Glu298Asp Endothelial Nitric Oxide Synthase Polymorphism Is a Risk Factor for Erectile Dysfunction in the Mexican Mestizo Population

Genetics and erectile dysfunction: leveraging early foundations for new discoveries

There is considerable interest in understanding the genetics of erectile dysfunction (ED). Since early twin studies that suggested a genetic component to ED, multiple candidate gene studies have identified genetic variants that may be associated with ED. Genome-wide association studies (GWAS) have overcome some of the criticism of the candidate gene approach. Two recent GWAS studies have identified loci near SIM1 that may be associated with ED and have renewed interest in the leptin melanocortin signaling pathway. We review the current literature on the genetic basis of ED by highlighting several candidate genes and genetic variants associated with ED.

The association of Intron 4 VNTR and Glu298Asp polymorphisms of the nitric oxide synthetase 3 gene and vasculogenic erectile dysfunction in Turkish men

Several studies have focused on the impaired role of endothelial nitric oxide synthase (NOS3) gene polymorphism and its association to erectile dysfunction (ED). However, currently controversial results have been reported due to their significant heterogeneity. The present study aimed to assess the genotypic distribution and the allelic frequency of Intron 4 VNTR and Glu298Asp gene polymorphisms in vasculogenic ED patients compared to healthy controls of a specific region of Turkey. A total of 75 patients with ED (median age: 56, IQR:10.5) and 75 healthy controls (median age: 56, IQR:10.5) were prospectively analyzed. All subjects were equally evaluated by the same physician with detailed history-taking, physical examination, International Index of Erectile Function (IIEF) questionnaire, and blood tests (incl. glucose, testosterone, triglyceride and total cholesterol level). Those with an IIEF score under 26 were considered to have ED, by classifying them according to their scores as mild (22-25), moderate (11-21) and severe (1-10) ED. Color doppler ultrasonography was carried out in patients with an IIEF score <22. Hypertension, diabetes mellitus, coronary artery disease, and smoking status were significantly associated with the ED group compared to control subjects with p values of <0.001, <0.001, 0.002 and <0.001, respectively. Overall genotype frequencies was 47 (31%) a/a, 22 (15%) a/b, 82 (55%) b/b for Intron 4 VNTR and 56 (37%) GG, 78 (52%) GT, 16 (11%) TT for the Glu298Asp polymorphism. The frequencies of Intron 4 VNTR a/a allele and Glu298Asp GT allele were associated with severe ED, while a/b and TT were associated with moderate or mild, and b/b and GG were associated with no ED. In contrast to Glu298Asp, statistically significant differences in genotypic frequencies of Intron 4 VNTR gene polymorphism between ED and control subjects was established. Abbreviations: NO: nitric oxide, NOS: nitric oxide synthase, NOS3: endothelial nitric oxide synthase, NOS2: inducible nitric oxide synthase, NOS1: neuronal nitric oxide synthase, HT: hypertension, DM: diabetes mellitus, CAD: coronary artery disease, ED: erectile dysfunction, IIEF: international index of erectile function, VNTR: variable number of tandem repeats, CDU: color doppler ultrasonography, PCR: polymerase chain reaction.

Back to Stir It Up: Erectile Dysfunction in an Evolutionary, Developmental, and Clinical Perspective

In this review, we analyze erectile dysfunction (ED) in the context of sexual selection. We highlight that ED is a specific human male characteristic linked to the loss of the baculum or penile bone and results from a range of physical and psychological factors. We discuss evolutionary interpretations that consider dysfunctional penile erection as an honest signal of a low-quality male. We further emphasize the importance of considering psychosocial context and early attachment dynamics for understanding the etiology of some types of ED. Finally, we suggest that the integration of developmental factors for understanding the emergence of this sexual disorder is instrumental for the calibration of more effective therapies.

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

The purpose of our meta-analysis is to examine the associations between three single nucleotide polymorphisms of endothelial nitric oxide synthase (eNOS) gene, G894T, intron 4 and T-786C, and the risk of erectile dysfunction. An electronic database search was performed to identify case-control studies reporting the association between single nucleotide polymorphisms of eNOS gene and erectile dysfunction. Stringent inclusion and exclusion criteria were employed to select high-quality studies for this meta-analysis. Comprehensive Meta-analysis 2.0 software (Biostat Inc., Englewood, New Jersey, USA) was used for statistical analysis of the data extracted from the selected studies. From the initial 203 articles retrieved from database search, this meta-analysis finally selected 12 high-quality case-control studies that conformed to our inclusion criteria. The 12 studies contained a total of 1962 patients with erectile dysfunction and 1752 healthy controls. The results of our meta-analysis showed that G894T correlated with an increased risk erectile dysfunction under both the allele and dominant models (allele: OR = 1.556, 95% CI = 1.064–2.275, P = 0.023; dominant: OR = 1.613, 95% CI = 1.050–2.476, P = 0.029). A similar association was found between T-786C and erectile dysfunction under the allele model (OR = 1.679, 95% CI = 1.341–2.102, P < 0.001), but not under the dominant model (all P > 0.05). Our meta-analysis showed that the two single nucleotide polymorphisms in eNOS gene, G894T and T-786C, are strongly associated with the risk of erectile dysfunction.

