Association of eNOS gene polymorphisms with renal disease in Caucasians with type 2 diabetes

Association between nitric oxide synthase (NOS3) gene polymorphisms and diabetic nephropathy: An updated meta-analysis

Polymorphisms located within NOS3 gene have been investigated as susceptibility variants for diabetic nephropathy (DN) in type 2 diabetes mellitus (T2DM) in a large number of studies. However, these previous articles yielded inconsistent results and we aimed at elucidating the impact of NOS3 variants on DN risk in T2DM by conducting an updated systematic data synthesis. A total of 36 studies (12,807 participants) were selected for qualitative data synthesis, while 33 records with 11,649 subjects were included in the meta-analysis. The pooled analysis demonstrated the association of minor alleles of rs2070744 and rs1799983 with an increased susceptibility to DN (P < 0.001 and P = 0.015 for allelic model, respectively). For both of these variants, a significant effect of subgrouping according to ethnicity was found. Rs869109213 displayed an association with DN susceptibility, with pooled effect measures indicating a predisposing effect of the minor allele a (Prec = 0.002, ORrec = 1.960, 95%CI 1.288-2.983; Paavs. bb = 0.001, ORaavs. bb = 2.014, 95%CI 1.316-3.083). These findings support the effects of NOS3 variants on the risk of developing DN in T2DM.

Associations between the polymorphisms of main components in PI3K/Akt pathway and risk of diabetic kidney disease: A meta-analysis

AIMS

Diabetic kidney disease (DKD) is a severe microvascular complication frequently associated with type 1 and type 2 diabetes mellitus. The objective of this work was to evaluate the relevance of PI3K/Akt pathway polymorphisms and DKD susceptibility by a meta-analysis.

METHODS

Case-control studies related to the relationship between PI3K/Akt pathway polymorphisms and DKD risk were searched from Pubmed, Embase, Cochrane Library, SINOMED, CNKI, and Wanfang databases. Statistical analysis and heterogeneity test were conducted by Review Manager 5.4.

RESULTS

Totally, 52 eligible studies were enrolled, including seven single nucleotide polymorphisms (SNPs) for four genes in the PI3K/AKT pathway (GNB3: rs5443; eNOS: rs1799983, rs869109213, rs2070744; IL-6: rs1800795, rs1800796; TNFα: rs1800629). The "M" allele of eNOS rs1799983 was related to the increased risk of DKD under random effects model, especially in Asian population (Overall:M vs. W: I2  = 75%, OR = 1.29, 95%CI 1.07-1.56; MM + WM vs. WW: I2  = 75%, OR = 1.50, 95%CI 1.21-1.86). The "M" allele of eNOS rs869109213 was implicated with higher prevalence of DKD under random effects model, especially in Asian population (Overall:M vs. W: I2  = 63%, OR = 1.43, 95%CI 1.22-1.68; MM + WM vs. WW: I2  = 50%, OR = 1.36, 95%CI 1.16-1.58; MM vs. WM + WW: I2  = 59%, OR = 2.20, 95%CI 1.41-3.43). The "M" allele of eNOS rs2070744 was implicated with higher prevalence of DKD under random effects model, especially in Indian population (Overall: M vs. W: I2  = 47%, OR = 1.35, 95%CI 1.15-1.59; MM + WM vs. WW: I2  = 45%, OR = 1.32, 95%CI 1.07-1.62; MM vs. WM + WW: I2  = 65%, OR = 2.29, 95%CI 1.39-3.77). The "M" allele of IL-6 rs1800796 was predominately associated with higher DKD risks under random effects model, especially in Asian population (Overall: M versus W: I2  = 23%, OR = 1.49, 95%CI 1.21-1.84; MM + WM vs. WW: I2  = 1%, OR = 1.43, 95%CI 1.15-1.77; MM + WM vs. WW: I2  = 71%, OR = 2.77, 95%CI 1.09-7.06).

CONCLUSIONS

This meta-analysis indicated that polymorphisms in the PI3K/Akt pathway in eNOS rs1799983, rs869109213, rs2070744, and IL-6 rs1800796 were related to the increased risk of DKD.

