibility and temporal compatibility for a causal association between the vaccine and the AEFI, the guidelines ask to look for any possible evidence that the vaccine could not have caused that event. Such an algorithmic method presents several concerns that are discussed here, in the light of the multifactorial nature of the inflammatory and immune pathologies induced by vaccines, including emerging knowledge of genetic susceptibility to adverse effects. It is proposed that the causality assessment could exclude a consistent association of the adverse event with the vaccine only when the presumed "other cause" is independent of an interaction with the vaccine. Furthermore, the scientific literature should be viewed not as an exclusion criterion but as a comprehensive analysis of all the evidence for or against the role of the vaccine in causing an adverse reaction. Given these inadequacies in the evaluation of multifactorial diseases, the WHO guidelines need to be reevaluated and revised. These issues are discussed in relation to the laws that, in some countries, regulate the mandatory vaccinations and the compensation for those who have suffered serious adverse effects.

Anakinra Therapy for Non-cancer Inflammatory Diseases

Interleukin-1 (IL-1) is the prototypical inflammatory cytokine: two distinct ligands (IL-1α and IL-1β) bind the IL-1 type 1 receptor (IL-1R1) and induce a myriad of secondary inflammatory mediators, including prostaglandins, cytokines, and chemokines. IL-1α is constitutively present in endothelial and epithelial cells, whereas IL-1β is inducible in myeloid cells and released following cleavage by caspase-1. Over the past 30 years, IL-1-mediated inflammation has been established in a broad spectrum of diseases, ranging from rare autoinflammatory diseases to common conditions such as gout and rheumatoid arthritis (RA), type 2 diabetes, atherosclerosis, and acute myocardial infarction. Blocking IL-1 entered the clinical arena with anakinra, the recombinant form of the naturally occurring IL-1 receptor antagonist (IL-1Ra); IL-1Ra prevents the binding of IL-1α as well as IL-1β to IL-1R1. Quenching IL-1-mediated inflammation prevents the detrimental consequences of tissue damage and organ dysfunction. Although anakinra is presently approved for the treatment of RA and cryopyrin-associated periodic syndromes, off-label use of anakinra far exceeds its approved indications. Dosing of 100 mg of anakinra subcutaneously provides clinically evident benefits within days and for some diseases, anakinra has been used daily for over 12 years. Compared to other biologics, anakinra has an unparalleled record of safety: opportunistic infections, particularly Mycobacterium tuberculosis, are rare even in populations at risk for reactivation of latent infections. Because of this excellent safety profile and relative short duration of action, anakinra can also be used as a diagnostic tool for undefined diseases mediated by IL-1. Although anakinra is presently in clinical trials to treat cancer, this review focuses on anakinra treatment of acute as well as chronic inflammatory diseases.

Treatment of Inflammatory Diseases with IL-1 Blockade

Background

Autoinflammatory diseases are distinct from autoimmune diseases. Whereas autoinflammatory diseases are due to dysfunctional T-cells and B-cells, autoinflammatory diseases are due to overproduction of macrophage cytokines particularly interleukin-1 beta (IL-1β). A causative role for IL-1 in autoinflammatory diseases is derived from clinical studies blocking the IL-1 receptor or neutralizing monoclonal antibodies or soluble receptors.

Methods

A review was performed of clinical trials in autoinflammatory diseases using the IL-1 receptor antagonist (anakinra), the soluble IL-1 receptor (rilonacept), antibodies to IL-1β (canakinumab, gevokizumab) and anti-IL-1α (xilonix).

Findings

Anakinra blocks the IL-1 Receptor type 1 (IL-1R1) and therefore blocks the activities of both IL-1α and IL-1β. Off-label use of anakinra is common for a broad spectrum of inflammatory diseases. Neutralization of IL-1β is used to treat hereditary autoinflammatory diseases but also atherosclerosis. Rilonacept reduces arterial wall inflammation in patients with chronic kidney disease. Neutralization of IL-1α has prolonged life in patients with advanced metastatic colorectal cancer. Compared to other cytokine blocking therapies, reducing the activities of IL-1 has an excellent safety record.

Conclusions

Blocking IL-1 therapies can be used to treat a wide-spectrum of acute and chronic inflammatory diseases.

Interleukin-1β and interleukin-1receptor antagonist polymorphisms in Egyptian children with febrile seizures: A case-control study

Febrile seizure is the most common seizure disorder of childhood. Of the pro-inflammatory cytokines, interleukin-1 is defined as the first endogenous pyrogen.We designed this study to investigate single-nucleotide polymorphisms (SNPs) situated at positions -31 (C/T), and -511 (C/T) of interleukin-1beta (IL-1β) gene promoter and interleukin-1receptor antagonist (IL-1RA) gene variable number of tandem repeats in intron 2 (VNTR); to determine whether these polymorphisms could be a marker of susceptibility to febrile seizures in Egyptian children and we also measured the serum level of IL-1β to assess its relation to such polymorphisms.This was a case-control study included 155 patients with febrile seizure, and matched with age, sex, ethnicity 155 healthy control subjects. IL-1β promoter at positions -31 (C/T), -511 (C/T), and IL-1RA gene VNTR polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while the serum IL-1β levels were measured by enzyme-linked immunosorbent assay (ELISA) method.The frequency of the IL-1β-511 TT genotype and T allele at the same position were observed to be increased in patients with febrile seizures (FS) compared with the control group (odds ratio [OR]: 3.96; 95% confidence interval [CI]: 1.68-9.5; P = 0.001 for the TT genotype and OR: 1.65; 95% CI: 1.18-2.3; P = 0.003 for the T allele, respectively). The IL-1 RA II/II homozygous variant and IL-1 RA allele II were overrepresented in patients with FS than control group (OR: 4.02; 95% CI: 1.78-9.15; P = 0.001and OR: 1.73; 95% CI: 1.24-2.4; P = 0.001, respectively). We found a significant positive association between the IL-1 RA II/II genotype and susceptibility to FS in sporadic cases as did allele II at the same position (OR: 5.04; 95% CI: 2.1-12.5 for the IL-1 RA II/II genotype; P = 0.001) and (OR: 1.94; 95% CI: 1.3-2.8 for the allele II; P = 0.001, respectively). Carriers of the IL-1RA II/II homozygous variant and allele II had significantly higher serum levels of IL-1β compared with those with other genotypes and alleles.We demonstrate for the first time that the presence of a T allele or TT genotype at -511 of IL-1β promoter and IL-1RA II/II genotype constitute risk factors for developing FS in Egyptian children.

