Angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism, and diabetic retinopathy in subjects with IDDM and NIDDM

No Association of Angiotensin-Converting Enzyme Insertion/Deletion (ACE I/D) Gene Polymorphism in the Susceptibility to Diabetic Retinopathy in Type 2 Diabetes Mellitus Patients: An Updated Meta-Analysis

Diabetic retinopathy (DR) is a complex and multifactorial pathology encompassing environmental, metabolic, and polygenic influences. Among the genes possibly involved in the development and progression of DR, the Angiotensin I-converting enzyme (ACE) gene stands out, which presents an insertion (I) or deletion (D) polymorphism of a 287 bp Alu repetitive sequence in intron 16. Thus, this study aimed to perform a systematic review with meta-analysis to elucidate the relationship between the ACE gene (I/D) polymorphism (rs1799752) and the development and progression of DR in type 2 diabetic patients. PubMed/MEDLINE, Embase, Web of Science, and Scopus databases were systematically searched to retrieve articles that investigated the association between ACE gene (I/D) polymorphism in DR patients. Sixteen articles were included in the systematic review. The results describe no significant association between the polymorphism and DR risk (OR = 1.12; CI = 0.96-1.31; and p = 0.1359) for genotypic analysis by the dominant model (II vs. ID+DD). Moreover, we also observed no significant association between the D allele on the allele frequency analysis (I vs. D) and the DR risk (OR = 1.10; CI = 0.98-1.23; and p = 0.1182). Forest plot analysis revealed that the discrepancy between previous studies most likely arose from variations in their sample sizes. In conclusion, I/D polymorphism appears to be not involved in the susceptibility to and progression of the DR in type 2 diabetic patients.

Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy

Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.

Dietary Fat Intake Modulates Effects of a Frequent ACE Gene Variant on Glucose Tolerance with association to Type 2 Diabetes

The frequent ACE insertion/deletion polymorphism (I/D) is, albeit inconsistently, associated with impaired glucose tolerance and insulin resistance. We recently observed an enhanced upregulation of ACE by elevated fat intake in GG-carriers of the I/D-surrogate rs4343 variant and therefore investigated its potential nutrigenetic role in glucose metabolism. In this nutritional intervention study 46 healthy and non-obese twin pairs consumed recommended low fat diets for 6 weeks before they received a 6-week high fat (HF) diet under isocaloric conditions. Intravenous glucose tolerance tests were performed before and after 1 and 6 weeks of HF diet. While glucose tolerance did not differ between genotypes at baseline it significantly declined in GG-carriers after 6 weeks HF diet (p = 0.001) with higher 2 h glucose and insulin concentrations compared to AA/AG-carriers (p = 0.003 and p = 0.042). Furthermore, the gene-diet interaction was confirmed in the cross-sectional Metabolic Syndrome Berlin Potsdam study (p = 0.012), with the GG-genotypes being significantly associated with prevalent type 2 diabetes for participants with high dietary fat intake ≥37% (GG vs. AA/AG, OR 2.36 [1.02-5.49], p = 0.045). In conclusion, the association between the rs4343 variant and glucose tolerance is modulated by dietary fat intake. The ACE rs4343 variant is a novel nutrient-sensitive type 2 diabetes risk marker potentially applicable for nutrigenetic dietary counseling.

Association between the Angiotensin-Converting Enzyme (ACE) Genetic Polymorphism and Diabetic Retinopathy-A Meta-Analysis Comprising 10,168 Subjects

