New locus for febrile seizures with absence epilepsy on 3p and a possible modifier gene on 18p

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.

The genetics and molecular biology of fever-associated seizures or epilepsy

Fever-associated seizures or epilepsy (FASE) is primarily characterised by the occurrence of a seizure or epilepsy usually accompanied by a fever. It is common in infants and children, and generally includes febrile seizures (FS), febrile seizures plus (FS+), Dravet syndrome (DS) and genetic epilepsy with febrile seizures plus (GEFSP). The aetiology of FASE is unclear. Genetic factors may play crucial roles in FASE. Mutations in certain genes may cause a wide spectrum of phenotypical overlap ranging from isolated FS, FS+ and GEFSP to DS. Synapse-associated proteins, postsynaptic GABAA receptor, and sodium channels play important roles in synaptic transmission. Mutations in these genes may involve in the pathogenesis of FASE. Elevated temperature promotes synaptic vesicle (SV) recycling and enlarges SV size, which may enhance synaptic transmission and contribute to FASE occurring. This review provides an overview of the loci, genes, underlying pathogenesis and the fever-inducing effect of FASE. It may provide a more comprehensive understanding of pathogenesis and contribute to the clinical diagnosis of FASE.

Interleukin-6 gene polymorphisms in Egyptian children with febrile seizures: a case-control study

BACKGROUND

Febrile seizures are the most common form of childhood seizures. Among pro-inflammatory cytokines, interleukin-6 is the key acute-phase cytokine. To date, only a few studies concerned the association of interleukin-6 gene polymorphisms with febrile seizures.In this study, we aimed to investigate 3 cytokine single-nucleotide polymorphisms situated at positions -174 (G/C), -572 (G/C), and -597 (G/A) in the promoter region of the interleukin-6 gene for the first time in Egyptian children with febrile seizures.

METHODS

This was a case-control study included 100 patients with febrile seizure, and matched with age, gender, ethnicity 100 healthy control subjects. Interleukin-6 -174 (G/C), -572 (G/C), and -597 (G/A) polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while the serum IL6 levels were measured by ELISA method.

RESULTS

Compared to the controls subjects, the frequency of the -174 GG and -597 GG IL6 genotypes were observed to be increased in children with febrile seizures (OR: 4.17; 95 % CI: 1.86-9.49; P <0.01 and OR: 1.96; 95 % CI: 1.06-3.63;P <0.05, respectively). We found a significant positive association between the -597 GG genotype and susceptibility to complex febrile seizures as did the G allele at the same position (OR: 4.2; 95 % CI: 1.4-13.3 for the GG genotype; P <0.01) and (OR: 2.89; 95 % CI: 1.1-7.7 for the G allele; P <0.05 respectively). Our data revealed no association between IL6- genotypes and serum IL6 levels in patients with febrile seizures (P > 0.05).

CONCLUSION

In conclusion, our data brought a novel observation that the presence of a G allele or GG genotype at the -174 and the GG genotype at the -597 positions of the promoter region of the interleukin-6 gene constitute risk factors for developing febrile seizures in Egyptian children. Moreover, we observed a significant positive association between the IL6 -597 GG genotype and susceptibility to complex febrile seizures as did the G allele at the same position. However, we found no association between IL6- genotypes and serum IL6 levels in patients with febrile seizures.

Genetic background of febrile seizures

Febrile seizures (FSs) occur in children older than 1 month and without prior afebrile seizures in the absence of a central nervous system infection or acute electrolyte imbalance. Their pathogenesis is multifactorial. The most relevant familial studies evidence an occurrence rate ranging from 10% to 46% and median recurrence rate of 36% in children with positive familial history for FS. The main twin studies demonstrated a higher concordance rate in monozygotic twins with FS than in dizygotic ones. Linkage studies have proposed 11 chromosomal locations responsible to FS attributed to FEB1 to FEB11. Population-based association studies have shown at least one positive association for 14 of 41 investigated genes with FS. The proinflammatory cytokine interleukin 1β (IL-1β) was the most investigated and also gene associated with susceptibility to FS. A possible role in the overlapping of epilepsy and FS was found for 16 of 36 investigated genes. SCN1A, IL-1β, CHRNA4, and GABRG2 were the most commonly involved genes in this context. The genetic background of FS involves the regulation of different processes, including individual and familial susceptibility, modulation of immune response, and neuronal excitability and interactions with exogenous agents such as viruses.