Prevalence, causes, and behavioral and emotional comorbidities of acute symptomatic seizures in Africa: A critical review

Seizures with fever includes both febrile seizures (due to nonneurological febrile infections) and acute symptomatic seizures (due to neurological febrile infections). The cumulative incidence (lifetime prevalence) of febrile seizures in children aged ≤6 years is 2-5% in American and European studies, but there are no community-based data on acute symptomatic seizures in Africa. The incidence of acute symptomatic seizures in sub-Saharan Africa is more than twice that in high-income countries. However, most studies of acute symptomatic seizures from Africa are based on hospital samples or do not conduct surveys in demographic surveillance systems, which underestimates the burden. It is difficult to differentiate between febrile seizures and acute symptomatic seizures in Africa, especially in malaria-endemic areas where malaria parasites can sequester in the brain microvasculature; but this challenge can be addressed by robust identification of underlying causes. The proportion of complex acute symptomatic seizures (i.e., seizures that are focal, repetitive, or prolonged) in Africa are twice that reported in other parts of the world (>60% vs. ∼30%), which is often attributed to falciparum malaria. These complex phenotypes of acute symptomatic seizures can be associated with behavioral and emotional problems in high-income countries, and outcomes may be even worse in Africa. One Kenyan study reported behavioral and emotional problems in approximately 10% of children admitted with acute symptomatic seizures, but it is not clear whether the behavioral and emotional problems were due to the seizures, shared genetic susceptibility, etiology, or underlying neurological damage. The underlying neurological damage in acute symptomatic seizures can lead not only to behavioral and emotional problems but also to neurocognitive impairment and epilepsy. Electroencephalography may have a prognostic role in African children with acute symptomatic seizures. There are significant knowledge gaps regarding acute symptomatic seizures in Africa, which results in lack of reliable estimates for planning interventions. Future epidemiological studies of acute symptomatic seizures should be set up in Africa.

Prophylactic drug management for febrile seizures in children

BACKGROUND

Febrile seizures occurring in a child older than one month during an episode of fever affect 2% to 4% of children in Great Britain and the United States and recur in 30%. Rapid-acting antiepileptics and antipyretics given during subsequent fever episodes have been used to avoid the adverse effects of continuous antiepileptic drugs.

OBJECTIVES

To evaluate primarily the effectiveness and safety of antiepileptic and antipyretic drugs used prophylactically to treat children with febrile seizures; but also to evaluate any other drug intervention where there was a sound biological rationale for its use.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2016, Issue 7); MEDLINE (1966 to July 2016); Embase (1966 to July 2016); Database of Abstracts of Reviews of Effectiveness (DARE) (July 2016). We imposed no language restrictions. We also contacted researchers in the field to identify continuing or unpublished studies.

SELECTION CRITERIA

Trials using randomised or quasi-randomised participant allocation that compared the use of antiepileptic, antipyretic or other plausible agents with each other, placebo or no treatment.

DATA COLLECTION AND ANALYSIS

Two review authors (RN and MO) independently applied predefined criteria to select trials for inclusion and extracted the predefined relevant data, recording methods for randomisation, blinding and exclusions. For the 2016 update a third author (MC) checked all original inclusions, data analyses, and updated the search. Outcomes assessed were seizure recurrence at 6, 12, 18, 24, 36, and 48 months and at age 5 to 6 years in the intervention and non-intervention groups, and adverse medication effects. We assessed the presence of publication bias using funnel plots.

MAIN RESULTS

We included 40 articles describing 30 randomised trials with 4256 randomised participants. We analysed 13 interventions of continuous or intermittent prophylaxis and their control treatments. Methodological quality was moderate to poor in most studies. We found no significant benefit for intermittent phenobarbitone, phenytoin, valproate, pyridoxine, ibuprofen or zinc sulfate versus placebo or no treatment; nor for diclofenac versus placebo followed by ibuprofen, acetaminophen or placebo; nor for continuous phenobarbitone versus diazepam, intermittent rectal diazepam versus intermittent valproate, or oral diazepam versus clobazam.There was a significant reduction of recurrent febrile seizures with intermittent diazepam versus placebo or no treatment, with a risk ratio (RR) of  0.64 (95% confidence interval (CI) 0.48 to 0.85 at six months), RR of 0.69 (95% CI 0.56 to 0.84) at 12 months, RR 0.37 (95% CI 0.23 to 0.60) at 18 months, RR 0.73 (95% CI 0.56 to 0.95) at 24 months, RR 0.58 (95% CI 0.40 to 0.85) at 36 months, RR 0.36 (95% CI 0.15 to 0.89) at 48 months, with no benefit at 60 to 72 months. Phenobarbitone versus placebo or no treatment reduced seizures at 6, 12 and 24 months but not at 18 or 72 month follow-up (RR 0.59 (95% CI 0.42 to 0.83) at 6 months; RR 0.54 (95% CI 0.42 to 0.70) at 12 months; and RR 0.69 (95% CI 0.53 to 0.89) at 24 months). Intermittent clobazam compared to placebo at six months resulted in a RR of 0.36 (95% CI 0.20 to 0.64), an effect found against an extremely high (83.3%) recurrence rate in the controls, which is a result that needs replication.The recording of adverse effects was variable. Lower comprehension scores in phenobarbitone-treated children were found in two studies. In general, adverse effects were recorded in up to 30% of children in the phenobarbitone-treated group and in up to 36% in benzodiazepine-treated groups. We found evidence of publication bias in the meta-analyses of comparisons for phenobarbitone versus placebo (eight studies) at 12 months but not at six months (six studies); and valproate versus placebo (four studies) at 12 months, with too few studies to identify publication bias for the other comparisons.Most of the reviewed antiepileptic drug trials are of a methodological quality graded as low or very low. Methods of randomisation and allocation concealment often do not meet current standards; and treatment versus no treatment is more commonly seen than treatment versus placebo, leading to obvious risks of bias. Trials of antipyretics and zinc were of higher quality.