The genetic side of diabetic kidney disease: a review

BACKGROUND

Diabetic kidney disease (DKD) is one of the most common complications of diabetes, with approximately 30-40% of patients with type 1 diabetes mellitus and 20% of patients with type 2 diabetes mellitus eventually developing DKD. If DKD is not controlled in the early clinical stage and proteinuria develops, the disease will progress to end-stage renal disease. The pathogenesis of DKD remains largely unknown and is multifactorial, likely due to interactions between genetic and environmental factors. Familial clustering also supports a critical role of hereditary factors in DKD. The development of gene detection technology has promoted the exploration of DKD susceptibility genes in different cohorts of patients with diabetes. Identifying susceptibility genes can provide insights into the pathogenesis of DKD, as well as a basis for its clinical diagnosis and therapy.

RESULTS

Numerous candidate gene loci have been found to be associated with DKD, many of which play critical regulatory roles in the pathogenesis of this disease, including genes involved in glycol-metabolism, lipid metabolism, the renin-angiotensin-aldosterone system, inflammation and oxidative stress. In this review, we summarize the functions of several susceptibility genes involved in the development of DKD.

CONCLUSION

Based on our findings, we recommend that studying susceptibility gene polymorphisms can lead to a better understanding of the pathogenesis of DKD and could help prevent this disease or improve its outcomes.

Recent Progress in Genetics and Epigenetics Research on Diabetic Nephropathy in Malaysia

Diabetic nephropathy is a multifactorial disease. Gene susceptibility, as well as environmental exposure, plays an important role in disease progression. Malaysia is reported to be among the world's second-fastest-growing rates of kidney failure. Diabetic nephropathy has become the main cause of end-stage renal disease in Malaysia. This article is aimed at reviewing genetic studies conducted among diabetic nephropathy patients in the Malaysian population. This review was conducted by searching PubMed, MEDLINE, and Google Scholar databases to identify all relevant papers published in English from March 2022 to April 2022, using the following keywords: diabetes, type 2 diabetes, diabetic nephropathy, diabetic kidney disease, and Malaysia. The case-control study among diabetic patients with and without diabetic nephropathy showed a significant association with diabetic nephropathy in CNDP1, NOS3, and MnSOD genes. In the ethnic subgroup analysis, significant differences for diabetic nephropathy in terms of diabetes duration (≥10 years) were observed for CCL2 rs3917887, CCR5 rs1799987, ELMO1 rs74130, and IL8 rs4073. The IL8 rs4073 was associated only with the Indians, while the CCR5 rs1799987 was associated with the Chinese. In Malays, SLC12A3 Arg913Gln polymorphism and ICAM1 K469E (A/G) polymorphism were found to be associated with diabetic nephropathy. Studies on gene-environment interactions have suggested significant genetic and environmental factors such as smoking, waist circumference, and sex for eNOS rs2070744, PPARGC1A rs8192678, KCNQ1 rs2237895, and KCNQ1 rs2283228 with kidney disease. The genetic variants' contributions differed across ethnic groups. Therefore, a study to validate the genetic variants that are found to be associated with different ethnicities in Malaysia may be important in future studies.

Epithelial nitric oxide synthases (eNOS) 894 G < T polymorphism and diabetic nephropathy susceptibility: A meta-analysis

Objective

To investigate the epithelial nitric oxide synthases (eNOS) 894 G < T polymorphism and diabetic nephropathy (DN) susceptibility by pooling the open published data.

Methods

Studies relevant to eNOS 894 G < T polymorphism and DN susceptibility published in PubMed, EMBASE, Medline, CNKI, and Wanfang databases were systematically screened by using the text words of endothelial nitric oxide synthase, eNOS, NOS-3, G894T, rs179983, polymorphism, diabetic nephropathy, and DN. The correlation between eNOS 894 G < T polymorphism and DN susceptibility was demonstrated by odds ratio (OR) and corresponding 95% confidence interval (95% CI). The data were combined through fixed or random effect model according to statistical heterogeneity. The publication bias was assessed by Begg’s funnel plot and Egger’s line regression test.

