Targeted sequencing of 351 candidate genes for epileptic encephalopathy in a large cohort of patients

Peer reviewe

Targeted sequencing of 351 candidate genes for epileptic encephalopathy in a large cohort of patients

Many genes are candidates for involvement in epileptic encephalopathy (EE) because one or a few possibly pathogenic variants have been found in patients, but insufficient genetic or functional evidence exists for a definite annotation

Genomewide linkage in a large Dutch family with intracranial aneurysms - Replication of 2 loci for intracranial aneurysms to chromosome 1p36.11-p36.13 and Xp22.2-p22.32

Background and Purpose - Approximately 2% of the general population harbor intracranial aneurysms. The prognosis after rupture of an intracranial aneurysm is poor; 50% of the patients die as a result of the rupture. Familial occurrence of intracranial aneurysms suggests there are genetic factors involved in the development of such aneurysms.Methods - A large, consanguineous pedigree with 7 of 20 siblings affected by intracranial aneurysms was compiled and a genomewide linkage analysis on this family was performed using Illumina's single nucleotide polymorphism-based linkage panel IV, which includes 5861 single nucleotide polymorphisms. A nonparametric linkage affecteds-only approach with GENEHUNTER was used.Results - Two loci with suggestive linkage (nonparametric linkage = 3.18) on chromosome regions 1p36 and Xp22 were identified. Additional microsatellite markers were genotyped in the 2 candidate loci and showed suggestive linkage to the locus on chromosome 1 with a nonparametric linkage of 3.18 at 1p36.11-p36.13 and significant linkage to the locus on chromosome X with a nonparametric linkage of 4.54 at Xp22.2-p22.32.Conclusions - The 2 potential loci for intracranial aneurysms, which we identified in this large Dutch family, overlap with loci that have already been identified in previous linkage studies from different populations. Identification of genes from these loci will be important for a better understanding of the disease pathogenesis.</p

GENETIC SUSCEPTIBILITY TO RESPIRATORY SYNCYTIAL VIRUS BRONCHIOLITIS IN PRETERM CHILDREN IS ASSOCIATED WITH AIRWAY REMODELING GENES AND INNATE IMMUNE GENES

Prematurity is a risk factor for severe respiratory syncytial virus bronchiolitis. We show that genetic factors in innate immune genes (IFNA13, IFNAR2, STAT2. IL27, NFKBIA, C3, IL1RN, TLR5), in innate and adaptive immunity (IFNG), and in airway remodeling genes (ADAM33 and TGFBR1), affect disease susceptibility to a different extent in preterm children, born with underdeveloped lungs, than in term children

NaV1.1 and NaV1.6 selective compounds reduce the behavior phenotype and epileptiform activity in a novel zebrafish model for Dravet syndrome

Dravet syndrome is caused by dominant loss-of-function mutations in SCN1A which cause reduced activity of Nav1.1 leading to lack of neuronal inhibition. On the other hand, gain-offunction mutations in SCN8A can lead to a severe epileptic encephalopathy subtype by over activating NaV1.6 channels. These observations suggest that Nav1.1 and Nav1.6 represent two opposing sides of the neuronal balance between inhibition and activation. Here, we hypothesize that Dravet syndrome may be treated by either enhancing Nav1.1 or reducing Nav1.6 activity. To test this hypothesis we generated and characterized a novel DS zebrafish model and tested new compounds that selectively activate or inhibit the human NaV1.1 or NaV1.6 channel respectively. We used CRISPR/Cas9 to generate two separate Scn1Lab knockout lines as an alternative to previous zebrafish models generated by random mutagenesis or morpholino oligomers. Using an optimized locomotor assay, spontaneous burst movements were detected that were unique to Scn1Lab knockouts and disappear when introducing human SCN1A mRNA. Besides the behavioral phenotype, Scn1Lab knockouts show sudden, electrical discharges in the brain that indicate epileptic seizures in zebrafish. Scn1Lab knockouts showed increased sensitivity to the GABA antagonist pentylenetetrazole and a reduction in whole organism GABA levels. Drug screenings further validated a Dravet syndrome phenotype. We tested the NaV1.1 activator AA43279 and two novel NaV1.6 inhibitors MV1369 and MV1312 in the Scn1Lab knockouts. Both type of compounds significantly reduced the number of spontaneous burst movements and seizure activity. Our results show that selective inhibition of NaV1.6 could be just as efficient as selective activation of NaV1.1 and these approaches could prove to be novel potential treatment strategies for Dravet syndrome and other (genetic) epilepsies. Compounds tested in zebrafish however, should always be further validated in other model systems for efficacy in mammals and to screen for potential side effects