AUTHORS' CONCLUSIONS

We found reduced recurrence rates for children with febrile seizures for intermittent diazepam and continuous phenobarbitone, with adverse effects in up to 30%. Apparent benefit for clobazam treatment in one trial needs to be replicated to be judged reliable. Given the benign nature of recurrent febrile seizures, and the high prevalence of adverse effects of these drugs, parents and families should be supported with adequate contact details of medical services and information on recurrence, first aid management and, most importantly, the benign nature of the phenomenon.

Association of Interleukin-1 Gene Cluster and Interleukin-1 Receptor Polymorphisms With Febrile Seizures

Interleukin-1 (IL-1) plays a key role in inflammation, has an effect on a wide variety of cells, and often leads to tissue destruction. While the ratio between IL-1 and IL-1Ra could influence the development of different diseases of the central nervous system, its gene polymorphisms were investigated in a group of patients with febrile seizures. Ninety patients with febrile seizures were enrolled and compared with 140 controls. The allele and genotype frequency of single nucleotide polymorphisms within the IL-1α, β, IL-1 R and IL-1Ra gene were determined. The frequency of the IL-1Ra/C allele at position Mspa-I 11100 was decreased significantly (P= .002) and the IL-1Ra/T frequency was significantly increased in patients (P= .002). In addition, the CT genotype frequency at the same position was significantly overrepresented in controls compared to patients (P= .001). Certain alleles and genotypes in the IL-1 gene were overrepresented in patients with febrile seizures, which possibly could predispose individuals to this disease.

Single nucleotide polymorphisms of TNF-Α gene in febrile seizures

Febrile seizures (FS) is the most common seizure disorder during childhood. This study was performed in 78 patients with FS and 137 control subjects to assess polymorphisms of the TNF-α gene at positions -308 and -238, using the polymerase chain reaction and the sequence specific primers method. The highest positive allelic association that made the patients susceptible to FS was seen for TNF-α -238/G (p<0.0001). The GG genotype at TNF-α -238 was significantly higher in the patients with FS, compared to the controls (p=0.0001). Also, GA genotype at the same position was significantly lower in patients than in controls (P=0.0001). The GG haplotype had a significant positive association at TNF-α (308, 238) while GA haplotype showed a negative association (P<0.001). Our data support the idea that TNF-α single-nucleotide polymorphisms play a role in the pathogenesis of FS.

Sudden infant death syndrome, sleep, and seizures

benign febrile seizures seen in 7% of infants before 6 months play a role in the terminal pathway in a subset of sudden infant death syndrome victims. Supporting evidence: (1) lack of 5-hydroxitryptamine, one consistent finding in sudden infant death syndrome that Kinney et al coined a developmental serotonopathy, is consistent with risk for seizures. (2) Non-rapid eye movement sleep increasing during the age of highest risk for sudden infant death syndrome facilitates some seizures (seizure gate). (3) Sudden unexpected death in epilepsy is associated with severe hypoxemia and hypercapnia during postictal generalized electroencephalographic (EEG) suppression. In toddlers, sudden unexplained deaths are associated with hippocampal abnormalities and some seizures. (4) The sudden nature of both deaths warrants an exploration of similarities in the terminal pathway. Moreover, sudden infant death syndrome, febrile seizures, sudden unexplained death in childhood, and sudden unexpected death in epilepsy share some of the following risk factors: prone sleeping, infections, hyperthermia, preterm birth, male gender, maternal smoking, and mutations in genes that regulate sodium channels. State-of-the-art molecular studies can be exploited to test this hypothesis.

Association of TGFB, but not IL10, single nucleotide polymorphisms with febrile seizures

PURPOSE

Febrile seizures (FS) are the most common convulsive event in children. Inflammatory elements and genetics seem to have major roles in their pathogenesis.

METHODS

Seventy nine patients with FS were enrolled in this study and compared with 140 controls. Cytokine genotyping was performed, using polymerase chain reaction with sequence-specific primers. The allele and genotype frequency of three single nucleotide polymorphisms (SNPs) within the IL-10 gene at -1082, -819 and -592 positions (rs1800896, rs1800871, rs1800872), and two SNPs within the TGFB at codons 10 and 25 (rs1982037, rs1800471) were determined.

RESULTS

No significant difference was detected in allelic frequency of IL-10 at -1082, -819 and -592 positions (rs1800896, rs1800871, rs1800872) and TGFB at codon 25 (rs1800471), between patients and controls. A significant negative association was observed at the codon 10/CT (rs1982037) in the patient group (OR, 0.5; 95%CI, 0.27-0.93; p=0.026). Further, a negative association was detected in patients with simple FS at same position (OR, 0.41; 95%CI, 0.18-0.93; p=0.03), thus revealing a protective effects in FS patients. There was no significant difference in allelic and genotype frequency between simple and complex FS samples. Furthermore, haplotype analysis revealed significant difference in frequency of TGFB/TC haplotype in comparison between complex FS patients and controls (p=0.048).

CONCLUSION

Certain alleles, genotypes, and haplotypes in TGFB genes were over represented in patients with FS, which possibly could predispose individuals to this disease.

Association of IL4 single-nucleotide polymorphisms with febrile seizures

As of importance of interleukin-4 (IL-4) in inhibiting the production of proinflammatory cytokines, the IL4 gene polymorphisms were investigated in patients with febrile seizure. This association has not been investigated yet, except 1 study which has been done in Japanese population. Eighty-two patients with febrile seizure were enrolled in this study, compared with 139 controls. The allele and genotype frequency of 3 single-nucleotide polymorphisms of IL4 gene were determined. Frequency of the IL4-590/C allele in the patient group was significantly higher than in the control group (P < .0001). Frequency of the following genotypes was significantly lower in patients compared to controls: IL-4 (-590) TC (P = .0001) and IL-4 (-33) TC (P = .001). The most frequent IL-4 haplotype in the patient group was TCC (P = .00) haplotype. In contrast, frequencies of GCC (P = .01), TTT (P = .009), and TTC (P = .0007) haplotypes were significantly lower in febrile seizure patients. Certain alleles, genotypes, and haplotypes in the IL4 gene were overrepresented in Iranian patients with febrile seizure, which could predispose individuals to this disease, and further investigations in other ethnicities are required.