Aims-to address the inconclusive findings of the association of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism on risk of diabetic retinopathy (DR), a meta-analysis was conducted. Methods-we conducted a meta-analysis on 4252 DR cases and 5916 controls from 40 published studies by searching electronic databases and reference lists of relevant articles. A random-effects or fixed-effects model was used to estimate the overall and stratification effect sizes on ACE I/D polymorphism on the risk of DR. Results-we found a significant association between the ACE I/D polymorphism and the risk of DR for all genetic model (ID vs. II: OR = 1.14, 95% CI: 1.00-1.30; DD vs. II: OR = 1.38, 95% CI: 1.11-1.71; Allele contrast: OR = 1.17, 95% CI: 1.05-1.30; recessive model: OR = 1.24, 95% CI: 1.02-1.51 and dominant model: OR = 1.21, 95% CI: 1.06-1.38, respectively). In stratified analysis by ethnicity and DM type, we further found that the Asian group with T2DM showed a significant association for all genetic models (ID vs. II: OR = 1.14, 95% CI: 1.01-1.30; DD vs. II: OR = 1.54, 95% CI: 1.14-2.08; Allele contrast: OR = 1.26, 95% CI: 1.09-1.47; recessive model: OR = 1.42, 95% CI: 1.07-1.88 and dominant model: OR = 1.26, 95% CI: 1.07-1.49, respectively). Conclusion-our study suggested that the ACE I/D polymorphism may contribute to DR development, especially in the Asian group with type 2 diabetes mellitus (T2DM). Prospective and more genome-wide association studies (GWAS) are needed to clarify the real role of the ACE gene in determining susceptibility to DR.

Role of ACE and PAI-1 Polymorphisms in the Development and Progression of Diabetic Retinopathy

In the present study we determined the association of angiotensin converting enzyme (ACE) and plasminogen activator inhibitor-1 (PAI-1) gene polymorphisms with diabetic retinopathy (DR) and its sub-clinical classes in Pakistani type 2 diabetic patients. A total of 353 diabetic subjects including 160 DR and 193 diabetic non retinopathy (DNR) as well as 198 healthy controls were genotyped by allele specific polymerase chain reaction (PCR) for ACE Insertion/Deletion (ID) polymorphism, rs4646994 in intron 16 and PAI-1 4G/5G (deletion/insertion) polymorphism, rs1799768 in promoter region of the gene. To statistically assess the genotype-phenotype association, multivariate logistic regression analysis was applied to the genotype data of DR, DNR and control individuals as well as the subtypes of DR. The ACE genotype ID was found to be significantly associated with DR (p = 0.009, odds ratio (OR) 1.870 [95% confidence interval (CI) = 1.04–3.36]) and its sub-clinical class non-proliferative DR (NPDR) (p = 0.006, OR 2.250 [95% CI = 1.098–4.620]), while PAI polymorphism did not show any association with DR in the current cohort. In conclusion in Pakistani population the ACE ID polymorphism was observed to be significantly associated with DR and NPDR, but not with the severe form of the disease i.e. proliferative DR (PDR).

Association Analysis of Polymorphisms in Genes Related to Oxidative Stress in South Indian Type 2 Diabetic Patients with Retinopathy

BACKGROUND

Diabetic Retinopathy (DR) is one of the most common microvascular complications of type 2 diabetes mellitus (T2DM) and is polygenic with a multitude of genes contributing to disease susceptibility. The present study aimed at exploring the association between DR and seven polymorphisms in oxidative stress-related genes, i.e. ACE, eNOS, p22phox subunit of NAD(P)H oxidase, PARP-1 and XRCC1 in South Indian T2DM subjects.

MATERIALS AND METHODS

The study included 149 T2DM subjects with DR (diagnosed through funduscopic examination) and 162 T2DM patients with no evidence of DR. The selected polymorphisms were genotyped by polymerase chain reaction (PCR) and Taqman allele discrimination assay.

RESULTS

There was no significant difference in the genotype and allele distribution of ACE ins/del, eNOS-786T>C, 894G>T, 4a4b and p22phox 242C>T polymorphisms between T2DM groups with and without DR. Contrastingly, there appeared to be a significant association of PARP-1 Val762Ala and XRCC1 Arg399Gln polymorphisms with DR, wherein 762Ala allele seemed to confer significant protection against DR (p = 0.01; OR = 0.51 [0.3-0.86]), while the presence of 399Gln allele was associated with an enhanced risk for DR (p = 0.02; OR = 1.52 [1.07-2.15]). Multiple logistic regression analysis revealed a significant and independent association of Val762Ala and Arg399Gln polymorphisms and other putative risk factors with DR in T2DM individuals.

