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Structure of GABA-A receptor A. Schematic structure of a subunit of a GABA-A receptor showing the large agonist-binding extracellular domain, the four transmembrane domains and the cytoplasmic loop between M3 and M4; B. Pentameric structure of a GABA-A receptor showing the transmembrane domains with the M2 domains facing the ion-conducting pore; C. Schematic structure of GABAA receptor showing the binding sites of chemical compounds that modulates GABA-A receptor action.
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The field of epilepsy genetics is contentious, particularly when it concerns the common epilepsies. More than a dozen loci have been suggested, the result of either linkage analysis and/or association analysis, but few of these findings have been replicated, let alone proven, and those that have are mostly for rare forms of epilepsy. Molecular gene...
Citations
... Most Mendelian disorders including many epilepsies are rare, making them unattractive for commercialisation and, in addition, the testing of some genes is protected by patents. 13 A low propensity to consider a genetic aetiology and delayed diagnoses also stifle advances in commercial genetic testing services and therapeutics. The reality for many public healthcare providers is that it is difficult to obtain funding for single gene testing despite established correlations between genotype and therapeutic protocols; for example, the ketogenic diet in patients diagnosed with GLUT1 deficiency. ...
Recent advances in molecular genetics have translated into the increasing utilisation of genetic testing in the routine clinical practice of neurologists. There has been a steady, incremental increase in understanding the genetic variation associated with epilepsies. Genetic testing in the epilepsies is not yet widely practiced, but the advent of new screening technologies promises to exponentially expand both knowledge and clinical utility. To maximise the value of this new genetic insight we need to rapidly extrapolate genetic findings to inform patients of their diagnosis, prognosis, recurrence risk and the clinical management options available for their specific genetic condition. Comprehensive, highly specific and sensitive genetic test results improve the management of patients by neurologists and clinical geneticists. Here we discuss the latest developments in clinical genetic testing for epilepsy and describe new molecular genetics platforms that will transform both genetic screening and novel gene discovery.
... Epilepsy is a chronic neurological illness, in which abnormal electrical activity in the brain causes involuntary changes in body movement, function, sensation, or behavior [1]. The World Health Organization estimates that epilepsy affects approximately 50 million people worldwide. ...
... The World Health Organization estimates that epilepsy affects approximately 50 million people worldwide. Now-a-days, we recognize that genetic factors play an even more important role in the pathogenesis of epilepsy and drug efficacy than previously appreciated [1,2]. Approximately, every second epileptic patient became resistant to the initial drugs [3]. ...
Some study found that ATP-binding cassette (ABC) efflux transporters play an important role in antiepileptic drug resistance, especially ABCB1 and ABCC2. The aims of this study were to evaluate the relationship between the genetic polymorphisms of ABCC2 and ABCB1 and the therapeutic efficacy of antiepileptic drugs (AEDs) in Chinese epileptic patients.
ABCB1 rs1045642 (3435C>T) and ABCC2 rs717620 (-24C>T), rs3740066 (3972C>T), and rs2273697 (1249G>A) polymorphisms loci in 537 Chinese epilepsy patients (217 drug resistant patients and 320 drug responders) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).
ABCC2 rs717620 -24TT genotype was significantly associated with drug resistant epilepsy (odds ratio [OR]= 4.06 [1.79-9.20], P= 0.001). The OR values of ABCC2 rs717620 -24 CT+TT genotypes and ABCC2 rs3740066 (3972C>T) CT+TT genotypes were markedly higher in drug resistant patients (OR = 1.57 [1.08-2.29], P= 0.018; OR = 1.49 [1.02-2.18], P= 0.038, respectively) compared with responsive patients. ABCC2 rs2273697 (1249G>A) and ABCB1 rs1045642 (3435C>T) polymorphisms were not associated with drug resistant epilepsy. Linkage disequilibrium (LD) test showed that the ABCC2 rs717620 were in strong LD with rs2273697 (D'= 0.694) and rs3740066 (D'= 0.699). The frequencies of haplotypes TGT (ABCC2 -24C>T/ABCC2 1249G>A/ABCC2 3972C>T) in resistant patients was significantly higher than those in responsive patients (21.0% vs. 14.2%, P < 0.05).
ABCC2-24C>T, 3972C>T polymorphisms and one ABCC2 haplotype is associated with AED resistance; ABCC2 1249G>A and ABCB1 3435C>T polymorphisms are not associated with AED resistance in our study. These data suggest that ABCC2 polymorphisms and haplotype may affect the response of antiepileptic drugs.