Deficiency of very large G-protein-coupled receptor-1 is a risk factor of tumor-related epilepsy: a whole transcriptome sequencing analysis

The majority of patients with low-grade glioma (LGG) experience epileptic seizures as their initial symptom, while the underlying mechanisms of tumor-related seizures are still far from being fully understood. In addition to tumor type and location, genetic changes of LGGs are considered to be influential factors in causing epileptic seizures. Nevertheless, the molecular biomarkers associated with tumor-related epilepsy have rarely been identified. RNA sequence data from 80 patients with histologically confirmed LGG were collected from the Chinese glioma genome atlas database and significant differences in expression levels of 33 genes were found. One of the genes, Very large G-protein-coupled receptor-1 (VLGR1), had been previously associated with seizures. Therefore, we investigated the association between LGG-related epilepsy and VLGR1, which played a role in idiopathic epilepsy. The level of VLGR1 expression was compared between patients with epileptic seizures and those without using the reads per kilobase transcriptome per million method. To evaluate the prognostic role of VLGR1 gene expression, the progression-free survival was determined by the Kaplan-Meier method and a multivariate Cox model. We demonstrated that VLGR1 had a significantly lower expression level in patients with epileptic seizures compared to seizure-free patients (p = 0.003). Furthermore, VLGR1 was highly associated with the presence of seizures in a multivariate statistical model. However, VLGR1 could not serve as an independent prognostic factor to determine progression-free survival of LGG patients. Based on RNA sequence data analysis, our results suggest that low expression of VLGR1 is a significant risk factor of epileptic seizures in patients with LGG.

Clinical characteristics of seizures associated with viral gastroenteritis in children

OBJECTIVE

We analyzed the clinical features of seizures during gastroenteritis in children by comparing the norovirus and rotavirus pathogen, and the impact of fever, if present, during the seizure episodes.

METHODS

Retrospective analysis was performed on 293 consecutive pediatric patients admitted with viral gastroenteritis to Osaka General Hospital between November 2007 and May 2009. Eighteen patients developed seizures, 12 of whom were positive for norovirus and six for rotavirus, as revealed by antigen detection. Of these 18 seizure patients, eight presented without fever (the aFS group) and 10 presented with febrile episodes (FS group).

RESULTS

Seizure patients in the rotavirus group (83%) were more likely to be febrile than those in the norovirus group (58%). Compared with the aFS group, 90% of patients in the FS group presented seizures at an early stage of gastroenteritis. The frequency of clustered seizures in the FS group was considerably higher than that of febrile seizures in general and was also as high as that of "convulsions with mild gastroenteritis (CwG)". All seizure patients, whether febrile or afebrile, presented with generalized tonic clonic seizures (GTCS), complex partial seizures (CPS), or both. Diazepam (DZP) was less effective and carbamazepine (CBZ) was completely effective for the cessation of seizures in the FS group, similar to the drug response observed in CwG.

CONCLUSIONS

The causative pathogen (norovirus or rotavirus) affected the frequency of febrile episodes during gastroenteritis, but fever had little effect on the clinical features of seizures. However, seizures occurred earlier during gastroenteritis in the FS group. On the whole, the clinical features of febrile seizures during viral gastroenteritis may closely resemble those of "convulsions with mild gastroenteritis" (CwG) than those of febrile seizures in general with respect to the frequency of clustered seizures and the antiepileptic drug responses and may have a pathogenic mechanism distinct from those of febrile seizures due to other causes.

Serum interleukin-1beta and tumor necrosis factor-alpha in febrile seizures: is there a link?

Purpose

Febrile seizures are induced by fever and are the most common type of seizures in children. Although numerous studies have been performed on febrile seizures, their pathophysiology remains unclear. Recent studies have shown that cytokines may play a role in the pathogenesis of febrile seizures. The present study was conducted to identify potential links between serum interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and febrile seizures.

Methods

Ninety-two patients with simple or complex febrile seizures (46 patients per seizure type), and 46 controls with comparable age, sex, and severity of temperature were enrolled.

Results

The median concentrations of serum IL-1β in the simple, complex febrile seizure, and control groups were 0.05, 0.1, and 0.67 pg/mL, respectively (P=0.001). Moreover, the median concentrations of TNF-α in the simple, complex febrile seizure, and control groups were 2.5, 1, and 61.5 pg/mL, respectively (P=0.001). Furthermore, there were significant differences between the case groups in serum IL-1β and TNF-α levels (P<0.05).

Conclusion

Unlike previous studies, our study does not support the hypothesis that increased IL-1β and TNF-α production is involved in the pathogenesis of febrile seizures.

Recent advances in febrile seizures

Febrile seizures are the most common seizures of childhood. A family history of febrile seizures is common, and the disorder is genetically heterogenous. While guidelines are available for management of simple febrile seizures, the management of complex febrile seizures is individualised. After a febrile seizure, it is important to rule out CNS infection and the decision to perform a lumbar puncture should be based on the clinical condition of the child. Neuroimaging and EEG are not required immediately in workup for simple or complex febrile seizures. Recurrence of febrile seizures may be managed at home by the parents with benzodiazepines. If the recurrences are multiple or prolonged and parents are unable to give home treatment, intermittent benzodiazepine prophylaxis may be given. Continuous antiepileptic prophylaxis may be given only to the children where intermittent prophylaxis has failed. Febrile seizures are also associated with increased risk of epilepsy, but this cannot be prevented by any form of treatment. There is also an increased risk of mesial temporal sclerosis, but whether this is an effect or cause of febrile seizures is as yet unclear. There is no increase in neurological handicaps or mortality following febrile seizures.