Genetic generalized epilepsies

In the International League Against Epilepsy's most recent revision of classification and terminology, the term idiopathic epilepsy, previously used to describe those epilepsies whose cause was unknown, but presumed genetic, has been removed. It has been replaced by the term genetic epilepsy, only to be used to describe epilepsy in which the etiology has a known or presumed genetic defect in which seizures are the core symptom of the disorder. The purpose of this article was to review the electroclinical spectrum of those epilepsies that would fall under this new designation of genetic epilepsies in the context of specific generalized epilepsy syndromes providing an update in the clinical, electroencephalographic, and genetic findings in these syndromes.

Genetics of idiopathic epilepsies

One of the most exciting areas in epilepsy has been the explosion in our understanding of the genetics of the epilepsies over the last decade. Built on a long history of careful clinical genetic studies of the epilepsies, the relatively recent discovery of epilepsy genes has enabled insights into pathways causing seizure disorders. A variety of mutational mechanisms can cause epilepsy resulting from different, and sometimes surprising, molecular processes such as copy number variation within the genome. The majority of known epilepsy genes encode ion channel subunits leading many of the genetic epilepsies to be regarded as channelopathies. Understanding how dysfunction of a mutant protein leads to hyperexcitability is key to understanding the pathophysiology of this group of serious and common childhood disorders. The architecture of the common genetic epilepsies following complex inheritance, where multiple genes are involved, is also beginning to be unraveled. The clinical approach to understanding the genetics of the epilepsies has matured and requires a detailed family history of seizures together with delineation of the child's epilepsy syndrome. Recognition of specific genetic epilepsy syndromes enables optimal treatment and prognostic and genetic counseling.

A hot topic: temperature sensitive sodium channelopathies

Perturbations to body temperature affect almost all cellular processes and, within certain limits, results in minimal effects on overall physiology. Genetic mutations to ion channels, or channelopathies, can shift the fine homeostatic balance resulting in a decreased threshold to temperature induced disturbances. This review summarizes the functional consequences of currently identified voltage-gated sodium (NaV) channelopathies that lead to disorders with a temperature sensitive phenotype. A comprehensive knowledge of the relationships between genotype and environment is not only important for understanding the etiology of disease, but also for developing safe and effective treatment paradigms.

Genetics of temporal lobe epilepsy: a review

Temporal lobe epilepsy (TLE) is usually regarded as a polygenic and complex disorder. To understand its genetic component, numerous linkage analyses of familial forms and association studies of cases versus controls have been conducted since the middle of the nineties. The present paper lists genetic findings for TLE from the initial segregation analysis to the most recent results published in May 2011. To date, no genes have been clearly related to TLE despite many efforts to do so. However, it is vital to continue replication studies and collaborative attempts to find significant results and thus determine which gene variant combination plays a definitive role in the aetiology of TLE.

Lack of association between TNF-α gene polymorphisms at position -308 A, -850T and risk of simple febrile convulsion in pediatric patients

Background:

Febrile convulsions (FCs), occurring between 6 months and 6 years of age is the most common seizure disorder during childhood. The febrile response is thought to be mediated by the release of pyrogenic cytokines, such as tumor necrosis factor and interleukin-1 (IL-1). There is a significant relationship between genetic components for susceptibility of FCs and different report mutation. We investigated association between two polymorphisms in the tumor necrosis factor (TNF)-α promoter region (G-308A, C-850T) and FCs in the southwest area of Iran.

Materials and Methods:

In this matched case–control study, 100 patients with febrile convulsion as case group and 130 healthy children as control group were enrolled in the study. Peripheral blood samples were collected and DNA was extracted by standard phenol–chloroform method. The genotype and allele frequencies of TNF- α polymorphisms in case and control groups were determined by using PCR-RFLP (polymerase chain reaction restriction fragment length polymorphism) method. Statistical analysis was done using Chi-square test.

Results:

The average age of case and control groups were 3.4 ± 1.4 and 3.4 ± 1.2 years, respectively. There was no significant difference between age and sex in both the groups (P > 0.05). A family history of febrile convulsion was detected in 44% of patients. Moreover, the simple febrile convulsion was detected in 85% of the case group.