Results

Twenty-six case-control studies relevant to eNOS 894 G < T polymorphism and DN susceptibility were identified by electronic searching of the related databases. Type 2 diabetes mellitus (T2MD) patients with T allele had increased susceptibility to DN compared with G allele under homologous gene model (TT vs GG) (OR = 1.40, 95% CI: 1.16–1.69, p = 0.001), dominant gene model (TT + GT) vs GG (OR = 1.61, 95% CI: 1.30–2.00, p = 0.000) and recessive gene model TT vs (GT + GG) (OR = 1.39, 95% CI: 1.16–1.66, p = 0.000). Publication bias was not statistically significant for homologous and recessive gene model.

Conclusion

Based on the present evidence, DN risk was increased in T2MD cases with T allele compared to G allele.

Evaluation of Association Studies and Meta-Analyses of eNOS Polymorphisms in Type 2 Diabetes Mellitus Risk

Background: Numerous studies reported the associations between endothelial nitric oxide synthase (eNOS) polymorphisms (4b/a VNTR (rs869109213), G894T (rs1799983) and T786C (rs2070744)) and type 2 diabetes mellitus (T2DM) risk. However, the conclusions were incongruent. Moreover, since no published meta-analyses were performed, a key issue regarding false-positive results needs to be addressed. Furthermore, four new articles have been published on these issues. Therefore, an updated meta-analysis was conducted to further explore these associations.

Objectives: To investigate the association between eNOS 4b/a, G894T and T786C polymorphisms and T2DM risk.

Methods: Studies were searched by using the PubMed, China National Knowledge Infrastructure (CNKI), Medline, Embase, International Statistical Institute (ISI) and the China Wanfang databases. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the associations using five genetic models. Furthermore, the false-positive report probability (FPRP), Bayesian false discovery probability (BFDP), and the Venice criteria were employed to assess the credibility of statistically significant associations.

Results: Overall, the eNOS 4b/a polymorphism was associated with a significantly decreased T2DM risk in Asians (bb vs. aa: OR = 0.44, 95% CI = 0.23–0.84; ab + bb vs. aa: OR = 0.45, 95% CI = 0.24–0.86; bb vs. aa + ab: OR = 0.73, 95% CI = 0.59–0.91; b vs. a: OR = 0.71, 95% CI = 0.57–0.88); the eNOS G894T polymorphism was associated with a significantly increased T2DM risk in Asians (GT vs. GG: OR = 1.52, 95% CI = 1.15–2.01; GT + TT vs. GG: OR = 1.52, 95% CI = 1.15–2.01; T vs. G: OR = 1.39, 95% CI = 1.09–1.76); the eNOS T786C polymorphism was associated with a significantly increased T2DM risk in Indian (TC vs. TT: OR = 1.93, 95% CI = 1.27–2.94; TC + CC vs. TT: OR = 2.06, 95%CI = 1.26–3.36; C vs. T: OR = 1.90, 95%CI = 1.17–3.08). However, when a sensitivity analysis was performed after excluding low quality and Hardy–Weinberg Disequilibrium (HWD) studies, no significant association was found for the eNOS G894T polymorphism. After credibility assessment, we identified “less-credible positive results” for the statistically significant associations in the current meta-analysis.

Conclusion: In conclusion, this article suggests that all substantial relationships between eNOS 4b/a, G894T, and T786C polymorphisms and T2DM risk are most likely due to false positive results rather than real connections or biological variables.

Role of eNOS and TGFβ1 gene polymorphisms in the development of diabetic nephropathy in type 2 diabetic patients in South Indian population

Background

Diabetic nephropathy is known to be a leading complication of diabetes mellitus, characterized by diverse aspects such as high urinary albumin level, elevated blood pressure, and genetic susceptibility leading to end-stage renal disease. The current study was carried out to investigate the association of eNOS and TGFβ1 gene polymorphisms in the progression of diabetic nephropathy among type 2 diabetic patients in the South Indian population. The eNOS and TGFβ1 genetic variants were genotyped in 280 T2DM patients, 140 with DN, 140 without DN, and 140 controls. Genotyping was performed using ARMS PCR and the genomic variants were confirmed by the Sanger sequencing method.