CONCLUSIONS

The polymorphisms in the DNA repair genes PARP-1 and XRCC1 tended to associate significantly with DR. While Val762Ala polymorphism was associated with reduced susceptibility to DR, the Arg399Gln polymorphism contributed an elevated to risk for DR in South-Indian T2DM individuals.

ACE I/D and MTHFR C677T polymorphisms are significantly associated with type 2 diabetes in Arab ethnicity: a meta-analysis

In this meta-analysis study, SNPs were investigated for their association with type 2 diabetes (T2D) in both Arab and Caucasian ethnicities. A total of 55 SNPs were analyzed, of which 11 fulfilled the selection criteria, and were used for analysis. It was found that TCF7L2 rs7903146 was significantly associated with a pooled OR of 1.155 (95%C.I.=1.059-1.259), p<0.0001 and I(2)=78.30% among the Arab population, whereas among Caucasians, the pooled OR was 1.45 (95%C.I.=1.386-1.516), p<0.0001 and I(2)=77.20%. KCNJ11 rs5219 was significantly associated in both the populations with a pooled OR of 1.176(1.092-1.268), p<0.0001 and I(2)=32.40% in Caucasians and a pooled OR of 1.28(1.111-1.475), p=0.001 among Arabs. The ACE I/D polymorphism was found to be significantly associated with a pooled OR of 1.992 (95%C.I.=1.774-2.236), p<0.0001 and I(2)=83.20% among the Arab population, whereas among Caucasians, the pooled OR was 1.078 (95%C.I.=0.993-1.17), p=0.073 and I(2)=0%. Similarly, MTHFR C677T polymorphism was also found to be significantly associated among Arabs with a pooled OR of 1.924 (95%C.I.=1.606-2.304), p<0.0001 and I(2)=27.20%, whereas among Caucasians, the pooled OR was 0.986 (95%C.I.=0.868-1.122), p=0.835 and I(2)=0%. Meanwhile PPARG-2 Pro12Ala, CDKN2A/2B rs10811661, IGF2BP2 rs4402960, HHEX rs7923837, CDKAL1 rs7754840, EXT2 rs1113132 and SLC30A8 rs13266634 were found to have no significant association with T2D among Arabs. In conclusion, it seems from this study that both Arabs and Caucasians have different SNPs associated with T2D. Moreover, this study sheds light on the profound necessity for further investigations addressing the question of the genetic components of T2D in Arabs.

Association of angiotensin-converting enzyme gene 2350 G/A polymorphism with diabetic retinopathy in Chinese Han population

The angiotensin-converting enzyme (ACE) gene is one of the most studied candidate genes related to diabetic retinopathy (DR). ACE 2350 G/A polymorphism (rs4343) is known among the polymorphisms of this gene to have the most significant effect on plasma ACE concentrations. The aim of the present study was to investigate the relationship between 2350 G/A polymorphism of ACE gene and the susceptibility of DR in Chinese Han population. A case-control study for 145 type 2 diabetes mellitus (DM) patients, including 63 type 2 DM without DR (NDR) and 82 type 2 DM with DR (DR), and 90 subjects of age, gender matched normal controls (NC group) was performed. ACE 2350 G/A genotypes were identified by polymerase chain reaction and restriction digestion in all study participants. The distribution of the ACE 2350 G/A genotypes (GG, GA, and AA) was 35.56, 45.55, and 18.89 % in the NC group, 28.57, 46.03, and 25.40 % in the NDR group, and 15.85, 46.34, and 37.81 % in the DR group, respectively. There were no significant differences in either genotype frequency distribution (P = 0.5266) or allele frequency distribution (P = 0.2425) between the NC group and NDR group. However, the distribution of genotype frequency (P = 0.0026) and allele frequency (P = 0.0003) in the DR group showed a significant difference when compared to that of NC group (P = 0.0075). Moreover, there was statistical difference in allele frequency distribution (P = 0.0328) between the DR group and the NDR group. No statistical differences were observed between ACE 2350 G/A polymorphism and the diabetes duration or types of DR. Results obtained in this study indicate that ACE 2350 G/A polymorphism is associated with DR in Han Chinese patients with type 2 DM.

