Date

2011

Author

Miçooğulları, Yağmur

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Stroke is characterized with loss of one or more functions of the body resulted by inadequate blood supply to the brain. Most of the cases result from a blood clot forms on an atherosclerotic plaque in the brain which is called as ischemic stroke. Structure of the arteries and vascular tone are listed in major determinants in the development of the disorder. Soluble epoxide hydrolase (sEH, EPHX2) catalyzes conversion of epoxyeicosatrienoic acids to inactive diol metabolites. EETs are potent vasodilators that participate in the regulation of vascular tone and cerebral blood flow. Microsomal epoxide hydrolase (mEH, EPHX1) is a critical phase I enzyme that catalyzes the conversion of various xenobiotic epoxide substrates and polycyclic aromatic hydrocarbons (PAHs). Animal studies show that tobacco smoke mutagens such as PAHs and heterocyclic amines directly increase the development of atherosclerotic lesions. The main purpose of this study is evaluation of effect of Arg287Gln single nucleotide polymorphism of EPHX2 gene and Tyr113His and His139Arg single nucleotide polymorphisms of EPHX1 gene as a risk factor for ischemic stroke in Turkish population. Blood samples of 237 ischemic stroke patients and 120 controls were collected and all polymorphisms were determined by PCR-RFLP method. Mutant allele frequencies in terms of Arg287Gln polymorphism of EPHX2 gene (A) were found as 0.08 for patient group and 0.09 for controls. Tyr113His polymorphism of EPHX1 gene (C) were found as 0.27 for patient group and 0.31 for controls when, His139Arg polymorphism of EPHX1 gene (G) were 0.820 and 0.814 for patient and control groups, respectively. The differences between mutant allele frequencies of patients and controls were not found to be statistically significant. Subgroup analysis was used to investigate the effects of conventional vascular factors according to the genotypes in the stroke susceptibility. Smoking, diabetes, obesity and hypertension were found to significantly increase the risk of having stroke. More detailed analysis on these factors with respect to genotypes showed that the risk of hypertensive individuals having ischemic stroke was higher in wild type homozygous genotype groups of Tyr113His (TT) and His139Arg (AA) polymorphisms and heterozygous and mutant homozygous genotypes of Arg287Gln (GA+AA) polymorphism than their counterparts (OR= 3.21, 3.15 and 4.69, respectively). Smoker people within the heterozygous and mutant homozygous genotypes group of Arg287His (GA+AA) polymorphism and wild type homozygous group of His139Arg (AA) polymorphism were found to be more susceptible to have stroke (OR= 11.81 and 4.78 respectively). Finally, diabetes mellitus was found to double the risk of having stroke regardless of the genetic background. Logistic regression analyses were used to ascertain the effects of vascular factors, lipid parameters and genotypes in the stroke susceptibility. LDL-cholesterol (OR=1.46; 95%CI, 1.12-1.89, P=0.00), smoking (OR=3.46; 95%CI, 1.66-7.21, P=0.00) and hypertension (OR=3.19; 95%CI, 1.92-5.30, P=0.00) were found to be significant risk factors for ischemic stroke, whereas HDL (OR=0.27; 95%CI, 0.12-0.65, P=0.02) was found to be a protective factor in general population. In this study, the relation of Tyr113His and His139Arg polymorphisms of EPHX1 gene and risk of ischemic stroke is investigated for the first time in literature while, Arg287Gln polymorphism and ischemic stroke risk in Turkish population was studied for the first time.

Subject Keywords

Transient ischemic attack.

URI

http://etd.lib.metu.edu.tr/upload/12613497/index.pdf
https://hdl.handle.net/11511/20721

Collections

Graduate School of Natural and Applied Sciences, Thesis