Conclusion:

RFLP analysis of TNF- α promoter region polymorphisms, considering P = 0.146 and P = 0.084 for G-308A and C-850T, respectively, showed no correlation between TNF- α polymorphisms and predisposition to simple febrile, based on the kind of convulsion (atypical and simple febrile convulsion). We found a significant relation between genotype distribution of G-308A and atypical febrile convulsion in case group (P = 0.04). A significant correlation between genotype distribution of G-308A and atypical febrile convulsion in the case group was found, but there was no correlation between TNF- α polymorphisms at positions of -308A, and 850T and predisposition to simple febrile convulsion. Further studies are needed to understand clinical usefulness of this correlation.

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.

Mutation screening of three Chinese families with genetic epilepsy with febrile seizures plus

Genetic epilepsy with febrile seizures plus (GEFS+) is a familial autosomal dominant condition characterized by genetic heterogeneity. Five genes for GEFS+ identified in large families account for only a small proportion of families. Mutation in the majority of families with GEFS+ has not identified yet. The aim of our study is to search for the gene responsible for GEFS+ in three Chinese families by linkage analyses and a sequencing approach and to investigate the importance of coding and noncoding regions variations of four known GEFS+ genes (SCN1A, SCN1B, GABRG2 and SCN2A) in Chinese families. Results showed that a 6-cM candidate interval at 5q33-34 with a maximum LOD scores of 2.043 was identified in families B. Sequencing candidate gene GABRG2 and GABRA1 in this region did not identify a causative mutation. Moreover, no mutation was found in coding and noncoding regions of the four genes in three Chinese families. Besides excluding coding regions of four known GEFS+ genes, we also excluded the possibility of a mutation in the promoter, exon-intron boundaries, 5' untranslated regions (5' UTRs), and 3' UTRs of four known GEFS+ genes in three Chinese families. In conclusion, the present study demonstrates the heterogeneity of the etiologies of GEFS+. There are as yet undiscovered mechanisms underlying GEFS+.

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.

The first genome-wide scan in a tunisian family with generalized epilepsy with febrile seizure plus (GEFS+)

Generalized epilepsy with febrile seizure plus (GEFS+) is an autosomal dominant disorder. In the literature, 5 responsible genes were identified and 2 novel susceptibility loci for GEFS+ at 2p24 and 8p23-p21 were reported, indicating the genetic heterogeneity of this disorder. The aim of this report is to identify the responsible loci in a large affected Tunisian family by performing a 10cM density genome-wide scan. The highest multipoint logarithm of odds (LOD) score (1.04) was found for D5S407 in the absence of recombination. Two other interesting regions were found around marker D19S210 (LOD=0.799) and D7S484 (LOD=0.61) markers. To fine map these loci, additional markers in 2 regions on 5q13.3 and 7p14.2 were analyzed and positive LOD scores for both loci were obtained. Sequencing of the Sodium channel subunit beta-1 gene (SCN1B) (19q13.1) showed the absence of any causal mutation. Our findings emphasized the genetic heterogeneity of febrile seizures.

Familial form of typical childhood absence epilepsy in a consanguineous context

Causative genes for childhood absence epilepsy (CAE) are unknown partly because families are small or phenotypically heterogeneous. In five consanguineous Tunisian families with at least two sibs with CAE, 14 patients fulfilled the diagnostic criteria for CAE (Epilepsia 1989; 30:389-399). Linkage analyses or direct sequencing excluded CACNG2, CACNA1A, CACNB4, and CACNA2D2, orthologs of genes responsible for autosomal recessive (AR) absence seizures in mice. These families will help identify (a) gene(s) responsible for CAE.

New mutation c.374C>T and a putative disease-associated haplotype within SCN1B gene in Tunisian families with febrile seizures

BACKGROUND

Febrile seizures (FSs) relatively represent the most common form of childhood seizures. FSs are not thought of as a true epileptic disease but rather as a special syndrome characterized by its provoking factor (fever) and a typical range of 3 months to 5 years. Although specific genes affecting the majority of FS cases have not been identified yet, several genetic loci for FSs have been reported recently. The aim of this report is to search for the gene responsible for FSs in six affected Tunisian families.