Angiotensin-converting enzyme gene polymorphism is associated with proliferative diabetic retinopathy: a meta-analysis

The association of angiotensin-converting enzyme (ACE) gene polymorphism with diabetic retinopathy (DR) was investigated in many studies with conflicting results. To shed light on these inconclusive findings, a meta-analysis of all available studies relating I (insert)/D (delete) polymorphism to the risk of developing DR was conducted. This meta-analysis included genotype data on 2,342 cases with DR and 2,048 controls free of DR. Summary odds ratios were estimated. Potential sources of heterogeneity and bias were explored. Overall, in allelic genetic model, heterogeneity between studies was nonsignificant (P = 0.12). No publication bias was observed in the regression asymmetry test (τ = 0.84, P = 0.41). There was no significant association between this variant and DR. In additional analysis, the association of I/D variant with retinopathy was nonsignificant both in patients with type 1 diabetes (T1D) (1.01 [95% CI: 0.79-1.29]) and in patients with type 2 diabetes (T2D) (1.12 [95% CI: 0.93-1.35]). Significant association was not also observed between I/D variant and the background diabetic retinopathy (BDR). For the I/D polymorphism and its relationship to proliferative diabetic retinopathy (PDR), the dominant model showed nonsignificant heterogeneity among studies (P = 0.52; I (2) = 0%), and the fixed estimate pooled odd ratio (OR) JOP was significant, at 1.37 [95% CI: 1.02-1.84]. No association was observed between ACE I/D variant and DR, irrespective of the diabetic type. There was moderate evidence of its relationship to PDR, while its relationship to BDR was not found. Studies exploring the association between ACE I/D polymorphism and BDR or PDR may help us better understand the genetics of DR.

The relationship between ACE gene insertion/deletion polymorphism and diabetic retinopathy in Iranian patients with type 2 diabetes

BACKGROUND

The role of genetic factors in diabetic retinopathy (DR) is unclear. We investigated the relationship between DR and an insertion/deletion polymorphism in the angiotensin-converting enzyme (ACE) gene in Iranian patients with type 2 diabetes without overt nephropathy.

METHODS

A total of 178 consecutive type 2 diabetic patients with DR (Group A) and 206 type 2 diabetic patients without DR (Group B) were studied. The following variables were determined: age, sex, body mass index, diabetes duration, medications used, history of coronary artery disease and its complications, blood pressure (systolic and diastolic), fasting plasma glucose, hemoglobin A1c, total cholesterol, low- and high-density lipoproteins, triglycerides, plasma creatinine, and 24-h urine albumin excretion.

RESULTS

The groups were statistically similar in all variables except diabetes duration (P = 0.037), ACE activity (P < 0.001), and ACE genotype (P = 0.008). The DD genotype was significantly more common in Group A (32.6% versus 19.2% in Group B; P = 0.009). In multivariate regression analysis, the ID genotype (compared to the II genotype) was an independent predictor of DR (OR = 1.831, 95% CI = 1.074-3.124; P = 0.026).

CONCLUSIONS

The D allele of the ACE gene is independently associated with DR in Iranian type 2 diabetic patients.