Hypertension might be a risk factor for erectile dysfunction: a meta-analysis

The study aimed to evaluate whether hypertension was a risk factor for erectile dysfunction (ED). Databases including PubMed and Embase were retrieved to identify studies related to hypertension in ED patients. Odds ratio (OR) and 95% confidence interval (CI) were used as the effect size. Subgroup analyses stratified by total number of enrolled subjects and research regions were performed. Sensitivity analysis was performed by removing a single study at one time. Egger's test was used to evaluate the publication bias. Totally, 40 studies including 121,641 subjects were included in the meta-analysis. As a result, hypertension was closely related to ED (OR = 1.74, 95% CI, 0.63-0.80, p < .01). Subgroup analysis indicated hypertension was the risk factor for ED whatever the participants numbers. When stratified by different regions, hypertension was a risk factor for ED in Africa (OR = 3.35, 95% CI, 1.45-7.77, p < .01), Americas (OR = 1.97, 95% CI, 1.68-2.31, p < 0.01), Asia (OR = 1.46, 95% CI, 1.16-1.84, p < .01) and Europe (OR = 1.83, 95% CI, 1.34-2.49, p < .01), but not in Australia. Hypertension may be a potential risk factor for ED.

Pharmacogenetics of erectile dysfunction: navigating into uncharted waters

Sildenafil and other PDE-5 inhibitors have revolutionized erectile dysfunction (ED) treatment. However, a significant number of patients do not respond or present adverse reactions to these drugs. While genetic polymorphisms may underlie this phenomenon, very little research has been undertaken in this research field. Most of the current knowledge is based on sildenafil, thus almost completely ignoring other important pharmacological therapies. Currently, the most promising genes with pharmacogenetic implications in ED are related to the nitric oxide and cGMP pathway, although other genes are likely to affect the responsiveness to treatment of ED. Nevertheless, the small number of studies available opens the possibility of further exploring other genes and phenotypes related to ED. This article provides a comprehensive overview of the genes being tested for their pharmacogenetic relevance in the therapy of ED.

Endothelial nitric oxide synthase: From biochemistry and gene structure to clinical implications of NOS3 polymorphisms

Nitric oxide (NO) is an important vasodilator with a well-established role in cardiovascular homeostasis. While mediator is synthesized from L-arginine by neuronal, endothelial, and inducible nitric oxide synthases (NOS1,NOS3 and NOS2 respectively), NOS3 is the most important isoform for NO formation in the cardiovascular system. NOS3 is a dimeric enzyme whose expression and activity are regulated at transcriptional, posttranscriptional,and posttranslational levels. The NOS3 gene, which encodes NOS3, exhibits a number of polymorphic sites including single nucleotide polymorphisms (SNPs), variable number of tandem repeats (VNTRs), microsatellites, and insertions/deletions. Some NOS3 polymorphisms show functional effects on NOS3 expression or activity, thereby affecting NO formation. Interestingly, many studies have evaluated the effects of functional NOS3 polymorphisms on disease susceptibility and drug responses. Moreover, some studies have investigated how NOS3 haplotypes may impact endogenous NO formation and disease susceptibility. In this article,we carried out a comprehensive review to provide a basic understanding of biochemical mechanisms involved in NOS3 regulation and how genetic variations in NOS3 may translate into relevant clinical and pharmacogenetic implications.

Genetics of resistant hypertension: a novel pharmacogenomics phenotype

Resistant hypertension (RHTN), defined as an uncontrolled blood pressure despite the use of multiple antihypertensive medications, is an increasing clinical problem associated with increased cardiovascular (CV) risk, including stroke and target organ damage. Genetic variability in blood pressure (BP)-regulating genes and pathways may, in part, account for the variability in BP response to antihypertensive agents, when taken alone or in combination, and may contribute to the RHTN phenotype. Pharmacogenomics focuses on the identification of genetic factors responsible for inter-individual variability in drug response. Expanding pharmacogenomics research to include patients with RHTN taking multiple BP-lowering medications may identify genetic markers associated with RHTN. To date, the available evidence surrounding pharmacogenomics in RHTN is limited and primarily focused on candidate genes. In this review, we summarize the most current data in RHTN pharmacogenomics and offer some recommendations on how to advance the field.

[Genetic aspects of erectile dysfunction]

BACKGROUND

Erectile dysfunction (ED) is a common disorder in man that influences the quality of life of the patient and his partner. Known risk factors for ED comprise diabetes, coronary artery disease, hypertension but also lifestyle modifications such as smoking, diminished physical activity as well as obesity. In this manuscript the current scientific literature about genetics and erectile dysfunction is reviewed.

MATERIALS AND METHODS

A literature search using the databank PubMed covering the topics genetics and erectile dysfunction was performed and relevant papers selected for presentation.