METHODS

A microsatellite marker analysis was performed on the known FS and generalized epilepsy with febrile seizures plus (GEFS+) loci. According to the results obtained by statistical analyses for the six studied families and in agreement with the involvement of SCN1B gene in the GEFS+ syndrome in previous studies, SCN1B on GEFS+1 locus was considered as one of the potential candidate genes and was tested for mutations by direct sequencing.

RESULTS

A sequencing analysis of the SCN1B gene revealed a novel mutation (c.374G>T) that changed an arginine residue with leucine at position 125 of the protein. We consider that the variation R125L may affect the protein structure and stability by the loss of hydrogen bonding. Two identified single nucleotide polymorphisms that are located in a neighboring hypothetical polyadenylation were assumed to compose a putative disease-associated haplotype.

CONCLUSION

Our results support that SCN1B is the gene responsible in one amongst the six FS Tunisian families studied and might contribute to the FS susceptibility for the five others.

Advances on the genetics of mendelian idiopathic epilepsies

Genetic factors play an increasingly recognized role in idiopathic epilepsies. Since 1995, positional cloning strategies in multi-generational families with autosomal dominant transmission have revealed 11 genes (KCNQ2, KCNQ3, CHRNA4, CHRNA2, CHRNB2, SCN1B, SCN1A, SCN2A, GABRG2, GABRA1, and LGI1) and numerous loci for febrile seizures and epilepsies. To date, all genes with the exception of LGI1 (leucine-rich glioma inactivated 1), encode neuronal ion channel or neurotransmitter receptor subunits. Molecular approaches have revealed great genetic heterogeneity, with the vast majority of genes remaining to be identified. One of the major challenges is now to understand phenotype-genotype correlations. This review focuses on the current knowledge on the molecular basis of these rare Mendelian autosomal dominant forms of idiopathic epilepsies.

Genetic susceptibility to febrile seizures: case-control association studies

OBJECTIVE

A genetic predisposition to febrile seizures (FS) has long been recognized. The inheritance appears to be polygenic in small families or sporadic cases of FS encountered in daily clinical practice. To determine whether candidate genes are responsible for the susceptibility to FS, we have performed genetic association studies in FS patients and controls.

METHODS

The single-nucleotide polymorphisms (SNPs) of genes involved in immune response (interleukin (IL) 1B), endocannabinoid signaling (CNR1), acid-base balance (SLC4A3, SLC9A1, SLC9A3), gap junction channel (CX43), and GABA(A) receptor trafficking (PRIP1) were examined in 249 FS patients (186 simple and 63 complex FS) and 225 controls.

RESULTS

There were no significant differences in the allele frequencies of the SNPs between controls and all FS, simple FS, and complex FS patients. When the simple FS patients were divided into two groups according to either having (familial) or not having a family history of FS in close relatives (sporadic), there was a significant association between IL1B -511 SNP and sporadic simple FS (p=0.003).

CONCLUSIONS

These data suggest that cytokine genes may act as enhancers or attenuators of FS susceptibility. Genetic association study may be an effective approach to understanding the molecular basis of FS at least in a subgroup of patients.

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.

Absence seizures: a review of recent reports with new concepts

Absence seizures with bilateral spike-wave (SW) complexes at 3Hz are divided into the childhood form, with onset at around 6 years of age, and the juvenile form, with onset usually at 12 years of age. These seizures typically last 9-12s and, at times, are activated by hyperventilation and occasionally by photic stimulation. Generalized tonic-clonic (GTC) seizures may also occur, especially in the juvenile form. There may be cognitive changes, in addition to linguistic and behavioral problems. Possible mechanisms for epileptogenesis may involve GABAergic systems, but especially T-calcium channels. The thalamus, especially the reticular nucleus, plays a major role, as does the frontal cortex, mainly the dorsolateral and orbital frontal areas, to the extent that some investigators have concluded that absence seizures are not truly generalized, but rather have selective cortical networks, mainly ventromesial frontal areas and the somatosensory cortex. The latter network is a departure from the more popular concept of a generalized epilepsy. Between the "centrencephalic" and "corticoreticular" theories, a "unified" theory is presented. Proposed genes include T-calcium channel gene CACNA1H, likely a susceptible gene in the Chinese Han population and a contributory gene in Caucasians. Electroencephalography has revealed an interictal increase in prefrontal activity, essential for the buildup of the ictal SW complexes maximal in that region. Infraslow activity can also be seen during ictal SW complexes. For treatment, counter to common belief, ethosuximide may not increase GTC seizures, as it reduces low-threshold T-calcium currents in thalamic neurons. Valproic acid and lamotrigine are also first-line medications. In addition, zonisamide and levetiracetam can be very helpful in absence epilepsy.