Angiotensin-converting enzyme gene polymorphism is associated with type 2 diabetes: a meta-analysis

The association of angiotensin-converting enzyme gene polymorphism with type 2 diabetes was investigated in many studies with conflicting results. To clarify this conflict, we performed a meta-analysis on recent previous reports on ACE gene polymorphism and its correlation to type 2 diabetes. A total of 15,166 subjects from 24 studies were included in this meta-analysis. Summary odds ratios (ORs) were estimated. Potential sources of heterogeneity and bias were explored. The D variant was associated with a 14% increased risk of T2D relative to the I variant (OR 1.14; 95% CI: 1.04-1.24). In subgroup analysis, Caucasian and East Asians showed significant association. No association was found in the Turkish groups. No publication bias was observed in this meta-analysis by using the Egger method (tau = 1.63, P = 0.12), as well as the Begg's test (z = 1.66, P = 0.10). Cumulative meta-analysis for the allelic contrast showed a trend of association as information accumulated. These data suggested that the variant of ACE I/D had a moderate positive association with type 2 diabetes.

The relationship between angiotensin-converting enzyme insertion/deletion polymorphism and proliferative retinopathy in type 2 diabetes

A total of 136 type 2 diabetic patients with nonproliferative and 94 patients with proliferative diabetic retinopathy (PDR) without nephropathy were studied. The DD genotype of the angiotensin-converting enzyme polymorphism was more common in the PDR group (P<0.001). In multivariate regression, the association remained significant (OR=3.516).

Association of manganese superoxide dismutase gene polymorphism (V16A) with diabetic macular edema in Korean type 2 diabetic patients

This study was designed to investigate whether V16A polymorphism of the manganese superoxide dismutase (Mn-SOD) gene is associated with the development of type 2 diabetes mellitus and with progression of diabetic retinopathy (DR) and diabetic macular edema (DME). We simultaneously analyzed insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene in the 16th intron to avoid its confounding effect. A total of 192 nondiabetic subjects and 304 type 2 diabetic patients were included in the study. Diabetic retinopathy was classified as nonretinopathy, nonproliferative retinopathy, and proliferative retinopathy. Diabetic macular edema was defined as thickening of the retina and/or hard exudates within a 1-disk diameter of the center of the macula. Diabetic macular edema was further classified into focal, diffuse, and ischemic types. The A allele frequency of the Mn-SOD gene was not different between nondiabetic and type 2 diabetic subjects, between the normotensive and hypertensive groups, between the DR (-) and DR (+) groups, and among the stages of DR. In the DR (+) group, the DME (+) group had a lower A allele frequency than that of the DME (-) group. In the DME (+) group, focal, diffuse, and ischemic types were found in 8, 23, and 6 patients, respectively. The A allele frequency of each type was 0.188, 0.109, and 0.0. The D allele frequency of the angiotensin-converting enzyme gene did not differ in any of the comparisons. Clinical and laboratory parameters of the A allele carriers were not different from those of the noncarriers except for the prevalence of hypertension and DME. Hypertension, diabetic duration, and insulin therapy were related to DR. The A allele, hypertension, and insulin therapy were associated with DME. In conclusion, our results suggest that V16A polymorphism of the Mn-SOD gene is not related to the development of diabetes and progression of DR, but is associated with DME in Korean type 2 diabetic patients.

Frequency of angiotensin-converting enzyme gene polymorphism in Turkish type 2 diabetic patients

We aimed to investigate the angiotensin-converting enzyme (ACE) gene polymorphism, ACE activity and their associations with diabetic complications in Turkish patients with type 2 diabetes mellitus. A total of 143 patients and 133 controls were screened for ACE gene I/D polymorphism by using polymerase chain reaction. Serum ACE activities were determined spectrophotometrically. There was no significant difference in the distribution of ACE I/D genotypes between patients and controls. The patients with DD genotype had a higher ACE activity than those with ID and II. Hypertensive diabetic patients with DD genotype had higher ACE activities than those with ID and II. There was no significant difference in the distribution of ACE I/D genotypes between patients with and without nephropathy, retinopathy and hypertension except for patients with and without neuropathy. In patients with DD genotype, creatinine clearance correlated with duration of diabetes. The grade of retinopathy was correlated with duration of diabetes in DD and ID genotypes. The highest ACE activity was measured in hypertensive diabetics with DD genotype. ID genotype was suggested to be a risk factor and II was suggested to be protective for diabetic neuropathy. The DD and ID genotypes might be a predictor for the development of retinopathy in relation to duration of diabetes.