RESULTS

Several aspects of genetics and ED are described in the current literature. Association studies of candidate polymorphisms and ED risk in comparison to healthy controls is a major area of research. Another topic is the genome-wide search for candidate polymorphisms with erectile dysfunction. The paper closes with the presentation of the pharmacogenomic analysis of treatment response to phosphodiesterase-5 inhibitors.

DISCUSSION

The heterogeneous results of genetic association studies are possibly due to small sample sizes of the study population and/or due to ethnic differences of the analyzed populations. This underlines the need for validation of this data in larger prospective multinational multicenter studies.

Endothelial nitric oxide synthase gene polymorphisms and prostate cancer risk in Serbian population

Genome-wide association studies (GWAS) have identified over 46 SNPs associated with human prostate cancer (PCa). Some studies have shown correlation of the nitric oxide synthase (NOS) NOS3 gene polymorphisms with the risk and/or progression of PCa. This study aimed to evaluate the association of NOS3 gene polymorphisms (-786T>C, -764A>G, -714G>T, -690C>T, -649G>A and 894G>T) with PCa risk and progression. 150 patients with PCa, 150 patients with BPH and 100 age-matched healthy controls were recruited in this study. Genotyping of promoter polymorphisms was performed by bi-directional DNA sequencing, and for 894G>T by RFLP analysis. There was no significant association between the alleles and genotypes of these genetic variants and PCa risk. For -786T>C polymorphism, we found that C allele is associated with absence of metastases, assuming dominant genetic model (P = 0.049; OR, 0.50; 95% CI, 0.25-1.00). It was found that, compared with NOS3 -690C>T variant CC genotype, CT and TT genotypes confer decreased risk of developing metastases (dominant model, P = 0.015, OR, 0.24; 95% CI, 0.07-0.88) and show association with low clinical tumour stage, compared with stages T3 and T4 (dominant model, P = 0.046, OR, 0.20; 95% CI, 0.04-1.02). Genetic variants -764A>G, -714G>T, -649G>A were not detected in our study group. There is evidence of an inverse correlation of the NOS3 894G>T minor allele with high serum PSA (>20 ng/ml) (dominant model, P = 0.013, OR, 0.37; 95% CI, 0.17-0.82). Our results suggest that NOS3 gene polymorphisms are genetic susceptibility factors for the progression of PCa and patient outcome.

eNOS [Glu298Asp] polymorphism, erectile function and ocular pressure in type 2 diabetes

BACKGROUND

  Imbalance in nitric oxide (NO), an atheroprotective vasodilator, is associated with endothelial dysfunction, cardiovascular diseases (CVD) and diabetic complications. Various endothelial NO synthase (eNOS) polymorphisms may affect NO bioavailability, thereby promoting adverse cardiovascular milieu.

MATERIALS AND METHODS

  To analyze glucose homeostasis, cardiometabolic phenotype, and micro- and macroangiopathies associated with eNOS G894T gene polymorphism in type 2 diabetes (T2DM). 210 T2DM outpatients (mean age (1SD) 70 (12); diabetes duration 19 (9) years; males:females 64:36%; metabolic syndrome 87%) had insulin sensitivity and b-cell function modelled with HOMA, alongside routine laboratory and endothelin measurements.

RESULTS

  GG, GT and TT genotypes represented 48% (n = 100), 39% (n = 83) and 13% (n = 27). Overall microangiopathy (retinopathy, neuropathy and/or nephropathy) was present in 74%, and overall macroangiopathy (CAD, PAD and/or TIA/stroke) in 45%. The TT genotype did not translate into a more severe vascular phenotype, as TT patients carrying the proposed risk genotype did not suffer a higher rate of micro- and macrovascular complications. On the other hand, erectile dysfunction, present in 60% of males (n = 135), was much more prevalent in TT males: 57% [GG & GT] vs. 93% in TT (p 0.0088). Ocular hypertension/glaucoma frequency (18% of the whole group) was also markedly different, albeit in opposing directions, between eNOS G894T gene polymorphism subgroups: 21% [GG & GT] vs. 0% prevalence (TT; p 0.0057).

CONCLUSIONS

  eNOS G894T gene polymorphism in homozygous TT carriers translates into opposing effects on erectile function (detrimental) and ocular hypertension/glaucoma (protective) in T2DM, without affecting glucose homeostasis determinants or the presence of micro- and macrovascular complications.