Genetic susceptibility to respiratory syncytial virus bronchiolitis is predominantly associated with innate immune genes

Background. Respiratory syncytial virus (RSV) is a common cause of severe lower respiratory tract infection in infants. Only a proportion of children infected with RSV require hospitalization. Because known risk factors for severe disease, such as premature birth, cannot fully explain differences in disease severity, genetic factors have been implicated. Methods. To study the complexity of RSV susceptibility and to identify the genes and biological pathways involved in its development, we performed a genetic association study involving 470 children hospitalized for RSV bronchiolitis, their parents, and 1008 random, population controls. We analyzed 384 single - nucleotide polymorphisms (SNPs) in 220 candidate genes involved in airway mucosal responses, innate immunity chemotaxis, adaptive immunity, and allergic asthma. Results. SNPs in the innate immune genes VDR (rs10735810; P = .0017), JUN (rs11688; P = .0093), IFNA5 (rs10757212; P = .0093), and NOS2 (rs1060826; P = .0031) demonstrated the strongest association with bronchiolitis. Apart from association at the allele level, these 4 SNPs also demonstrated association at the genotype level (P = .0056, P = .0285, P = .0372, and P = .0117 for the SNPs in VDR, JUN, IFNA5, and NOS2, respectively). The role of innate immunity as a process was reinforced by association of the whole group of innate immune SNPs when the global test for groups of genes was applied (P = .046) Conclusion. SNPs in innate immune genes are important in determining susceptibility to RSV bronchiolitis

Recessive mutations in SLC13A5 result in a loss of citrate transport and cause neonatal epilepsy, developmental delay and teeth hypoplasia

The epileptic encephalopathies are a clinically and aetiologically heterogeneous subgroup of epilepsy syndromes. Most epileptic encephalopathies have a genetic cause and patients are often found to carry a heterozygous de novo mutation in one of the genes associated with the disease entity. Occasionally recessive mutations are identified: a recent publication described a distinct neonatal epileptic encephalopathy (MIM 615905) caused by autosomal recessive mutations in the SLC13A5 gene. Here, we report eight additional patients belonging to four different families with autosomal recessive mutations in SLC13A5. SLC13A5 encodes a high affinity sodium-dependent citrate transporter, which is expressed in the brain. Neurons are considered incapable of de novo synthesis of tricarboxylic acid cycle intermediates; therefore they rely on the uptake of intermediates, such as citrate, to maintain their energy status and neurotransmitter production. The effect of all seven identified mutations (two premature stops and five amino acid substitutions) was studied in vitro, using immunocytochemistry, selective western blot and mass spectrometry. We hereby demonstrate that cells expressing mutant sodium-dependent citrate transporter have a complete loss of citrate uptake due to various cellular loss-of-function mechanisms. In addition, we provide independent proof of the involvement of autosomal recessive SLC13A5 mutations in the development of neonatal epileptic encephalopathies, and highlight teeth hypoplasia as a possible indicator for SLC13A5 screening. All three patients who tried the ketogenic diet responded well to this treatment, and future studies will allow us to ascertain whether this is a recurrent feature in this severe disorder