Association of IL6 single nucleotide polymorphisms with febrile seizures

Febrile seizures (FSs) are the most common convulsive event in children. Inflammatory elements and genetics have major roles in their pathogenesis. As of the importance of interleukin-6 (IL-6) in FS, this study was performed to assess IL6 single nucleotide polymorphisms (SNPs) in a group of patients with FS. IL6 gene (-174 and +565) SNPs were studied on genomic DNAs of 90 children with FS, using PCR-SSP method. The results were compared to 139 healthy individuals. The presence of the G allele or the GG genotype at +565 position reduced risk of FS, while the A allele at +565 position of the promoter regions was a constituted risk factor for developing FS. This study could support the idea that IL6 SNPs play a role in the pathogenesis of FS.

Soy infant formula and seizures in children with autism: a retrospective study

Seizures are a common phenotype in many neurodevelopmental disorders including fragile X syndrome, Down syndrome and autism. We hypothesized that phytoestrogens in soy-based infant formula were contributing to lower seizure threshold in these disorders. Herein, we evaluated the dependence of seizure incidence on infant formula in a population of autistic children. Medical record data were obtained on 1,949 autistic children from the SFARI Simplex Collection. An autism diagnosis was determined by scores on the ADI-R and ADOS exams. The database included data on infant formula use, seizure incidence, the specific type of seizure exhibited and IQ. Soy-based formula was utilized in 17.5% of the study population. Females comprised 13.4% of the subjects. There was a 2.6-fold higher rate of febrile seizures [4.2% versus 1.6%, OR = 2.6, 95% CI = 1.3–5.3], a 2.1-fold higher rate of epilepsy comorbidity [3.6% versus 1.7%, OR = 2.2, 95% CI = 1.1–4.7] and a 4-fold higher rate of simple partial seizures [1.2% versus 0.3%, OR = 4.8, 95% CI = 1.0–23] in the autistic children fed soy-based formula. No statistically significant associations were found with other outcomes including: IQ, age of seizure onset, infantile spasms and atonic, generalized tonic clonic, absence and complex partial seizures. Limitations of the study included: infant formula and seizure data were based on parental recall, there were significantly less female subjects, and there was lack of data regarding critical confounders such as the reasons the subjects used soy formula, age at which soy formula was initiated and the length of time on soy formula. Despite these limitations, our results suggest that the use of soy-based infant formula may be associated with febrile seizures in both genders and with a diagnosis of epilepsy in males in autistic children. Given the lack of data on critical confounders and the retrospective nature of the study, a prospective study is required to confirm the association.

Proinflammatory and anti-inflammatory cytokines in febrile seizures and epilepsy: systematic review and meta-analysis

Activation of proinflammatory and anti-inflammatory cytokines network seems to have a role in febrile seizures (FS). The present meta-analysis was aimed to pool the inconsistent data provided with case-control studies on the relationship of proinflammatory and anti-inflammatory cytokines and FS/epilepsy risk. The genotype interleukin (IL)-1α-889 1/1 (recessive model) was significantly correlated with increased risk of epilepsy (p=0.008) and FS/epilepsy (p=0.004). Patients with IL-1β-511 T/T homozygote were more susceptible to develop FS (p=0.036) but not epilepsy. Furthermore, the T/T genotype was totally associated with increased risk of FS/epilepsy (p=0.043). Although the recessive model was also confirmed for the Asian subgroup (FS and FS/epilepsy), we found a protective effect of C/C genotype toward developing FS in the Caucasian race (p=0.020). The second meta-analysis on cytokine levels showed a statistically higher serum level of IL-6 in patients with epilepsy compared to control subjects without epilepsy. The present meta-analysis showed that two alleles of proinflammatory cytokines (IL-1α-889 and IL-1β-511) in addition to the serum concentration of IL-6 were significantly associated with FS and epilepsy or both in various subgroup analyses.

A Clinical-EEG Study of Sleepiness and Psychological Symptoms in Pharmacoresistant Epilepsy Patients Treated with Lacosamide

Our aim was to evaluate the EEG and clinical modifications induced by the new antiepileptic drug lacosamide (LCM) in patients with epilepsy. We evaluated 10 patients affected by focal pharmacoresistant epilepsy in which LCM (mean 250 mg/day) was added to the preexisting antiepileptic therapy, which was left unmodified. Morning waking EEG recording was performed before (t0) and at 6 months (t1) after starting LCM. At t0 and t1, patients were also administered questionnaires evaluating mood, anxiety, sleep, sleepiness, and fatigue (Beck Depression Inventory; State-Trait Anxiety Inventory Y1 and Y2; Pittsburgh Sleep Quality Index; Epworth Sleepiness Scale; Fatigue Severity Scale). We performed a quantitative analysis of EEG interictal abnormalities and background EEG power spectrum analysis. LCM as an add-on did not significantly affect anxiety, depression, sleepiness, sleep quality, and fatigue scales. Similarly, adding LCM to preexisting therapy did not modify significantly patient EEGs in terms of absolute power, relative power, mean frequency, and interictal abnormalities occurrence. In conclusion, in this small cohort of patients, we confirmed that LCM as an add-on does not affect subjective parameters which play a role, among others, in therapy tolerability, and our clinical impression was further supported by evaluation of EEG spectral analysis.

The genetic risk of acute seizures in African children with falciparum malaria

PURPOSE

It is unclear why some children with falciparum malaria develop acute seizures and what determines the phenotype of seizures. We sought to determine if polymorphisms of malaria candidate genes are associated with acute seizures.

METHODS

Logistic regression was used to investigate genetic associations with malaria-associated seizures (MAS) and complex MAS (repetitive, prolonged, or focal seizures) in four MalariaGEN African sites, namely: Blantyre, Malawi; Kilifi, Kenya; Kumasi, Ghana; and Muheza, Tanzania. The analysis was repeated for five inheritance models (dominant, heterozygous, recessive, additive, and general) and adjusted for potential confounders and multiple testing.