Biochemical and genetic markers of erectile dysfunction

Erectile dysfunction (ED) is a very common pathology, affecting over 150 million men worldwide. The pathogenesis is typically multifactorial, involving a kaleidoscope of organic, endocrine, and psychogenic factors. In general, ED is divided into organic and psychogenic impotence, but most men with organic etiologies have an associated psychogenic component. Given the high frequency of this pathology, the identification of biochemical and genetic correlates and/or markers is of pivotal interest not only for treating preciously these patients and preventing serious psychological consequences but also for the high risk for occult cardiovascular disease (CVD) that often accompanies or follows this pathology. A variety of cardiovascular risk factors have been associated with both the onset and the severity of ED, including markers of endothelial function, thrombosis, and especially dyslipidemia, so that their measurement should now be considered as an important part of the increased global cardiometabolic risk profile in patients with ED. While nitric oxide (NO), asymmetric dimethylarginine (ADMA), and endothelin (ET) hold some promises as biochemical markers of both CVD and ED, there are several technical and clinical drawbacks that make their measurement overall meaningless in the clinical practice. As regards genetic polymorphisms, controversial results have been provided so far. Although some genetic markers were consistently associated with ED, other studies failed to demonstrate significant associations, highlighting a substantial bias in standardization of methodologies and patient enrolment. Nevertheless, further research in this area should be encouraged, since the first promising evidence that gene therapy might be effective to restore the decline in ED has been provided in the animal model.

Sexual dysfunction in male schizophrenia: influence of antipsychotic drugs, prolactin and polymorphisms of the dopamine D2 receptor genes

Aim: Sexual dysfunction induced by antipsychotic drug treatment is under investigated and under reported. This study aimed to determine the influence of genetic polymorphisms in the D2 dopamine receptor (DRD2) and endothelial nitric oxide synthase (eNOS) genes, and the possible role of blood prolactin concentrations on sexual function in schizophrenic patients. Materials & methods: Male remitted schizophrenic patients (n = 100), who were living with a sexual partner and receiving antipsychotic drug monotherapy for at least 6 months, were assessed for sexual and erectile dysfunction using the Arizona Sexual Experience Scale and the five-item version of the International Index of Erectile Function. Blood samples were taken for plasma prolactin determination and genotyped for four polymorphisms: DRD2 (-141C Ins/Del and Taq1A) and eNOS gene (G894T and T-786C). Results: The -141C Ins/Del, but not Taq1A, polymorphism of the DRD2 gene was significantly associated with sexual dysfunction with the del allele being less frequent in sexual dysfunction subjects. Neither of the eNOS polymorphisms, G894T or T-786C, was significantly associated with sexual or erectile dysfunction. Prolactin concentrations were significantly higher in patients with erectile dysfunction but did not reach significance in those with sexual dysfunction. Prolactin was also reduced in -141C Del allele carriers. The frequency and severity of sexual dysfunction in the patients receiving typical antipsychotics was significantly greater than those receiving risperidone or clozapine, while prolactin concentrations were significantly higher in subjects receiving risperidone compared with those receiving clozapine or typical antipsychotics. Conclusion: This is the first evidence indicating that antipsychotic drug treatment in men is associated with a variant in the DRD2 gene in which the -141C Del allele might be a protective factor. While this may, in part, be mediated by effects on prolactin, other factors are likely to contribute to the greater sexual dysfunction in patients receiving typical antipsychotics.

Original submitted 25 January 2011; Revision submitted 21 March 2011

Endothelial nitric oxide synthase gene polymorphism (Glu298Asp) and acute pulmonary hypertension post cardiopulmonary bypass in children with congenital cardiac diseases

BACKGROUND

Intra-cardiac repair of congenital cardiac diseases in children with left-right shunt is often associated with acute elevation of pulmonary artery pressure following cardiopulmonary bypass. We studied the correlation between the Glu298Asp polymorphism of the endothelial nitric oxide synthase gene and pulmonary hypertension in children with congenital cardiac diseases.

METHODS AND RESULTS

A total of 80 children with congenital cardiac diseases at a median age of 3.8 years, ranged 0.1-36.2 years, and 136 controls were enrolled. Most patients presented with significant left-to-right shunt - pulmonary-to-systemic blood flow of 2.8, with a range from 0.6 to 7.5. In all, 40 out of 80 children showed pulmonary hypertension with mean pressure of 42, ranged 26-82, millimetres of mercury. Thirty-one out of 40 children underwent intra-cardiac repair and 15 out of 31 operated patients were found to have an acute elevation of pulmonary artery pressure after cardiopulmonary bypass. The Glu298Asp polymorphism was identified using polymerase chain reaction and restriction fragment length polymorphism. Both in patients and in controls, the genotype distribution corresponded to the Hardy-Weinberg equilibrium. The gene frequency for Glu298Glu, Glu298Asp and Asp298Asp was not different in the control group compared to the patients (Armitage trend test: p = 0.37). The endothelial nitric oxide synthase polymorphism was related to acute post-operative elevation of pulmonary artery pressure (genotypic frequency 53.3 versus 25%; Armitage trend test: p = 0.038). In addition, the allelic frequency of the Glu298Asp was related to post-operative pulmonary hypertension (Fischer's exact test: p = 0.048). The positive predictive value was 71.43%.

CONCLUSION

Patients with left-to-right shunt are more likely to develop acute elevation of pulmonary artery pressure after cardiopulmonary bypass when presenting with the Glu298Asp polymorphism of the gene endothelial nitric oxide synthase. This could be used as a genetic marker for the predisposition for the development of pulmonary hypertension after intra-cardiac repair.