Relation between polymorphisms G1704T and G82S of rage gene and diabetic retinopathy in Japanese type 2 diabetic patients

OBJECTIVE

To clarify whether polymorphisms G1704T and G82S of the rage gene were related to diabetic retinopathy, we performed a case-control study in Japanese type 2 diabetic patients.

PATIENTS AND METHODS

Two hundred and sixty-eight patients with type 2 diabetes were examined for polymorphisms G1704T and G82S of the RAGE gene. The genotypes of G1704T and G82S of the RAGE gene were determined with a fluorescent allele-specific DNA primer assay system. Diabetic retinopathy (DR) was diagnosed in a masked manner by independent ophthalmologists using fundus photographs and was classified as non-diabetic retinopathy (NDR), non-proliferative retinopathy (NPDR), and proliferative retinopathy (PDR).

RESULTS

The T allele frequency of G1704T and S allele frequency of G82S in patients with DR did not significantly differ from those without retinopathy. There were no differences among the genotypes of G1704T and G82S of the RAGE gene regarding age, duration of diabetes, BMI, HbA(1c), blood pressure, and lipids levels.

CONCLUSION

These data suggest that polymorphisms G1704T and G82S of the RAGE gene are not related to DR in Japanese type 2 diabetic patients.

HLA-DRB1, -DQA1, and -DQB1 subtypes or ACE gene polymorphisms do not seem to be risk markers for severe retinopathy in younger Type 1 diabetic patients

The aim of this study was to test the hypothesis that HLA-DRB1, -DQA1, and -DQB1 subgroups or angiotensin-converting enzyme (ACE) gene polymorphisms are associated with severe retinopathy in younger Type 1 diabetic patients. Twenty-four Type 1 diabetic patients who had received panretinal photocoagulation for severe nonproliferative or proliferative diabetic retinopathy were compared with 24 Type 1 diabetic patients (participating in a photographic screening program with regular fundus examinations) with no or minimal retinopathy, matched for age at onset and duration of diabetes. The HLA-DRB1-DQA1-B1 haplotype 04-03-0302 represented 22/48 (46%) in the severe and 21/48 (44%) in the no/minimal retinopathy group, respectively (n.s.). The most common genotype, 03-0501-0201/04-03-0302, occurred in 8/24 (33%) with severe and 10/24 (42%) with no/minimal retinopathy, respectively (n.s.). There were no statistical differences between patients with severe and no/minimal retinopathy whether DRB1, DQA1, or DQB1 alleles, haplotypes, or genotypes were analysed. The ACE gene polymorphism was almost identical between patients with severe and no/minimal retinopathy, and serum ACE levels did not differ. Thus, in the present study on a small group with carefully characterised diabetic retinopathy phenotypes, there was no indication that HLA-DRB1, -DQA1, and -DQB1 subtypes or ACE gene polymorphisms were associated with severe retinopathy in younger Type 1 diabetic patients.

Molecular genetics of microvascular disease in diabetic retinopathy

Diabetic retinopathy is a sight-threatening complication of the retinal microvasculature. While important environmental factors have been clearly identified as influencing its development, increasing evidence suggests that diabetic retinopathy has a genetic component. A variety of studies have explored associations between candidate genes and frequency and severity of retinopathy. Overall, this review has found that the majority of candidate genes studied exhibit weak or no association with retinopathy status, and where associations have been detected these results have not been replicated in multiple populations. This may reflect inaccurate case definition, small subject numbers and possibly inadequate markers for genetic studies.

Is angiotensin I-converting enzyme a "master" disease gene?

Clustering of diseases has been appreciated by health insurers and epidemiologists for some time. Co-morbidity suggests shared pathways of disease. It is by now well agreed that common diseases have a strong genetic component. Here we present evidence that the angiotensin I-converting enzyme (ACE) deletion/deletion (D/D) genotype is associated with a large number of common adult diseases, including cardiovascular disease, cancer, and psychiatric disease. Since the ACE D/D genotype has been shown to be associated with increased levels of tissue ACE expression at the protein level, these data suggest that overactivity of ACE may be involved in the pathogenesis of common diseases, as well as the utility of effective ACE inhibition in their treatment and, perhaps, prevention.