KEY FINDINGS

Complex phenotypes of seizures constituted 71% of all admissions with MAS across the sites. MAS were strongly associated with cluster of differentiation-ligand-rs3092945 in females in Kilifi (p = 0.00068) and interleukin (IL)-17 receptor E-rs708567 in the pooled analysis across the sites (p = 0.00709). Complex MAS were strongly associated with epidermal growth factor module-containing mucin-like hormone receptor (EMR)1-rs373533 in Kumasi (p = 0.00033), but none in the pooled analysis. Focal MAS were strongly associated with IL-20 receptor A-rs1555498 in Muheza (p = 0.00016), but none in the pooled analysis. Prolonged MAS were strongly associated with complement receptor 1-rs17047660 in Kilifi (p = 0.00121) and glucose-6-phosphate dehydrogenase-rs1050828 in females in the pooled analysis (p = 0.00155). Repetitive MAS were strongly associated with EMR1-rs373533 in Kumasi (p = 0.00003) and cystic fibrosis transmembrane conductance receptor-rs17140229 in the pooled analysis (p = 0.00543). MAS with coma/cerebral malaria were strongly associated with EMR1-rs373533 in Kumasi (p = 0.00019) and IL10-rs3024500 in the pooled analysis across the sites (p = 0.00064).

SIGNIFICANCE

We have identified a number of genetic associations that may explain the risk of seizures in >2,000 cases admitted to hospitals with MAS across four sites in Africa. These associations differed according to phenotype of seizures and site.

Risk factors for autistic regression: results of an ambispective cohort study

A subgroup of children diagnosed with autism experience developmental regression featured by a loss of previously acquired abilities. The pathogeny of autistic regression is unknown, although many risk factors likely exist. To better characterize autistic regression and investigate the association between autistic regression and potential influencing factors in Chinese autistic children, we conducted an ambispective study with a cohort of 170 autistic subjects. Analyses by multiple logistic regression showed significant correlations between autistic regression and febrile seizures (OR = 3.53, 95% CI = 1.17-10.65, P = .025), as well as with a family history of neuropsychiatric disorders (OR = 3.62, 95% CI = 1.35-9.71, P = .011). This study suggests that febrile seizures and family history of neuropsychiatric disorders are correlated with autistic regression.

High temperatures alter physiological properties of pyramidal cells and inhibitory interneurons in hippocampus

Temperature has multiple effects on neurons, yet little is known about the effects of high temperature on the physiology of mammalian central neurons. Hyperthermia can influence behavior and cause febrile seizures. We studied the effects of acute hyperthermia on the immature hippocampus in vitro by recording from pyramidal neurons and inhibitory oriens-lacunosum moleculare (O-LM) interneurons (identified by green fluorescent protein (GFP) expression in the GIN mouse line). Warming to 41°C caused depolarization, spontaneous action potentials, reduced input resistance and membrane time constant, and increased spontaneous synaptic activity of most pyramidal cells and O-LM interneurons. Pyramidal neurons of area CA3 were more strongly excited by hyperthermia than those of area CA1. About 90% of O-LM interneurons in both CA1 and CA3 increased their firing rates at hyperthermic temperatures; interneurons in CA3 fired faster than those in CA1 on average. Blockade of fast synaptic transmission did not abolish the effect of hyperthermia on neuronal excitability. Our results suggest that hyperthermia increases hippocampal excitability, particularly in seizure-prone area CA3, by altering the intrinsic membrane properties of pyramidal cells and interneurons.

Comparison of serum zinc levels measured by inductively coupled plasma mass spectrometry in preschool children with febrile and afebrile seizures

Background

Changes in levels of trace elements have been proposed to underlie febrile seizures. Particularly, low zinc levels have been proposed as related factor of febrile seizure. In this study, we investigated whether mean serum zinc levels differed between children with febrile seizure and afebrile seizure.

Methods

Using inductively coupled plasma mass spectrometry, serum zinc levels were measured in 288 children who had been diagnosed with febrile seizures (N=248) and afebrile seizures (N=40). Mean serum zinc levels were compared between the 2 groups.

Results

Mean serum zinc level was 60.5±12.7 µg/dL in the febrile seizure group and 68.9 ±14.5 µg/dL in the afebrile seizure group. A significant difference in serum zinc levels was observed between the febrile and afebrile seizure groups (P<0.001).

Conclusions

Zinc levels in children with febrile seizure were significantly lower than those in children with afebrile seizure.

Inheritance of febrile seizures in sudden unexplained death in toddlers

Sudden unexplained death in toddlers has been associated with febrile seizures, family history of febrile seizures, and hippocampal anomalies. We investigated the mode of inheritance for febrile seizures in these families. A three-generation pedigree was obtained from families enrolled in the San Diego Sudden Unexplained Death in Childhood Research Project, involving toddlers with sudden unexplained death, febrile seizures, and family history of febrile seizures. In our six cases, death was unwitnessed and related to sleep. The interval from last witnessed febrile seizure to death ranged from 3 weeks to 6 months. Hippocampal abnormalities were identified in one of three cases with available autopsy sections. Autosomal dominant inheritance of febrile seizures was observed in three families. A fourth demonstrated autosomal dominant inheritance with incomplete penetrance or variable expressivity. In two families, the maternal and paternal sides manifested febrile seizures. In this series, the major pattern of inheritance in toddlers with sudden unexplained death and febrile seizures was autosomal dominant. Future studies should develop markers (including genetic) to identify which patients with febrile seizures are at risk for sudden unexplained death in childhood, and to provide guidance for families and physicians.

Evaluation of candidate genes from orphan FEB and GEFS+ loci by analysis of human brain gene expression atlases

Febrile seizures, or febrile convulsions (FEB), represent the most common form of childhood seizures and are believed to be influenced by variations in several susceptibility genes. Most of the associated loci, however, remain ‘orphan’, i.e. the susceptibility genes they contain still remain to be identified. Further orphan loci have been mapped for a related disorder, genetic (generalized) epilepsy with febrile seizures plus (GEFS+).

We show that both spatially mapped and ‘traditional’ gene expression data from the human brain can be successfully employed to predict the most promising candidate genes for FEB and GEFS+, apply our prediction method to the remaining orphan loci and discuss the validity of the predictions. For several of the orphan FEB/GEFS+ loci we propose excellent, and not always obvious, candidates for mutation screening in order to aid in gaining a better understanding of the genetic origin of the susceptibility to seizures.

