Lack of Evidence for Contribution of Endothelial Nitric Oxide Synthase Intron 4 VNTR Gene Polymorphisms to Development of Ischemic Stroke in Turkish Subjects

The gene polymorphisms of the vasodilator endothelial nitric oxide synthase (eNOS) are considered as important candidate genetic risk factors for vascular diseases. The present study aimed to assess the genotypic distribution and the allelic frequency of the four repeats (a allele), and the five repeats (b allele) of 27 bp in intron 4 of eNOS gene (eNOS VNTR 4 a/b) in Turkish ischemic stroke patients compared to controls. The study population included 197 (102 males, 95 females) patients with ischemic stroke which were categorized according to the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) as large vessel disease or small vessel disease patients, and 144 (36 males, 108 females) controls. The eNOS VNTR 4 a/b gene polymorphisms were identified with a polymerase chain reaction. Genotypes were defined as aa; 394 bp fragment, ab; 394 and 421 bp fragments, and bb; 421 bp fragment according to the presence of the a and b alleles. In this stroke-control study, we did not find any significant difference in either the genotypic distribution or allelic frequency of eNOS VNTR 4 a/b gene polymorphism between the ischemic stroke patients and the controls (p>0.05). We also did not find any significant difference in either the genotypic distribution or allelic frequency according to gender (p>0.05). In addition, there was also no significant difference for the genotype distribution and the allelic frequency among the stroke subtypes (p>0.05), or according to gender in stroke subgroups (p>0.05). The results suggested the lack of an association between the VNTR 4 a/b gene polymorphisms of eNOS gene and ischemic stroke or between the VNTR 4 a/b gene polymorphisms of eNOS gene and subtypes of ischemic stroke in Turkish population in the Trakya region.