RESUMO
Epilepsy is a complex neurological disorder characterized by sudden and recurrent seizures, which are caused by various factors, including genetic abnormalities. Several animal models of epilepsy mimic the different symptoms of this disorder. In particular, the genetic audiogenic seizure hamster from Salamanca (GASH/Sal) animals exhibit sound-induced seizures similar to the generalized tonic seizures observed in epileptic patients. However, the genetic alterations underlying the audiogenic seizure susceptibility of the GASH/Sal model remain unknown. In addition, gene variations in the GASH/Sal might have a close resemblance with those described in humans with epilepsy, which is a prerequisite for any new preclinical studies that target genetic abnormalities. Here, we performed whole exome sequencing (WES) in GASH/Sal animals and their corresponding controls to identify and characterize the mutational landscape of the GASH/Sal strain. After filtering the results, moderate- and high-impact variants were validated by Sanger sequencing, assessing the possible impact of the mutations by "in silico" reconstruction of the encoded proteins and analyzing their corresponding biological pathways. Lastly, we quantified gene expression levels by RT-qPCR. In the GASH/Sal model, WES showed the presence of 342 variations, in which 21 were classified as high-impact mutations. After a full bioinformatics analysis to highlight the high quality and reliable variants, the presence of 3 high-impact and 15 moderate-impact variants were identified. Gene expression analysis of the high-impact variants of Asb14 (ankyrin repeat and SOCS Box Containing 14), Msh3 (MutS Homolog 3) and Arhgef38 (Rho Guanine Nucleotide Exchange Factor 38) genes showed a higher expression in the GASH/Sal than in control hamsters. In silico analysis of the functional consequences indicated that those mutations in the three encoded proteins would have severe functional alterations. By functional analysis of the variants, we detected 44 significantly enriched pathways, including the glutamatergic synapse pathway. The data show three high-impact mutations with a major impact on the function of the proteins encoded by these genes, although no mutation in these three genes has been associated with some type of epilepsy until now. Furthermore, GASH/Sal animals also showed gene variants associated with different types of epilepsy that has been extensively documented, as well as mutations in other genes that encode proteins with functions related to neuronal excitability, which could be implied in the phenotype of the GASH/Sal. Our findings provide valuable genetic and biological pathway data associated to the genetic burden of the audiogenic seizure susceptibility and reinforce the need to validate the role of each key mutation in the phenotype of the GASH/Sal model.
Assuntos
Biologia Computacional , Epilepsia Reflexa/epidemiologia , Epilepsia/epidemiologia , Convulsões/epidemiologia , Estimulação Acústica , Animais , Cricetinae , Modelos Animais de Doenças , Epilepsia/tratamento farmacológico , Epilepsia/genética , Epilepsia/patologia , Epilepsia Reflexa/tratamento farmacológico , Epilepsia Reflexa/genética , Epilepsia Reflexa/patologia , Feminino , Regulação da Expressão Gênica/genética , Fatores de Troca do Nucleotídeo Guanina/genética , Humanos , Masculino , Proteína 3 Homóloga a MutS/genética , Mutação/genética , Convulsões/tratamento farmacológico , Convulsões/genética , Convulsões/patologia , Sequenciamento do ExomaRESUMO
PURPOSE: To describe the clinical and electroencephalographic (EEG) features of reflex myoclonic epilepsy in infancy (RMEI) and long-term cognitive outcome. METHODS: We enrolled 31 children from 16 neuropediatric centres in Italy, who underwent clinical and video-EEG evaluation. Cognitive assessment was performed in all patients using standardized psychometric tests. RESULTS: The age at onset ranged from 3 to 24 months of age. Seizures were characterised in all patients by symmetric myoclonic seizures (MS), triggered by sudden unexpected acoustic (38.7%) or tactile stimuli (29%) or both (29%). Spontaneous attacks were reported in 32.2% of the cases. Ictal EEG showed generalized high-amplitude 3 Hz polyspike and wave discharges, synchronous with brief rhythmic bursts of electromyographic activity. Patients were re-evaluated after a period of 7.2 ± 5.6 years. The prognosis for seizure control was excellent in all cases and reflex MS disappeared spontaneously or after valproate treatment. The cognitive outcome was excellent in 90.3% of children. CONCLUSIONS: RMEI appears to be a variety of idiopathic generalized epilepsy with specific features that occurs in developmentally normal children.