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Gama amino butirik asit (GABA) reseptörlerinin genetik polimorfizmleri ile idiyopatik jeneralize epilepsi arasındaki ilişkinin araştırılması

Bek, Semai Vedat
Adalı, Orhan
Eroğlu, Ezgi
Miçooğulları, Yağmur
Demirdöğen, Can Birsen
Epilepsy is one of the most common neurological diseases worldwide. Gamma amino butyric acid (GABA), the most important inhibitory neurotransmitter of the central nervous system, and its receptors are commonly mentioned in the pathophysiology of epilepsies. Some of the single nucleotide polymorphisms in the genes encoding GABA receptors have been reported to increase susceptibility to temporal lobe epilepsy. There are a limited number of studies analyzing the relationship of GABA receptors and idiopathic epilepsy, which is the most widespread (65%) when etiologically classified. In Turkish population, genetic polymorphisms of GABAA, GABAB1 and GABAB2 receptors have not been studied before. For these reasons, in this study we aimed to determine the frequencies of genetic polymorphisms of GABA receptors A, B1 and B2 in Turkish population by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) method, and to investigate the correlation between these polymorphisms and idiopathic generalized epilepsy (IGE). A second aim of this study was to analzye the role of GABA receptor polymorphisms in differential diagnosis of pschogenic non-epileptic seizure (PNES). In this context, 196 IGE patients, 107 PNES subjects and 109 controls were inculded in this study. Polymorphic allele frequencies were very close to each other in the three groups (0.457 in IGE patients, 0.453 in PNES patients and 0.427 in controls) for the GABAA α1 rs2279020 polymorphism. A statistically significant relationship was not found between this polymorphism and IGE. We did not observe polymorphic alleles in Turkish population for GABAA 2 rs17852044, GABAA 3 rs79829085 and GABAB1 G1465A. For GABAB1 C59T polymorphism, when IGE patients and PNES subjects were compared, C59T polymorphism was found to increase IGE risk 1,5 times, but this result was not significant (P=0.164). The frequency of C59T polymorphism in control population was found as 0.110 in this study. We observed that four polymorphisms found on GABAB2 gene (rs3780428-rs1999501- rs967932-rs94688) did not constitute a significant risk for IGE when considered alone. When the genotype combinations were taken into account, we concluded that having polymorphic homozygote genotype for rs944688 and wild type genotype for rs967932 and rs1999501 had 15 times protective effect against IGE for PNES subjects (P=0.001). The same genotype combination constituted 12 times protective effect against IGE in control subjects (P=0.009). This triple combined genotype can be used to differentiate subjects who have psychogenic seizures (PNES) from those having epileptic seizures. All of the studied polymoprhisms were studied for the first time in Turkish population