Role of methylenetetrahydrofolate reductase gene polymorphisms (C677T, A1298C, and G1793A) in the development of early onset vasculogenic erectile dysfunction

BACKGROUND AND AIMS

The methylenetetrahydrofolate reductase (MTHFR) gene plays a key role in the metabolism of folate and homocysteine (Hcy) and its mutations have been associated with high serum Hcy level. Elevated serum Hcy has been linked to impaired endothelial function and occlusive vascular disease. We studied the association among the different genotypes of all three MTHFR polymorphisms (C677T, A1298C, and G1793A) and the risk of early-onset vasculogenic erectile dysfunction (VED).

METHODS

We performed a case-control study of 114 men with early-onset VED and 228 age-matched controls. Genotyping of MTHFR gene polymorphisms was performed using polymerase chain reaction restriction fragment length polymorphism (PCR-RLFP) technique. We also measured plasma lipids, Hcy, folate, and vitamin B12 levels.

RESULTS

Patients with early-onset VED had higher serum Hcy levels (12.29 ± 2.32 vs. 9.82 ± 2.35 μmol/L, p = 0.001) and higher prevalence of 677TT homozygocity compared to controls (15.8% vs. 11.4%, p = 0.01). Serum Hcy concentration was significantly higher in individuals with 677TT, 1298CC, and 1793GG genotypes. Subgroup analysis according to severity of ED (mild, moderate, and severe) showed that patients with severe VED had higher serum Hcy levels compared to patients with mild VED (13.48 ± 2.51 vs. 11.21 ± 2.32 μmol/L, p = 0.001).

CONCLUSIONS

Odds ratio seems to demonstrate that individuals with the MTHFR 677TT genotype and the 677TT + 1298AC combined genotype had a 3.16- and 3.89-fold increased risk for developing VED, suggesting a possible association of MTHFR polymorphisms with the risk of early-onset VED.

The impact of irritative lower urinary tract symptoms on erectile dysfunction in aging Taiwanese males

OBJECTIVE

This study assessed the possible associations between lower urinary tract symptoms (LUTS) and erectile dysfunction (ED) in aging Taiwanese males and investigated the impact of various aspects of LUTS on ED.

METHODS

A free health screening for aging males (> or =40 years old) was conducted in Kaohsiung Medical University Hospital. All the subjects had completed clinical data and answered questionnaires. ED and LUTS were assessed by validated symptom scales: the International Index of Erectile Function-5 (IIEF-5) and the International Prostate Symptom Score (IPSS).

RESULTS

A total of 339 eligible patients enrolled in this study with a mean age of 60.1 years old. In multiple logistic regression analysis, age and IPSS (p < 0.001 and p = 0.013, respectively) were significantly associated with ED after controlling other comorbidities. In a further age-adjusted multiple regression analysis, our results showed that irritative symptoms (p = 0.042) have a more significant association with ED than the obstructive symptoms (p = 0.101).

CONCLUSIONS

Our results indicate that age and LUTS are the two most independent risk factors for ED. Aging Taiwanese males with LUTS are at increasing risk for ED, especially for those with significant irritative symptoms.

Endothelial nitric oxide synthase polymorphisms and erectile dysfunction: a meta-analysis

INTRODUCTION

Erectile dysfunction (ED) is a common disorder noted for affecting quality of life. Several studies have reported the influence of endothelial nitric oxide synthase (eNOS) polymorphisms on ED susceptibility. However, results of association studies with individually low statistical power are conflicting.

AIM

Our study aimed to carry out a meta-analysis estimating the association between eNOS variants and the risk of ED.

METHODS

Studies regarding the association between eNOS polymorphisms and ED were searched in Medline and Embase databases. The relevant studies that met the inclusion criteria were eligible for the analysis.

MAIN OUTCOME MEASURES

Five genetic models and a generalized odds ratio (OR(G) ) were used to estimate the association between eNOS G894T and variable number of 27-bp tandem repeats in intron 4 (4 VNTR) and the risk of ED.

RESULTS

Nine articles were included in our meta-analysis. Overall, significant association between the 894T variant and an increased risk of ED was derived for all genetic contrasts except for the recessive model (allele contrast: OR = 1.64, 95% confidence interval [CI]: 1.03-2.60). The meta-analysis based on the OR(G) also produced significant results: OR(G) = 1.64, 95% CI: 1.03-2.61. Significant heterogeneity and publication bias were detected. The cumulative meta-analysis showed the OR increased from 2003 to 2009 and then declined in 2010. Instability in the relative change of OR was observed. Regarding 4 VNTR and its association with ED, the overall analysis showed a lack of significant association (OR = 0.96, 95% CI: 0.72-1.28). No evidence for heterogeneity among studies was observed. Subgroup analysis by ethnicity and recruitment strategy also yielded nonsignificant results.

