Apolipoprotein A5 genetic polymorphisms in Turkish population and the risk of ischemic stroke


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Biyolojik Bilimler Bölümü, Türkiye

Tezin Onay Tarihi: 2008

Öğrenci: ESRA ŞAHİN

Danışman: ORHAN ADALI

Özet:

Stroke is the third leading cause of death and the most common cause of disabilities worldwide. Apolipoprotein A5 gene (APO A5), which encodes a 369 amino acid protein called Apolipoprotein AV (apo AV), has several single nucleotide polymorphisms (SNPs) found to be associated with altered triglyceride (TG) levels. Atherosclerosis is a major cause of ischemic stroke and this pathology may be associated with variability of TG levels. The main objective of this study was to investigate the coding region (c.553G>T) and promoter region (-1131T/C) polymorphisms of the APO A5 gene as a risk factor for ischemic stroke. The study group in Turkish population consisted of 198 unrelated ischemic stroke patients and 130 control subjects. There was no statistically significant difference between the groups with respect to age and gender. Total blood samples were obtained from Gülhane Military Medical Academy Hospital, Neurology Department, Ankara. In stroke patients, hypertension and diabetes were 2.5 times more common and high-density lipoprotein cholesterol (HDL-C) was significantly lower than controls. Logistic regression analysis showed that hypertension, diabetes and smoking were significant predictors of stroke. The frequency of risky alleles c.553T and -1131C were 0.003 and 0.098, respectively, in patients and were nearly the same with controls. The risk of hypertensive and diabetic individuals having ischemic stroke was higher in -1131C allele carriers (Odds ratio; OR= 3.4 and 6.4, respectively) than -1131TT individuals (OR= 2.3 and 1.9, respectively). Stroke patients with -1131C allele had significantly higher TG levels (1.70 mmol/L) and lower HDL-C levels (1.05 mmol/L) when compared to controls (1.35 mmol/L and 1.20 mmol/L, respectively) with the same genotype. Logistic regression analysis revealed elevated TG level to be associated with 2.2-fold and low levels of HDL-C to be associated with 1.8-fold increase in the risk of ischemic stroke versus control status. This is the first study investigating the relation between APO A5 c.553G>T polymorphism and stroke risk. Additionally, in Turkish population -1131T/C polymorphism was analyzed for the first time in terms of its relation to ischemic stroke. The present study demonstrated that the frequency of risky alleles c.553T and-1131C were nearly the same in stroke patients and control subjects. Consequently, we decided that carrying minor alleles of c.553G>T and-1131T/C polymorphisms do not constitute a risk for ischemic stroke.