Clinical and genetic analysis of a family with two rare reflex epilepsies

Purpose: To determine clinical phenotypes, evolution and genetic background of a large family with a combination of two unusual forms of reflex epilepsies. Method: Phenotyping was performed in eighteen family members (10 F, 8 M) including standardized EEG recordings with intermittent photic stimulation (IPS). Genetic analyses (linkage scans, Whole Exome Sequencing (WES) and Functional studies) were performed using photoparoxysmal EEG responses (PPRs) as affection status. Results: The proband suffered from speaking induced jaw-jerks and increasing limb jerks evoked by flickering sunlight since about 50 years of age. Three of her family members had the same phenotype. Generalized PPRs were found in seven members (six above 50 years of age) with myoclonus during the PPR. Evolution was typical: Sensitivity to lights with migraine-like complaints around adolescence, followed by jerks evoked by lights and spontaneously with dropping of objects, and strong increase of light sensitivity and onset of talking induced jaw jerks around 50 years. Linkage analysis showed suggestive evidence for linkage to four genomic regions. All photosensitive family members shared a heterozygous R129C mutation in the SCNM1 gene that regulates splicing of voltage gated ion channels. Mutation screening of 134 unrelated PPR patients and 95 healthy controls, did not replicate these findings. Conclusion: This family presents a combination of two rare reflex epilepsies. Genetic analysis favors four genomic regions and points to a shared SCNM1 mutation that was not replicated in a general cohort of photosensitive subjects. Further genetic studies in families with similar combination of features are warranted. (C) 2015 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved

Multiple independent variants in 6q21-22 associated with susceptibility to celiac disease in the Dutch, Finnish and Hungarian populations

Celiac disease is an inflammatory enteropathy caused by intolerance to gluten. Previous linkage studies in the Dutch, Finnish and Hungarian populations have revealed a locus on chromosome 6q21-22 conferring susceptibility to celiac disease. This locus has previously been implicated in susceptibility to other autoimmune diseases such as Crohn's disease and type 1 diabetes. We performed fine mapping on 446 independent individuals with celiac disease and 641 controls of Dutch origin, testing 872 tagging SNPs in a 22 Mb region of chromosome 6. The 12 most promising SNPs were followed up in 2071 individuals from 284 Finnish and 357 Hungarian celiac disease families to identify risk variants in this region. Multiple markers in the region were significantly associated with celiac disease in the Dutch material. Two SNPs, rs9391227 and rs4946111, were significantly associated with celiac disease in the Finnish population. The association to rs9391227 represents the strongest association signal found in the Finnish (P=0.003, OR 0.66) as well as the combined Dutch, Finnish and Hungarian populations (P=3.6 × 10−5, OR 0.76). The rs9391227 is situated downstream of the HECT domain and ankyrin repeat containing, E3 ubiquitin protein ligase 1 (HACE1) gene and is contained within a region of strong linkage disequilibrium enclosing HACE1. Two additional, independent, susceptibility variants in the 6q21-22 region were also found in a meta-analysis of the three populations. The 6q21-22 region was confirmed as a celiac disease susceptibility locus and harbors multiple independent associations, some of which may implicate ubiquitin-pathways in celiac disease susceptibility

Sledování změny jakosti masného výrobku v závislosti na technologii výroby

Vysočina salami is the best known and the most widespread product of durable heat-treated meat products in the Czech Republic. Chemical, physical, microbiological and sensory parameters were examined for this product depending on salt content (2 % or 1,6 %) and grain size (1 mm, or 2 mm). There was found no difference that would be important from a technological point of view during comparing the fine and coarser grain in the Vysočina salami. By comparing differently salty products, lower salt content could cause manufacturing problems. By reducing the salt content, the drying time was prolonged, and the colour stability deteriorated. It is advisable to reduce the salt content to the lowest possible level in order to improve the health aspect of the consumption of meat products but at the same time the technological characteristics of the production are not affected. Finally, salt is important for the taste of the product. This was clearly demonstrated in sensory analysis. The analysis shows the Vysočina salami with 2 % salt addition has been more palatable to the consumer