Epilepsy genetics--past, present, and future

Human epilepsy is a common and heterogeneous condition in which genetics play an important etiological role. We begin by reviewing the past history of epilepsy genetics, a field that has traditionally included studies of pedigrees with epilepsy caused by defects in ion channels and neurotransmitters. We highlight important recent discoveries that have expanded the field beyond the realm of channels and neurotransmitters and that have challenged the notion that single genes produce single disorders. Finally, we project toward an exciting future for epilepsy genetics as large-scale collaborative phenotyping studies come face to face with new technologies in genomic medicine.

Correlation between serum selenium level and febrile seizures

Febrile seizures are the most common form of childhood seizures. Although the literature associates certain micronutrients with febrile seizures, there is limited information about the effects of such micronutrients. This study aimed to determine the relationship between serum selenium level and simple febrile seizures in children. This case-control study was conducted in the Children's Hospital in Qazvin, Iran, in 2008. The serum selenium level of 30 children who experienced simple febrile seizures (case group) was measured and compared with that of 30 febrile children without seizure (control group). The serum selenium level was measured by flame atomic absorption spectrophotometer. Data were analyzed by using t-test. Mean ± standard deviation of serum selenium level in the case and control groups was 44.4 ± 10.9 and 63 ± 9.78 μg/dL, a significant difference (P < 0.001). In the case group, 18/30 patients (60%) had a serum selenium level below the norm of 46 μg/dL, whereas serum selenium level in the entire control group was within the normal range (P < 0.01). The serum selenium level in the children who had simple febrile seizures was significantly lower than in the nonseizure control group. It seems that there is an association between serum selenium deficiency and simple febrile seizures; however, further study is recommended.

Milder phenotype with SCN1A truncation mutation other than SMEI

Till now truncation mutations of voltage-gated sodium channel alpha subunit type I (SCN1A) gene were mostly found in severe myoclonic epilepsy of infancy (SMEI) patients. In this research we first identified two novel de novo truncation mutations (S662X and M145fx148) in two patients whose phenotypes were quite milder compared with SMEI patients. One patient was diagnosed as generalized epilepsy with febrile seizures plus (GEFS+); the other had focal seizures. Both patients had good response to anti-epileptic therapy (valproate or the combination of valproate and topiramate). Our findings extended the utility of the SCN1A gene testing and further confirmed the complex relationship between genotype and phenotype of SCN1A mutations. Further work is needed to optimize the protocol for specific genetic testing in children with epilepsy.

Suggestive evidence for a new locus for epilepsy with heterogeneous phenotypes on chromosome 17q

PURPOSE

To characterize the clinical features and molecular genetic background in a family with various epilepsy phenotypes including febrile seizures, childhood absence epilepsy, and possible temporal lobe epilepsy.

METHODS

Clinical data were collected. DNA and RNA were extracted from peripheral blood. A genome-wide microsatellite marker scan was performed and regions with a multipoint location score > or =1.5 were fine mapped. Functional candidate genes identified from databases and by comparing gene expression profiles of genes between affected and unaffected individuals were sequenced. Copy number variation was evaluated with array-based comparative genomic hybridization.

RESULTS

The seizure phenotype was benign. Inheritance was consistent with an autosomal dominant model and reduced penetrance. The highest two-point LOD score of 2.8 was identified at marker D17S1606 in a 37cM interval on chromosome 17q12-q24. Loci on 5q11.2 and on 18p11-q11, showed LOD scores > or =1.5 after fine mapping. Sequencing of nine ion-channel genes and two (RPIP8 and SLC25A39) differentially expressed genes from 17q12-q24, as well as IMPA2 from 18p11-q11 did not reveal a pathogenic alteration. No clinically relevant copy number variation was identified.

CONCLUSIONS

Our findings suggest complex inheritance of seizure susceptibility in the family with contribution from three loci, including a possible new locus on chromosome 17q. The underlying molecular defects remain unknown.

Novel susceptibility locus at chromosome 6q16.3-22.31 in a family with GEFS+

BACKGROUND

Genetic epilepsy with febrile seizures plus (GEFS+) is a familial epilepsy syndrome with extremely variable expressivity. Mutations in 5 genes that raise susceptibility to GEFS+ have been discovered, but they account for only a small proportion of families.

METHODS

We identified a 4-generation family containing 15 affected individuals with a range of phenotypes in the GEFS+ spectrum, including febrile seizures, febrile seizures plus, epilepsy, and severe epilepsy with developmental delay. We performed a genome-wide linkage analysis using microsatellite markers and then saturated the potential linkage region identified by this screen with more markers. We evaluated the evidence for linkage using both model-based and model-free (posterior probability of linkage [PPL]) analyses. We sequenced 16 candidate genes and screened for copy number abnormalities in the minimal genetic region.

RESULTS

All 15 affected subjects and 1 obligate carrier shared a haplotype of markers at chromosome 6q16.3-22.31, an 18.1-megabase region flanked by markers D6S962 and D6S287. The maximum multipoint lod score in this region was 4.68. PPL analysis indicated an 89% probability of linkage. Sequencing of 16 candidate genes did not reveal a causative mutation. No deletions or duplications were identified.

CONCLUSIONS

We report a novel susceptibility locus for genetic epilepsy with febrile seizures plus at 6q16.3-22.31, in which there are no known genes associated with ion channels or neurotransmitter receptors. The identification of the responsible gene in this region is likely to lead to the discovery of novel mechanisms of febrile seizures and epilepsy.