CONCLUSION

The result supports that G894T variant is associated with an increase in the risk of ED. No evidence for a significant association between 4VNTR and ED is observed. The results of the present meta-analysis should be interpreted with caution. Further confirmation in large and well-designed studies is needed.

Association Analysis of Endothelial Nitric Oxide Synthase G894T Gene Polymorphism and Erectile Dysfunction Complaints in a Population-Based Survey

Introduction

Erectile dysfunction (ED) is a common disorder leading to a serious, negative impact on the quality of the patient’s life. The gene encoding endothelial nitric oxide synthase (eNOS) is an interesting candidate gene for understanding the physiopathology of ED, as it is involved in the catalytic production of nitric oxide (NO), the neurotransmitter that plays a critical role in penile tumescence and erection.

Aim

To evaluate a potential association between the G894T polymorphism in the eNOS gene and ED complaints in a population-based sample in São Paulo, Brazil.

Main Outcome Measures

The prevalence of ED complaints was estimated according to the answer to the question “How would you describe your ability to get and keep an erection that is adequate for satisfactory intercourse?” ED was considered to be present if the response was “sometimes” or “never.”

Methods

A total of 449 men were enrolled in the study and answered an eight-item questionnaire to ascertain sexual performance/ED and satisfaction. The eNOS G894T polymorphism was genotyped using a standard polymerase chain reaction method.

Results

Univariate analysis demonstrated that ED was associated with diabetes, hypertension, sleep apnea severity, increasing age and body mass index, as well as testosterone levels (P &lt;0.05). Forward multiple regression models indicated that age was the only independent factor associated with ED in this population (odds ratio=1.09; 95% CI 1.06–1.11; P &lt;0.0001). Genotypic and allelic analyses provided no evidence for an association between this polymorphism and the risk for ED complaints in this sample. Population stratification did not affect the association test results.

Conclusions

This is the first study to examine the effect of polymorphisms in the eNOS gene and the risk for ED utilizing a case-control approach in the Brazilian population. Our results do not support a major role for eNOS gene polymorphisms in ED in this population.

Pharmacogenetics and pharmacogenomics of sexual dysfunction: current status, gaps and potential applications

Although treatment of different types of sexual dysfunction has improved in the past decade with the introduction of phosphodiesterase type 5 inhibitors and selective serotonin reuptake inhibitors, response rates to these targeted therapies are variable. There are a number of studies in the published literature that provide proof-of-concept that genetic variation contributes to the variable response. Pharmacogenomics will most likely be one part of our therapeutic armamentarium in the future and will provide a stronger scientific basis for optimizing drug therapy on the basis of each patient’s genetic constitution. This article will review English language medical literature on the state-of-the-art genetic polymorphisms of drug targets, transporters and signaling molecules as well as pharmacogenetic studies of sexual dysfunction and suggested possible applications. Collectively, the data demonstrate that pharmacogenomics in the field of sexual medicine is still in its infancy. More research will provide further intriguing new discoveries in years to come.

The associations among eNOS G894T gene polymorphism, erectile dysfunction, and benign prostate hyperplasia-related lower urinary tract symptoms

INTRODUCTION

A number of literature has now identified the role of impaired nitric oxide synthase/nitric oxide pathway in the endothelium as the central to the development of erectile dysfunction (ED) and benign prostate hyperplasia-related lower urinary tract symptoms (BPH/LUTS). Recently a few studies have reported the associations between endothelial nitric oxide synthase (eNOS) G894T gene polymorphisms and ED. However, there has been no report investigating the eNOS G894T genetic susceptibility factor for both ED and BPH/LUTS.

AIM

To investigate the possible associations among eNOS G894T polymorphism, ED, and BPH/LUTS in a Taiwanese population.

MAIN OUTCOME MEASURES

Patients with ED were defined as those having a 5-item International Index of Erectile Function-5 <21.

METHODS

In all, 372 Taiwanese men underwent a free health screening were enrolled. All the men had complete clinical data and questionnaires taken. The eNOS G894T polymorphisms were determined using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

Three hundred seventy-two men had a mean (standard deviation) age of 60.2 (8.8) years. With multivariate analysis, our data identified that aging, diabetes mellitus (DM), and eNOS G894T gene polymorphism were three independent common risk factors for both ED and BPH/LUTS (P < 0.001, P = 0.036, and P = 0.039 for ED; P = 0.034, P = 0.004, and P = 0.016 for BPH/LUTS, respectively). The eNOS 894T allele carriers had significantly higher prevalence of ED (77.9% vs. 60.4%, P = 0.012) and higher International Prostate Symptom score (IPSS) (13.3 +/- 10.7 vs. 9.3 +/- 7.8, P = 0.001) than G allele carriers.

CONCLUSIONS

Our results showed that aging, DM, and eNOS 894T allele carrier gene polymorphism were the three independently common risk factors for both ED and BPH/LUTS in the Taiwanese population. The eNOS 894T allele carriers had significantly higher frequencies of ED and higher IPSS, suggesting that eNOS G894T gene polymorphisms may play an implication as a genetic susceptibility factor for both ED and BPH/LUTS.