Results

A significant (p < 0.05) association was observed in the genotypic frequencies of eNOS (G > T) polymorphism in the T2DM patients with diabetic nephropathy when compared to controls. The frequency of TT (heterozygous) genotype was observed to increase in patients with type 2 diabetes and DN when compared to the diabetic patients without DN and controls. This indicates that diabetic patients with TT genotype are at an increased risk to develop DN. However, TGFβ1 (G > C) polymorphism did not show any association in the allele and genotypic frequencies with DN when compared with T2DM and controls.

Conclusion

The results of the study propose a strong influence of TT genotype of eNOS gene be significantly linked with diabetic nephropathy in T2DM patients. Whereas no association was examined concerning TGFβ1 gene polymorphism and DN. Nevertheless, large sample size studies are required to confirm the part of these genetic variants in the development of DN.

Association of eNOS and MCP-1 Genetic Variants with Type 2 Diabetes and Diabetic Nephropathy Susceptibility: A Case-Control and Meta-Analysis Study

Type 2 diabetes (T2D) and its secondary complications result from the complex interplay of genetic and environmental factors. To understand the role of these factors on disease susceptibility, the present study was conducted to assess the association of eNOS and MCP-1 variants with T2D and diabetic nephropathy (DN) in two ethnically and geographically different cohorts from North India. A total of 1313 subjects from two cohorts were genotyped for eNOS (rs2070744, rs869109213 and rs1799983) and MCP-1 (rs1024611 and rs3917887) variants. Cohort-I (Punjab) comprised 461 T2D cases (204 T2D with DN and 257 T2D without DN) and 315 healthy controls. Cohort-II (Jammu and Kashmir) included 337 T2D (150 T2D with DN and 187 T2D without DN) and 200 controls. Allele, genotype and haplotype frequencies were compared among the studied participants, and phenotype-genotype interactions were determined. Meta-analysis was performed to investigate the association between the selected variants and disease susceptibility. All three eNOS variants were associated with 1.5-4.0-fold risk of DN in both cohorts. MCP-1 rs1024611 conferred twofold risk towards DN progression in cohort-II, while rs3917887 provided twofold risk for both T2D and DN in both cohorts. eNOS and MCP-1 haplotypes conferred risk for T2D and DN susceptibility. Phenotype-genotype interactions showed significant associations between the studied variants and anthropometric and biochemical parameters. In meta-analysis, all eNOS variants conferred risk towards DN progression, whereas no significant association was observed for MCP-1 rs1024611. We show evidences for an association of eNOS and MCP-1 variants with T2D and DN susceptibility.

Genetic and epigenetic polymorphisms of eNOS and CYP2D6 in mainland Chinese Tibetan, Mongolian, Uygur, and Han populations

Cytochrome P450 2D6 (CYP2D6) and endothelial nitric oxide synthase (eNOS) are important in the cardiovascular disease susceptibility and drug response. The methylation of cytosine in the promoter of genes could influence expression. The interindividual differences of drug response could only be explained partly by the polymorphisms of drug disposition genes. This study was aimed to investigate the genetic and epigenetic polymorphisms of CYP2D6 and eNOS in Chinese Tibetan, Mongolian, Uygur, and Han volunteers. Blood samples were collected from 842 unrelated Chinese healthy subjects (323 Tibetan, 134 Mongolian, 162 Uygur, and 223 Han) for genotyping and part of the DNA samples were subjected to cytosine methylation analysis. Significant genetic and epigenetic interethnic polymorphisms of eNOS and CYP2D6 were found in the four Chinese groups. The 4b-G-T wild-type haplotype of eNOS was the most common in Chinese Tibetan (87.1%), Mongolian (79.9%), Uygur (76.4%), and Han (79.5%), respectively. eNOS T-786C creates a new CpG site and a significantly higher methylation level was found in -786CC than that in -786TC in Chinese Han (P = 0.0485) and total Chinese (P = 0.0104). CYP2D6 A-678 (rs28633410) makes the symmetrical CpG site changed to be an asymmetrical CpA site, and the methylation level of cytosine in the CpG context of G-678A was significantly higher than that in the CpA. The results of the present study could be useful for understanding the interindividual disparity of cardiovascular disease susceptibility and drug response among different Chinese ethnic groups and would provide more evidences for the precise medication of Chinese.

