Epilepsy affects over 450,000 people in the UK and there are over 50 epilepsy phenotypes; genetic generalised epilepsy (GGE) account for up to 30% of seizure types. It is established that GGE and other neurological disorders are, in some cases, caused by channelopathies within post-synaptic inhibitory neurotransmitter systems such as GAB A (epilepsy) and Glycine (hyperekplexia). GAB A is the primary inhibitory neurotransmitter in the brain and is synthesised from glutamate by GAD65 and 67, and is released from the pre-synaptic nerve terminal into the synaptic cleft, where it binds to post-synaptic GABA receptors and initiate neuroinhibition. This inhibition is removed by post-synaptic GABA transporters (GAT1 and GAT3) that uptake GABA back into the cell for re-packaging in presynaptic vesicles or breakdown by transamination. Abnormalities in this system have been linked to diseases including anxiety, psychosis, Parkinsons’s Disease and epilepsy. GABAergic animal models have demonstrated a tendency to seizure, including GABA transporter and enzyme models in relation to epilepsy. Given the above, the aim of this study was to identify GGE causing variants in four GABAergic genes. GGE patient samples (n=101) were recruited from 3 global centres and screened for variations in GAT1, GAT3, GAD65, GAD67 using high-throughput LightScanner analysis and bi-directional Sanger sequencing. Control population studies («=480) were carried out and analysis of online databases to determine the frequency of variants. Twenty novel or very rare variants were identified in 48 patient samples representing a detection rate of 6.8%, where a clustering of phenotypes included a predisposition towards absence seizures. The biological consequences of these variants were predicted using three online predictive programmes, multiple phylogenetic alignments and 3D structural modelling. Mutation expression constructs were prepared and expression levels were validated by immunocytochemistry. Functional characterisation of these variants will hopefully improve genetic diagnosis in GGE and determine causality of GABAergic absence seizures.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:678392 |
| Date | January 2015 |
| Creators | Hunt-Jones, Charlotte Amy |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://cronfa.swan.ac.uk/Record/cronfa43036 |
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