Progress in searching for the febrile seizure susceptibility genes

Febrile seizures (FS) represent the most common form of childhood seizures. They affect 2-5% of infants in the Caucasian population and are even more common in the Japanese population, affecting 6-9% of infants. Some familial FS are associated with a wide variety of afebrile seizures. Generalized epilepsy with febrile seizures plus (GEFS+) is a familial epilepsy syndrome with a spectrum of phenotypes including FS, atypical FS (FS+) and afebrile seizures. A significant genetic component exists for susceptibility to FS and GEFS+: extensive genetic studies have shown that at least nine loci are responsible for FS. Furthermore, mutations in the voltage-gated sodium channel subunit genes (SCN1A, SCN2A and SCN1B) and the GABA(A) receptor subunit genes (GABRG2 and GABRD) have been identified in GEFS+. However, the causative genes have not been identified in most patients with FS or GEFS+. Common forms of FS are genetically complex disorders believed to be influenced by variations in several susceptibility genes. Recently, several association studies on FS have been reported, but the results vary among different groups and no consistent or convincing FS susceptibility gene has emerged. Herein, we review the genetic data reported in FS, including the linkage analysis, association studies, and genetic abnormalities found in the FS-related disorders such as GEFS+ and severe myoclonic epilepsy in infancy.

Interleukin-10 is associated with resistance to febrile seizures: genetic association and experimental animal studies

PURPOSE

Febrile seizures (FS) are the most common form of childhood convulsions. Many reports have shown that a proinflammatory cytokine, interleukin-1 (IL-1) beta, may have a facilitatory effect on the development of FS. We have previously shown that the IL1B -511C/T single nucleotide polymorphism (SNP) is associated with simple FS of sporadic occurrence. The balance between pro- and antiinflammatory cytokines influences the regulation of infections and could, therefore, play a role in the pathogenesis of FS. Here, to determine whether pro- and antiinflammatory cytokine genes are responsible for the susceptibility to FS, we have performed an association study on functional SNPs of cytokine genes in FS patients and controls.

METHODS

The promoter SNPs of four inflammatory cytokine genes (IL6 -572C/G, IL8 -251A/T, IL10 -592A/C and TNFA -1037C/T) were examined in 249 patients with FS (186 simple and 63 complex FS) and 225 controls. Because the IL10 -592 SNP showed a positive association with FS, two additional SNPs (IL10 -1082A/G and -819T/C) were subjected to haplotype analysis. Furthermore, we examined the in vivo role of IL-10 in hyperthermia-induced seizures using immature animal models.

RESULTS

The frequencies of the IL10 -592C allele and -1082A/-819C/-592C haplotype were significantly decreased in FS as compared with in controls (p = 0.014 and 0.013, respectively). The seizure threshold temperature in the IL-10-administered rats was significantly higher than that in the saline-treated control ones (p = 0.027).

CONCLUSIONS

The present study suggests that IL-10 is genetically associated with FS and, contrary to IL-1beta, confers resistance to FS.

Incidence of febrile seizures in Finland: prospective population-based study

The objective was to study the incidence of febrile seizures prospectively determined through age 4 years. A standardized randomized cluster sample of nulliparous pregnant women from a geographically defined area were prospectively followed from the beginning of pregnancy through the child's age 4. Data on children eligible for the study (n = 1287), including febrile seizures, sociodemographic data, developmental milestones, and chronic diseases, were prospectively collected from families and health care staff. Data were available for 1033 children. Through age 4, the average annual incidence of febrile seizures was 14 per 1000 person-years (15 for girls and 13.5 for boys). The incidence rate through age 4 was 6.9% (7.3% for girls and 6.5% for boys). The incidence rate of febrile seizures in Finnish children is comparable to that reported previously. The higher figure, based on prospective rather than retrospective data, may give a more accurate picture of the clinical importance of febrile seizures.