eNOS Gene Intron 4 VNTR and Exon 7-G894T Polymorphisms in Turkish Men with Erectile Dysfunction: A Case Control Study

Abstract

Introduction The associations between the gene polymorphisms and erectile dysfunction (ED) are limited. Aim To examine a potential association between variable number of tandem repeats (intron 4 VNTR), G894T polymorphisms, and ED in Turkish men. Methods Sixty-four men with ED and 82 healthy men as a control group were included in the study. The patients were evaluated by medical history, International Index of Erectile Function (IIEF), serum glucose, and lipid profiles. VNTR and G894T polymorphism were assessed by isolated DNA blood samples obtained from the patient group with ED and controls. Main Outcome Measures Assesment of IIEF and VNTR and G894T polymorphism in the isolated DNA blood samples. Results Genotype distributions of endothelial nitric oxide syntase (eNOS) gene intron 4 VNTR polymorphisms in the patient group were similar to those in the healthy group (P > 0.05). The frequency of the eNOS gene intron 4 genotype was found as bb: 55 (67.1%), ab: 26 (31.7%), and aa: 1 (1.2%) in the controls and bb: 43 (67.2%), ab: 19 (29.7%), and aa: 2 (3.1%) in the patient group. The frequency of the G894T was found as gg: 61 (74.4%), gt: 21 (25.6%), and tt: 0 (0.0%) in the controls and gg: 32 (50.0%), gt: 27 (42.1%), and tt: 5 (7.8%) in the patient group (P = 0.002). The frequencies of the “t” allele were 21 (12.8%) in the control group and 37 (28.9%) in the patient group (P = 0.001). Logistic regression analysis showed that G894T polymorphism was an independent risk factor for ED. Conclusions We found significant differences in allelic and genotypic frequencies between patients and controls for the G894T eNOS polymorphisms. The presence of 894T allele in carriers increased the risk of ED. No association was found between VNTR polymorphism and in patients with ED.

Endothelial Nitric Oxide Synthase Polymorphisms and Erectile Dysfunction: A Meta-Analysis

“…Although functional experiments support the involvement of eNOS in the pathogenesis of ED [18], results of association studies regarding the relationship between eNOS variants and ED risk have remained inconsistent. More specifically, it has been reported that 894T allele carriers were associated with an increased risk of ED in Mexican and Turkish populations [19,20]. Another study conducted in Germany, however, showed no significant relationship between G894T polymorphism and ED [21].…”

Association of endothelial nitric oxide synthase polymorphisms with an increased risk of erectile dysfunction

“…Besides, 2 low-quality studies were also excluded ( Figure 1 ). Finally, 12 studies were enrolled into our meta-analysis 22526373839404142434445. The subjects in these 12 studies were Asians (5 studies) and Caucasians (7 studies), and the studies contained a combined total of 1962 ED patients and 1752 healthy controls.…”

“…Measurement of eNOS enzyme activity in T allele carriers revealed 20% lower activity compared to individuals homozygous for the G allele 26. Erectile function depends on the relaxation and contraction of penis which is regulated by smooth muscle, and G894T polymorphism was found to interfere with this process, increasing ED predisposition 41. The two SNPs (T-786C and G894T) variously affect either eNOS transcription rate or its enzyme activity to dramatically reduce NO production, resulting in decreased functioning of the eNOS/NO system to buffer blood pressure fluctuations 21.…”

Genetics of Erectile Dysfunction: A Review of the Interface between Sex and Molecular Biomarkers

“…Polymorphisms in eNOS gene have been hypothesized to be associated with erectile complaints. A polymorphism located in exon 7 of the eNOS gene (G894T) has been the focus of a number of studies regarding the influence of eNOS on ED susceptibility [24,30–32]. The T allele, which results in a substitution of aspartate for glutamate at amino acid position 298 of eNOS, has been associated with a significantly higher risk of ED in Mexican, Taiwanese, Turkish, and Iranian populations [24,30–33].…”