... Epilepsy is a chronic neurological illness, in which abnormal electrical activity in the brain causes involuntary changes in body movement, function, sensation, or behavior [1]. The World Health Organization estimates that epilepsy affects approximately 50 million people worldwide. ...
... The World Health Organization estimates that epilepsy affects approximately 50 million people worldwide. Now-a-days, we recognize that genetic factors play an even more important role in the pathogenesis of epilepsy and drug efficacy than previously appreciated [1,2]. Approximately, every second epileptic patient became resistant to the initial drugs [3]. ...
The first three authors contributed equally to this work. SUMMARY Aims: Some study found that ATP-binding cassette (ABC) efflux transporters play an im-portant role in antiepileptic drug resistance, especially ABCB1 and ABCC2. The aims of this study were to evaluate the relationship between the genetic polymorphisms of ABCC2 and ABCB1 and the therapeutic efficacy of antiepileptic drugs (AEDs) in Chinese epileptic pa-tients. Methods: ABCB1 rs1045642 (3435C>T) and ABCC2 rs717620 (−24C>T), rs3740066 (3972C>T), and rs2273697 (1249G>A) polymorphisms loci in 537 Chinese epilepsy pa-tients (217 drug resistant patients and 320 drug responders) were genotyped by poly-merase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: ABCC2 rs717620 −24TT genotype was significantly associated with drug resistant epilepsy (odds ratio [OR] = 4.06 [1.79–9.20], P = 0.001). The OR values of ABCC2 rs717620 −24 CT+TT genotypes and ABCC2 rs3740066 (3972C>T) CT+TT genotypes were markedly higher in drug resistant patients (OR = 1.57 [1.08–2.29], P = 0.018; OR = 1.49 [1.02–2.18], P = 0.038, respectively) compared with responsive patients. ABCC2 rs2273697 (1249G>A) and ABCB1 rs1045642 (3435C>T) polymorphisms were not associated with drug resistant epilepsy. Linkage disequilibrium (LD) test showed that the ABCC2 rs717620 were in strong LD with rs2273697 (D' = 0.694) and rs3740066 (D' = 0.699). The frequencies of haplotypes TGT (ABCC2 −24C>T/ABCC2 1249G>A/ABCC2 3972C>T) in resistant patients was signifi-cantly higher than those in responsive patients (21.0% vs. 14.2%, P < 0.05). Conclusion: ABCC2 −24C>T, 3972C>T polymorphisms and one ABCC2 haplotype is associated with AED resistance; ABCC2 1249G>A and ABCB1 3435C>T polymorphisms are not associated with AED resistance in our study. These data suggest that ABCC2 polymorphisms and haplotype may affect the response of antiepileptic drugs.
ATP1A2 and ATP1A3 are genes that code for catalytic subunits of Na/K-ATPases, which play important roles in the basal electrophysiological states of nerve cells. The aim of this study was to investigate whether genetic polymorphisms of ATP1A2 and ATP1A3 influence susceptibility to genetic generalized epilepsies (GGEs) and the efficacy of anti-epileptic drugs in a Chinese population.
Six ATP1A2 tagged single-nucleotide polymorphisms (tagSNPs) and two ATP1A3 tagSNPs were were genotyped by allele-specific MALDI-TOF mass spectrometry in 484 Chinese GGE patients (280 drug-responsive and 204 drug-resistant patients) and 284 healthy controls.
Significant differences were found in the frequencies of the ATP1A3 rs8107107 C allele and the CC genotype between the GGEs and the healthy controls (11% vs. 15%, odds ratio (OR)=0.807 (0.68-0.960), p=0.021 and 0.4% vs. 3.2%, OR=0.121 (0.026-0.565), p=0.002, respectively). The frequency of the rs8107107 CT+CC genotype was significantly lower among the GGE patients than among the healthy controls (15% vs. 26.8%, OR=0.327 (0.248-0.942), p=0.001). No significant differences in the frequencies of six ATP1A2 tagSNPs or ATP1A2 haplotypes were found between the GGEs and the healthy controls. No tagSNPs were involved in anti-epileptic drug resistance.
Our findings demonstrated that common variants of ATP1A3 but not ATP1A2 were associated with the susceptibility to GGEs in a Chinese population, which indicates that the ATP1A3 gene plays a significant role in the pathophysiology of genetic generalized epilepsies.
Copyright © 2015 Elsevier B.V. All rights reserved.