Angiotensin-converting enzyme gene polymorphism and microvascular complications in Turkish type 2 diabetic patients

The aim of this study was to investigate whether an association exists between the angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism and microvascular complications of type 2 diabetes mellitus in Turkish patients. A total of 239 type 2 diabetic patients and 138 sex and age matched control subjects were included into the study. The I/D polymorphism was determined by polymerase chain reaction (PCR). Nephropathy status was determined according to urinary albumin/creatinine ratio (microg/mg) (<30 normoalbuminuria, 30-300 microalbuminuria, >300 macroalbuminuria) and retinopathy was evaluated by fundoscopic examination and by flourescein fundus angiography. The distribution of ACE I/D polymorphism and allele frequencies in diabetic patients were not significantly different from controls, DD genotype 32.2 versus 37.2%; ID genotype 50.6 versus 47.1%; and II 17.2 versus 15.2%; D allele 57.5 versus 61.2%; I allele 42.5 versus 38.8%. Genotype distribution between normo-, micro- and macroalbuminuric patients did not differ significantly (DD:ID:II (%), normoalbuminuria, 35:46:19; microalbuminuria, 28:55:17; macroalbuminuria, 31:55:14). There was also no difference in genotype distribution between patients with and without retinopathy (DD:ID:II (%), retinopathy positive, 32:51:17; retinopathy negative, 33:49:18). In conclusion, the ACE I/D polymorphism does not seem to be associated with diabetic nephropathy and retinopathy in Turkish type 2 diabetic patients.

Effects of novel polymorphisms in the RAGE gene on transcriptional regulation and their association with diabetic retinopathy

Interactions between advanced glycation end products (AGEs) and the receptor for AGE (RAGE) are implicated in the vascular complications in diabetes. We have identified eight novel polymorphisms, of which the -1420 (GGT)n, -1393 G/T, -1390 G/T, and -1202 G/A were in the overlapping PBX2 3' untranslated region (UTR), and the -429 T/C (66.5% TT, 33.5% TC/CC), -407 to -345 deletion (99% I, 1% I/D, 0% D), -374 T/A (66.4% TT, 33.6% TA/AA), and +20 T/A were in the RAGE promoter. To evaluate the effects on transcriptional activity, we measured chloramphenicol acetyl transferase (CAT) reporter gene expression, driven by variants of the -738 to +49 RAGE gene fragment containing the four polymorphisms identified close to the transcriptional start site. The -429 C, -374 A, and 63-bp deletion alleles resulted in a mean increase of CAT expression of twofold (P < 0.0001), threefold (P < 0.001), and fourfold (P < 0.05), respectively, with the -374 T and A alleles yielding highly differential binding of nuclear protein extract from both monocyte- and hepatocyte-derived cell lines. The prevalence of the functional polymorphisms were investigated in subjects with type 2 diabetes (106 with and 109 without retinopathy), with the -429 C allele showing an increase in the retinopathy group (P < 0.05). These data suggest that the polymorphisms involved in differences in RAGE gene regulation may influence the pathogenesis of diabetic vascular complications.

Genetic polymorphism of renin-angiotensin system is not associated with diabetic vascular complications in Japanese subjects with long-term insulin dependent diabetes mellitus