Association of coronary artery disease, erectile dysfunction, and endothelial nitric oxide synthase polymorphisms

The purpose of this study was to determine the relationship between erectile dysfunction (ED), coronary artery disease (CAD), and T(-786)C and intron 4 a/b endothelial nitric oxide synthase (eNOS) polymorphisms in 419 patients with suspected or known CAD referred for coronary angiography. The patients had a high prevalence of risk factors for both CAD and ED: hypercholesterolemia (64%), hypertension (74%), diabetes mellitus (25%), obesity (30%), and smoking (63%). Three hundred and twenty-one patients had significant coronary atherosclerosis (luminal diameter narrowing of 50% or more of at least 1 coronary artery), 41 had insignificant coronary stenoses, and 57 patients were found to have coronary arteries without the evidence of atherosclerosis. The prevalence of ED in these groups was 79%, 76%, and 67% (P = NS), respectively. As compared to patients without ED, those with ED exhibited significantly higher probability of having significant coronary atherosclerosis (69% vs 79%, P = 0.04), higher number of significant coronary stenoses (median, 1 vs 2, P = 0.004), and a higher prevalence of a triple-vessel disease (12% vs 25%, P = 0.004). We did not find any relationship between T(-786)C and intron 4 a/b polymorphisms and the manifestation of coronary atherosclerosis or the presence of ED. In conclusion, in patients with numerous cardiovascular risk factors referred for coronary angiography, there was a high prevalence of ED in patients with both the presence and the absence of coronary atherosclerosis. The coincidence of CAD and ED identified patients at increased risk of severe forms of CAD.

The demographic burden of urologic diseases in America

The National Institute of Diabetes and Digestive and Kidney Diseases initiated the Urologic Diseases in America project in 2001 with the goal of quantifying the immense demographic burden of urologic diseases on the American public, in both human and financial terms. This effort was renewed in 2007 with the aim of expanding and deepening analyses of the epidemiology, costs, and quality of medical care in urology. This ongoing commitment recognizes the major public health impact of urologic conditions in the United States. A thoughtful policy response to these changes requires a thorough understanding of the health care resource use and clinical epidemiology relevant to urologic diseases in America. This article details major initial findings from the Urologic Diseases in America project with respect to the demographic impact of the most common benign, malignant, and pediatric urologic conditions.

Sexual dysfunction: the 'prima ballerina' of hypertension-related quality-of-life complications

Sexual dysfunction is currently considered a serious quality-of-life-related health problem, exerting a major impact on patients' and their sexual partners' life. Available data indicate that essential hypertension is a risk factor for sexual dysfunction, as male and female sexual dysfunction is more prevalent in hypertensive patients than normotensive individuals. Several mechanisms have been implicated in the pathogenesis of sexual dysfunction in hypertensive patients, and major determinants include severity and duration of hypertension, age, and antihypertensive therapy. Female sexual dysfunction, although more frequent than its male counterpart, remains largely under-recognized. Older antihypertensive drugs (diuretics, beta-blockers, centrally acting) exert negative results, whereas newer drugs have either neutral (calcium antagonists, angiotensin-converting enzyme inhibitors) or beneficial effects (angiotensin receptor blockers). Erectile dysfunction is related to ischemic heart disease and might be an 'early therapeutic window' of asymptomatic coronary artery disease. It seems of utmost importance for every physician treating hypertensive patients to become familiar with sexual dysfunction (through better education and specific seminars) for the proper management of these patients.

The associations among eNOS G894T gene polymorphism, erectile dysfunction and related risk factors

OBJECTIVE

To investigate the possible correlations among eNOS G894T polymorphism, erectile dysfunction (ED) and related risk factors in a Taiwanese population.

MATERIALS AND METHODS

In all, 151 patients with ED and 77 healthy controls were enrolled. All the men had a complete clinical history taken and laboratory data was collected. To assess erectile conditions the five-item version of the International Index of Erectile Function (IIEF-5) was used. The eNOS G894T polymorphisms were determined using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

In all, 228 men were enrolled with a mean (sd) age of 58.6 (9.7) years. In a univariate analysis, age, serum testosterone level, and the prevalence of diabetes mellitus (DM) and hypertension were significantly different between patients with ED and the healthy controls (P < 0.01). In the multiple logistic regression analysis, DM, age and hypogonadism were three independent risk factors for ED (P = 0.018, P = 0.046 and P = 0.016, respectively). The prevalence of ED in T allele carriers (GT/TT) was significantly greater than in G allele carriers (GG; 80.0% vs 63.3%, P = 0.04). Also the eNOS 894T allele carriers had significantly lower IIEF-5 scores than the eNOS 894G allele carriers, at 13.2 (5.3) vs 15.7 (6.1) (P = 0.01) and it was associated with increment of T allele number (11.0 (5.6) vs 13.6 (5.2) vs 15.7 (6.1); P = 0.03).