Association of endothelial nitric oxide synthase (eNOS) and norepinephrine transporter (NET) genes polymorphism with type 2 diabetes mellitus

Genetic factors in combination with environmental factors play a critical role in the development type 2 diabetes mellitus (T2DM) which is growing as an epidemic globally. In present study we aim to assess the association of eNOS (G894T, rs1799983) and NET (G1287A, rs5569) genes polymorphism with T2DM. A case-control study including a total of 400 North Indian subjects (200 T2DM cases and 200 controls) was performed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach to analyze genetic polymorphism. Alleles/genotype frequencies between cases and controls were compared using χ² and Student's t-tests. Odds ratios and 95% confidence intervals were calculated by logistic regression to assess the relative association between disease and genotypes. In case of NET gene, GG (P = 0.002 in T2DM males, 0.053 in overall T2DM cases) genotype and G allele (P = 0.003 in T2DM males, 0.027 in overall T2DM cases) were found to be a positive risk factors and AG genotype (P = 0.012 in T2DM males) and A allele (P = 0.003 in T2DM males, P = 0.027 in overall T2DM cases) as negative risk factor for T2DM. No association of eNOS gene polymorphism was found with T2DM (P values of all genotypes and alleles were greater than 0.05). NET gene polymorphism might be associated with the risk of T2DM whereas; eNOS gene polymorphism do not confer any risk of T2DM in North Indian Ethnic group. It is hoped that understanding genetic causes of T2DM will lead to earlier diagnosis, preventive measures and more effective and specific treatment.

Association of eNOS and ACE gene polymorphisms as a genetic risk factor in gestational diabetes in Iranian women

Background

Gestational diabetes mellitus (GDM) is the most popular metabolic disease during pregnancy. The aim of the present study was to investigate any possible association between eNOS Glu298Asp and ACE I/D gene polymorphisms and the risk of GDM in a group of Iranian pregnant women.

Methods

In this case-control study 204 pregnant women were recruited (94 cases and 110 controls). Genomic DNA was isolated from whole blood and genotyping was performed by the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR- RFLP) and only PCR for eNOS and ACE polymorphisms respectively.

Results

Frequencies of GT and TT genotype of eNOS polymorphism among women with and without GDM were 67.90% vs. 74.47 and 7.41% vs. 8.51% respectively (P = 0.4). Corresponding figures for DD genotype of ACE polymorphism among GDM patients was more than that in healthy women (51.65% vs. 63.81% respectively). Conversely, ACE heterozygote genotype was more common in diabetic women (35.16% vs. 26.67% respectively). Although these differences were not statistically significant (P = 0.2).

Conclusions

Our study showed that there is no association between the presence of eNOS and ACE gene polymorphisms and developing gestational diabetes mellitus among pregnant women in our population. Further longitudinal and multicenter studies should be carried out to assess the exact metabolic effects of these polymorphisms.