Sudden death, febrile seizures, and hippocampal and temporal lobe maldevelopment in toddlers: a new entity

Recently, we reported hippocampal and temporal lobe abnormalities in 5 toddlers with sudden unexplained death in childhood (SUDC). The association of these anomalies with a high incidence (40%) of individual/family histories of simple febrile seizures in the cases raised concern that febrile seizures can be associated with death. In a series of 64 toddlers with sudden death, we tested the hypothesis that an SUDC subset is characterized by hippocampal and temporal lobe maldevelopment and an individual and/or family history of simple familial seizures. Cases of sudden and unexplained death in children aged 1.0 to 5.9 years (median 1.7 years) were divided into groups based upon a history of febrile or nonfebrile seizures, familial febrile seizures, and autopsy classification of cause of death. Forty-nine of the 64 cases (77%) were classified as SUDC, of which 40% had an individual/family history of febrile seizures. Of the 26 SUDC cases with available hippocampal sections, 62% (16/26) had hippocampal and temporal lobe anomalies, including 82% (9/11) of cases with an individual/family history of febrile seizures. Cases with these anomalies were all found dead during a sleep period, typically in the prone (87%) position. We conclude that a potential new entity may account for the majority of SUDC in toddlers, defined by sleep-related death in the prone position, individual/family history of febrile seizures, and hippocampal and temporal lobe anomalies. The mechanism of death appears analogous to sudden death in (temporal lobe) epilepsy, with a putative unwitnessed seizure during sleep leading to airway occlusion and death. This study mandates further research into the potential link between simple febrile seizures and death.

Inflammation in rat pups subjected to short hyperthermic seizures enhances brain long-term excitability

Inflammatory processes in response to infection are involved in the pathophysiological mechanisms of febrile seizures (FS). Prolonged FS may promote the development of temporal lobe epilepsy. It has been shown in rats that prolonged hyperthermic seizures (HS) are followed by long-term modification of brain excitability. To examine whether short FS results in modification of brain excitability, we induced an inflammatory response in combination with short HS.

METHODS

HS were induced in rat pups at either P11 or P16 using a heating lamp with a continuous monitoring of the core temperature. Rat pups were maintained at the temperature seizure threshold during 5 min. In order to induce an inflammatory response, lipopolysaccharide (LPS, Eschericha coli 055:B5) was injected i.p. at 5 microg/kg or 50 microg/kg, 2h prior seizure induction. After 1 month, pentylenetetrazol threshold (PTZth) was used to assess the change of brain excitability. Histological studies were performed 24h after the FS (Fluorojade-B) and after the PTZth (cresyl violet).

RESULTS

The temperature thresholds to induce the seizures were not different among the groups. The PTZth was not significantly different between sham and FS only groups, and decreased dose-dependently when LPS was combined to FS. Histological studies suggested the absence of cell injury.

CONCLUSION

Lower PTZth obtained by using LPS in combination with HS in rat pups suggests a change in brain excitability. Our model with only 5 min of HS in combination with LPS suggests that an inflammatory response could, in part, explain long-term change in brain excitability following short FS.

The role of interleukin-1beta in febrile seizures

Febrile seizures (FS) occur in children as a result of fever. Despite their prevalence, the pathophysiology of FS has remained unclear. Recent evidence from clinical and experimental studies has highlighted a potential role of immune generated products in the genesis of FS. Of particular interest are the pro-inflammatory cytokine, interleukin-1beta (IL-1beta) and its naturally occurring antagonist, interleukin 1 receptor antagonist (IL-1ra). Using a novel animal model of FS, involving the generation of physiological fever, we investigated the role of the IL-1beta/IL-1ra system in the genesis of FS. We found that animals with FS had increased hippocampal and hypothalamic IL-1beta compared to equally treated animals without FS, which was first evident at onset of FS in the hippocampus. There were no differences in IL-1ra levels. ICV IL-1beta increased the number of animals with FS while IL-1ra had an opposite anti-convulsant effect. The data from these studies, in combination with recent results from other laboratories, have established a putative role for the IL-1beta/IL-1ra system in the genesis of FS.

The association between iron deficiency and febrile seizures in childhood

PURPOSE

The purpose of this study was to determine the association between iron deficiency and febrile seizures in a large cohort of children aged 6 to 36 months.

METHODS

A retrospective case control study with 361 patients who presented with febrile seizures to the emergency department and 390 otherwise healthy controls who presented with a febrile illness to the emergency department were reviewed to determine iron status using the MCV, RDW, and hemoglobin.

RESULTS

A total of 9% of cases had iron deficiency (ID) and 6% had iron deficiency anemia (IDA), compared to 5% and 4% of controls respectively. The conditional logistic regression odds ratio for ID in patients with febrile seizures was 1.84 (95% CI, 1.02-3.31).

CONCLUSION

Children with febrile seizures were almost twice as likely to be iron deficient as those with febrile illness alone. The results suggest that screening for ID should be considered in children presenting with febrile seizure.

Temperature- and age-dependent seizures in a mouse model of severe myoclonic epilepsy in infancy

Heterozygous loss-of-function mutations in the alpha subunit of the type I voltage-gated sodium channel Na(V)1.1 cause severe myoclonic epilepsy in infancy (SMEI), an infantile-onset epileptic encephalopathy characterized by normal development followed by treatment-refractory febrile and afebrile seizures and psychomotor decline. Mice with SMEI (mSMEI), created by heterozygous deletion of Na(V)1.1 channels, develop seizures and ataxia. Here we investigated the temperature and age dependence of seizures and interictal epileptiform spike-and-wave activity in mSMEI. Combined video-EEG monitoring demonstrated that mSMEI had seizures induced by elevated body core temperature but wild-type mice were unaffected. In the 3 age groups tested, no postnatal day (P)17-18 mSMEI had temperature-induced seizures, but nearly all P20-22 and P30-46 mSMEI had myoclonic seizures followed by generalized seizures caused by elevated core body temperature. Spontaneous seizures were only observed in mice older than P32, suggesting that mSMEI become susceptible to temperature-induced seizures before spontaneous seizures. Interictal spike activity was seen at normal body temperature in most P30-46 mSMEI but not in P20-22 or P17-18 mSMEI, indicating that interictal epileptic activity correlates with seizure susceptibility. Most P20-22 mSMEI had interictal spike activity with elevated body temperature. Our results define a critical developmental transition for susceptibility to seizures in SMEI, demonstrate that body temperature elevation alone is sufficient to induce seizures, and reveal a close correspondence between human and mouse SMEI in the striking temperature and age dependence of seizure frequency and severity and in the temperature dependence and frequency of interictal epileptiform spike activity.