CONCLUSION

Our results indicate that DM, age and hypoganadism are three significant independent risk factors for ED. Also, in the Taiwanese population, the eNOS 894T allele carriers are at greater risk of ED, both in prevalence and severity, and this might be a factor of genetic susceptibility.

Association between the insertion/deletion polymorphism of the angiotensin-converting enzyme gene and erectile dysfunction in patients with metabolic syndrome

This study was designed to investigate whether angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism is associated with erectile dysfunction (ED) in Russian men with metabolic syndrome (MS). A total of 331 men with MS were studied. All patients underwent complex evaluation including the International Index of Erectile Function (IIEF) questionnaire. The ACE I/D polymorphism was determined by polymerase chain reaction. Overall, 182 men (55.0%) had ED according to the IIEF erectile function domain score. In the ED group, the prevalence of DD genotype was found to be significantly higher compared to the non-ED group (P<0.001). In both groups, patients with DD genotype were significantly younger than patients with other genotypes (P<0.001). In addition, in the ED group, the disease affected patients with DD genotype at a significantly younger age (P<0.001). Obtained results give evidence to support the finding that the D allele is a risk factor for the micro- and macrovascular diseases.

Sexual dysfunction in essential hypertension: myth or reality?

Erectile dysfunction is currently considered a condition with high prevalence in the general population, exerting a major impact on patients' and their sexual partners' quality of life. Available data indicate that hypertension represents a risk factor for erectile dysfunction, which is more frequent in hypertensive compared with normotensive subjects. The pathophysiologic basis of erectile dysfunction in hypertension is under thorough investigation, and several mechanisms have been proposed. Erectile dysfunction has also been related to cardiovascular risk factors and might be used as a marker of cardiovascular disease in the future. Although male sexuality has been studied rather extensively, female sexual dysfunction in hypertension is underexplored. Recently published hypertension guidelines either ignore or superficially address sexual dysfunction, underlining the need for more attention and better education of health care professionals on this issue.

Pharmacology of erectile dysfunction in man

Erectile dysfunction (ED) is defined as the consistent or recurrent inability of a man to attain and/or maintain a penile erection sufficient for sexual activity (2nd International Consultation on Sexual Dysfunction-Paris, June 28th-July 1st, 2003). Following the discovery and introduction of sildenafil, research on the mechanisms underlying penile erection has had an enormous boost and many preclinical and clinical papers have been published in the last 5 years. This review is structured in order to give the reader an overview of the clinical and preclinical data available on the peripheral regulation of and the mediators involved in human penile erection. The most widely accepted risk factors for ED are discussed. The article is focused on human data, and the safety and effectiveness of the 3 commercially available Phosphodiesterase-5 (PDE5) inhibitors used to treat ED are also discussed.

ORIGINAL RESEARCH—BASIC SCIENCE: Polymorphism of Endothelial Nitric Oxide Synthase Gene in Patients with Erectile Dysfunction

INTRODUCTION

Endothelial-derived nitric oxide (NO), which is produced by endothelial nitric oxide synthase (eNOS) in response to increased blood flow, maintains the tumescence phase of erection. The eNOS gene is located on the seventh somatic chromosome and the polymorphism of this gene has been reported to cause changes in the structure of enzyme system, resulting in disturbance of its activity.

AIM

The aim of this prospective study is to evaluate the relationship between polymorphism of eNOS gene and erectile dysfunction (ED).

METHODS

Thirty patients with ED (mean age: 58.7 +/- 9.97, range: 39-74 years) and 25 voluntary controls (mean age: 56.44 +/- 7.58, range: 47-72 years) were enrolled to the study. Patients with ED were evaluated with International Index of Erectile Function (IIEF) questionnaire, routine blood tests for systemic vascular risk factors, and color Doppler ultrasonography while potency of the control group were only assessed with IIEF questionnaire. The presence of polymorphism of eNOS gene was determined in both groups by polymerase chain reaction in the fourth intron of the seventh somatic chromosome that encodes eNOS gene.

RESULTS

The incidences of diabetes mellitus and coronary artery disease were statistically higher in the ED group (P = 0.023 and 0.029, respectively) while mean IIEF score was significantly lower (P = 0.001). Evaluation with color Doppler ultrasonography revealed penile arterial insufficiency in six cases, cavernosal insufficiency in 19 cases, and mixed vascular insufficiency in five cases. The distributions of three eNOS genotypes (eNOS4b/b, eNOS4a/b, and eNOS4a/a) among ED patients and controls were similar (P > 0.05). However, eNOS4a/b genotype was statistically higher in diabetics (P = 0.042). Also, 80% of the patients with severe ED and 54.5% of the diabetic patients with ED had eNOS4a/b genotype.

CONCLUSION

In our study, no correlation was detected between the polymorphism of eNOS gene and ED. However, 80% of the patients with severe ED and 54.5% of the diabetic patients with ED had eNOS4a/b genotype. Based on our data, it seems that diabetic patients with ED tend to have more eNOS4a/b genotype.