NOS3 Polymorphisms and Chronic Kidney Disease

Chronic kidney disease (CKD) is a multifactorial pathophysiologic irreversible process that often leads to a terminal state in which the patient requires renal replacement therapy. Most cases of CKD are due to chronic-degenerative diseases and endothelial dysfunction is one of the factors that contribute to its pathophysiology. One of the most important mechanisms for proper functioning of the endothelium is the regulation of the synthesis of nitric oxide. This compound is synthesized by the enzyme nitric oxide synthase, which has 3 isoforms. Polymorphisms in the NOS3 gene have been implicated as factors that alter the homeostasis of this mechanism. The Glu298Asp polymorphisms 4 b/a and -786T>C of the NOS3 gene have been associated with a more rapid deterioration of kidney function in patients with CKD. These polymorphisms have been evaluated in patients with CKD of determined and undetermined etiology and related to a more rapid deterioration of kidney function.

eNOS Glu298Asp Polymorphism and Endothelial Dysfunction in Patients with and without End-stage Renal Disease

BACKGROUND

Chronic kidney diseases are known to influence nitric oxide metabolites (NOx) and asymmetric dimethylarginine (ADMA), though the exact mechanism is still poorly understood.

AIMS

The purpose of the present study was to examine eNOS Glu298Asp gene polymorphism, plasma NOx and ADMA concentration in subjects with and without End-stage Renal Disease.

STUDY DESIGN

Case-control study.

METHODS

In this study, genotype distributions of Glu-298Asp in exon 7 of the eNOS gene polymorphisms in 130 hemodialysis and 64 peritoneal dialysis patients were compared with 92 controls. NOx was measured by using the Griess reaction while arginine, ADMA and SDMA measurements were performed by HPLC. Genotyping for eNOS Glu298Asp polymorphism was detected with the polymerase chain reaction and/or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.

RESULTS

When the genotype frequencies of TT and GT genes were compared between both groups, there was no detected statistically important difference, even-though a TT genotype frequency was 27 (20.8%) versus 17 (26.6%), GT heterozygote genotype frequency was 52 (40%) versus 22 (34.4%), and GG homozygote genotype frequency was 51 (39.2%) versus 25 (39.1%), respectively (p>0.05). NOx, SDMA and ADMA concentrations were significantly elevated in subjects with hemodialysis patients as compared to their corresponding controls. Whereas nitrite was found to be significantly decreased in the patient with peritoneal dialysis.

CONCLUSION

Not observed any connection between the Glu298Asp polymorphism in the eNOS gene and end-stage Renal Diseases in our study population under different dialysis treatments. However, higher ADMA and SDMA concentrations in subjects with ESRD support the existing hypothesis that NOx overproduction affects endothelial dysfunction. Thus, the reduction of ADMA and SDMA concentrations might play a protective role in ESRD patients.

Endothelial nitric oxide synthase gene polymorphisms and risk of diabetic nephropathy: a systematic review and meta-analysis

Background

Nitric oxide (NO) has numerous functions in the kidney, including control of renal and glomerular hemodynamics, by interfering at multiple pathological and physiologically critical steps of nephron function. Endothelial NOS (eNOS) gene has been considered a potential candidate gene to diabetic nephropathy (DN) susceptibility. Endothelial nitric oxide synthase gene (eNOS-3) polymorphisms have been associated with DN, however some studies do not confirm this association. The analyzed polymorphisms were 4b/4a, T-786C, and G986T.

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement was used in this report. Case–control studies that had diabetic patients with DN as cases and diabetic patients without nephropathy as controls, as well as that evaluated at least one of the three polymorphisms of interest were considered eligible. All studies published up until December 31^st, 2012 were identified by searching electronic databases. Hardy-Weinberg equilibrium assessment was performed. Gene-disease association was measured using odds ratio estimation based on the following genetic contrast/models: (1) allele contrast; (2) additive model; (3) recessive model; (4) dominant model and (4) co-dominant model.

Results

Twenty-two studies were eligible for meta-analysis (4b/a: 15 studies, T-786C: 5 studies, and G984T: 12 studies). Considering 4b/a polymorphism, an association with DN was observed for all genetic models: allele contrast (OR = 1.14, CI: 1.04-1.25); additive (OR = 1.77, CI: 1.37-2.28); recessive (OR = 1.77, CI: 1.38-2,27); dominant (OR = 1.12, CI: 1.01-1.24), with the exception for co-dominance model. As well, T-786C polymorphism showed association with all models, with exception for co-dominance model: allele contrast (OR = 1.22, CI: 1.07-1.39), additive (OR = 1.52, CI: 1.18-1.97), recessive (OR = 1.50, CI: 1.16-1.93), and dominant (OR = 1.11, CI: 1.01-1.23). For the G894T polymorphism, an association with DN was observed in allelic contrast (OR = 1.12, CI: 1.03-1.25) and co-dominance models (OR = 1.13, CI: 1.04-1.37).