In a hospital cohort study, we examined whether or not ACE (Angiotensin-I converting enzyme) and AGT (Angiotensinogen) gene polymorphisms were associated with the development of nephropathy in long-term Japanese insulin-dependent diabetes mellitus (IDDM) patients with or without proliferative retinopathy, and whether or not the polymorphisms were associated with an arteriosclerotic family history in first degree relatives of the patients. A total of 201 patients with IDDM for more than 10 years and 159 patients with IDDM for more than 15 years were randomly selected in our hospital. All patients received uniform diabetes management and were divided into three groups, no nephropathy, incipient nephropathy and clinical nephropathy groups. There were no differences in clinical characteristics excluding urinary albumin to creatinine ratio and systolic blood pressure between the three groups. ACE I/D polymorphism was related to plasma ACE activity, but there were no associations between ACE I/D polymorphism and the development of diabetic nephropathy, nor was renal deterioration observed in patients with proliferative retinopathy even in those with a history of diabetes for more than 15 years. The AGT polymorphism did not have an additive effect on the association between ACE polymorphism and the development of diabetic nephropathy in patients with or without retinopathy. Development of diabetic nephropathy in the patients with or without proliferative retinopathy did not result in ACE or AGT polymorphisms. On the other hand, the ACE DD genotype was associated with a family history of ischemic heart disease in first degree relatives (X2 score = 9.04, P < 0.05). ACE and AGT gene polymorphisms may not play a role in the protective or accelerative effect against the development of diabetic nephropathy in the patients with or without proliferative retinopathy, but ACE gene polymorphism might be related to an arteriosclerotic family history in Japanese IDDM patients.

Angiotensin-converting enzyme gene and diabetes mellitus

AIMS

The association of the insertion/deletion polymorphism in the angiotensin-converting enzyme (ACE) gene with cardiovascular disease and diabetic nephropathy remains a controversial issue. This review aims to give an overview of the research to date assessing the impact of the ACE polymorphism in Type 1 and Type 2 diabetes mellitus (DM).

METHODS

A systematic review of the literature was performed in the databases of MEDLINE, PubMed and EMBASE for the key words 'diabetes mellitus', 'diabetic nephropathy', 'ACE polymorphism' and 'genotype' and relevant articles were considered.

RESULTS

A meta-analysis assessing the influence of the ACE polymorphism on disease susceptibility demonstrated significant odds ratios in individuals with the DD genotype for coronary heart disease, myocardial infarction and both diabetic and nondiabetic renal disease. No association was found for left ventricular hypertrophy or hypertension in nondiabetic subjects.

CONCLUSIONS

The ACE polymorphism appears to have a significant impact on the progression of diabetic nephropathy and may have therapeutic implications for identifying those individuals resistant to the effects of ACE inhibitors. It also appears to be indicative of an increased vascular risk in diabetic patients; however, larger prospective studies are required to clarify this situation.

Insertion/deletion polymorphism of the angiotensin I-converting enzyme gene in patients with hypertension, non-insulin-dependent diabetes mellitus, and coronary heart disease in Taiwan

An insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) gene has been identified that determines most of the plasma ACE activity genetically. Association of the D allele with insulin sensitivity and of the D/D genotype with coronary heart disease (CHD) has been reported in various ethnic populations. To study the role of this genetic polymorphism in patients with hypertension, non-insulin-dependent diabetes mellitus (NIDDM), and NIDDM with CHD in a Taiwanese population, we used a polymerase chain reaction (PCR)-based genotyping technique with an insertion-specific primer for confirmation of the I allele. One hundred ninety-seven unrelated normal controls, 67 subjects with hypertension, 107 subjects with NIDDM, and 70 subjects with NIDDM and CHD were recruited for this study; all were Han Chinese. Subjects without a history of diabetes were studied by a standard 75-g oral glucose tolerance test. Hypertension was diagnosed according to the Fifth Joint National Committee criteria, and CHD was confirmed by a history of acute myocardial infarction and coronary angiographic intervention. The frequency of the I allele of the ACE gene in the normal population was 64.2%, which was higher than reported in white populations. The prevalence of the I allele of the ACE gene was not significantly increased in subjects with hypertension (73.1%), NIDDM (62.1%), and NIDDM with CHD (65%) compared with healthy controls. The I allele of the ACE gene did not correlate with demographic and metabolic variables. I/D polymorphism of the ACE gene is not a marker for hypertension, NIDDM, or CHD in this Taiwanese population.