Conclusions

In the present study, there was association of DN with eNOS 4b/a and T-786C polymorphism, which held in all genetic models tested, except for co-dominance model. G894T polymorphism was associated with DN only in allele contrast and in co-dominance model. This data suggested that the eNOS gene could play a role in the development of DN.

Interaction between the NOS3 gene and obesity as a determinant of risk of type 2 diabetes: the Atherosclerosis Risk in Communities study

Endothelial nitric oxide synthase 3 (NOS3) catalyzes the production of nitric oxide from L-arginine in endothelial cells. Obesity is a modifiable risk factor for diabetes, and obese individuals have been reported to have reduced nitric oxide availability compared to controls whose weight is in the normal range. Since homozygous carriers of the NOS3 G894T variant are predicted to have decreased enzyme activity, the association between NOS3 genotype and type 2 diabetes, and possible effect modification by body mass index (BMI) were evaluated. The prevalence of diabetes and BMI was determined at baseline in 14,374 participants 45-66 years of age from the prospective biracial population-based Atherosclerosis Risk in Communities (ARIC) Study of the development of atherosclerosis in four communities in the United States. Individuals with a BMI ≥30 kg/m(2) were considered obese. Those subjects not meeting the case definition were the comparison groups for the 728 African American and 980 white participants with diabetes. Multivariable logistic regression models adjusted for age, sex, and field center were used to test for main genetic effects and interaction with obesity. Although the NOS3 G894T variant was not independently associated with diabetes in either African Americans or whites, significant interaction between BMI and the NOS3 polymorphism indicated that obesity was an effect modifier of diabetes risk for white individuals with the TT genotype (odds ratio (OR) for interaction = 1.65, p = 0.04). In stratified analyses, homozygosity for the NOS3 T allele in obese white participants but not in those whose BMI <30 kg/m(2) was associated with an elevated risk of diabetes (OR = 1.47, p = 0.02) when compared to the common GG genotype. These results suggest that interaction between obesity and NOS3 genotype may be a determinant of diabetes case status in whites in the ARIC cohort. Replication in other populations will be required to confirm these observations.

Relationship of endothelial nitric oxide synthase (eNOS) gene polymorphisms with diabetic retinopathy in Caucasians with type 2 diabetes

BACKGROUND

Nitric oxide synthesized by endothelial nitric oxide synthase (eNOS) plays a key role in the regulation of endothelial function, and controversial results regarding the association of eNOS gene polymorphisms with diabetic complications have been reported.

MATERIALS AND METHODS

In this case-control study, the relationship of the -786T/C, the VNTR intron 4 a/b and the 894G/T (Glu298Asp) polymorphisms in the eNOS gene with the presence or severity of diabetic retinopathy was analyzed in 630 Caucasian-Brazilians with type 2 diabetes (434 with and 196 without diabetic retinopathy). Genotyping of eNOS polymorphisms was carried out using the PCR or PCR-RFLP method, and haplotype frequencies were estimated using a Bayesian method.

RESULTS

Genotype and allele frequencies in patients with any degree of diabetic retinopathy or proliferative diabetic retinopathy were not significantly different from those of patients without this complication for all eNOS polymorphisms. Likewise, there were no differences in haplotype frequencies among diabetic patients with or without diabetic retinopathy (p values > 0.05 for all comparisons).

CONCLUSION

Our findings do not support the hypothesis that the -786T/C, the VNTR intron 4 a/b and the 894G/T (Glu298Asp) polymorphisms in the eNOS gene play a role in the pathogenesis of diabetic retinopathy in type 2 diabetes.