Aldose reductase gene polymorphisms and susceptibility to microvascular complications in Type 2 diabetes

Genetic variants of ALR (-106C → T /-12C → G) and serum PKC-δ are associated with peripheral neuropathy in Egyptian diabetic patients with impaired handwriting

Purpose

Diabetic peripheral neuropathy can injure the hand median nerve and cause extensive nerve damage. PKC and ALR are associated with progression of diabetic complications. We hypothesized a genetic association between the ALR polymorphisms (-106C → T/-12C → G) and elevated serum PKC-δ levels in diabetic neuropathy and its adverse effects on handwriting in Egyptian population.

Methods

One hundred DPN were compared with 100 DP and 100 healthy volunteers. ALR -106C → T/-12C → G variants were studied using the PCR-RFLP method. A routine set of standard laboratory markers was determined. Serum PKC-δ concentration was determined by ELISA. Logistic regression analysis and areas under the receiver characteristic curves (AUCs) were evaluated to investigate the predictors of diabetic neuropathy. Arabic handwriting was analyzed based on the recognition of functional features, word shape, and ascending/descending parts of letters.

Results

Individuals carrying ALR-106C → C and -12G → G had a significantly higher risk of developing diabetic neuropathy than individuals with -106C → T and -12C → G genotypes (P = 0.01, P = 0.02). Carriers of the (-106C → T) CC and (-12C → G) GG genotypes had significantly increased serum levels of PKC-δ, FBG, TC, and LDL-c. PKC- δ serum levels were significantly correlated with glycemic and lipid indicators (P < 0.001). PKC-δ is a significant predictor of diabetes with or without neuropathy at a cutoff value of 16.6, sensitivity was 89%, and specificity 100%. All DPN showed complete deterioration of handwriting after the onset of diabetic neuropathy.

Conclusion

The genetic variants ALR-106C → C / -12G → G and PKC-δ in serum may help in the detection and treatment of diabetic neuropathy in Egyptian population before writing performance is affected.

The A allele of the rs759853 single nucleotide polymorphism in the AKR1B1 gene confers risk for diabetic kidney disease in patients with type 2 diabetes from a Brazilian population

OBJECTIVE

The AKR1B1 gene encodes an enzyme that catalyzes the reduction of glucose into sorbitol. Chronic hyperglycemia in patients with diabetes mellitus (DM) leads to increased AKR1B1 affinity for glucose and, consequently, sorbitol accumulation. Elevated sorbitol increases oxidative stress, which is one of the main pathways related to chronic complications of diabetes, including diabetic kidney disease (DKD). Accordingly, some studies have suggested the rs759853 polymorphism in the AKR1B1 gene is associated with DKD; however, findings are still contradictory. The aim was to investigate the association of the rs759853 polymorphism in the AKR1B1 gene and DKD.

METHODS

The sample comprised 695 patients with type 2 DM (T2DM) and DKD (cases) and 310 patients with T2DM of more than 10 years' duration, but no DKD (controls). The polymorphism was genotyped by real-time PCR.

RESULTS

Allelic and genotype frequencies of this polymorphism did not differ significantly between groups. However, the A/A genotype was associated with risk for DKD after adjustment for gender, triglycerides, BMI, presence of hypertension and diabetic retinopathy, and duration of DM, under both recessive (P = 0.048) and additive (P = 0.037) inheritance models.

CONCLUSION

Our data suggest an association between the AKR1B1 rs759853A/A genotype and risk for DKD in Brazilians T2DM patients.

Recognition of DNA Methylation Molecular Features for Diagnosis and Prognosis in Gastric Cancer

Background: The management of gastric cancer (GC) still lacks tumor markers with high specificity and sensitivity. The goal of current research is to find effective diagnostic and prognostic markers and to clarify their related mechanisms.

Methods: In this study, we integrated GC DNA methylation data from publicly available datasets obtained from TCGA and GEO databases, and applied random forest and LASSO analysis methods to screen reliable differential methylation sites (DMSs) for GC diagnosis. We constructed a diagnostic model of GC by logistic analysis and conducted verification and clinical correlation analysis. We screened credible prognostic DMSs through univariate Cox and LASSO analyses and verified a prognostic model of GC by multivariate Cox analysis. Independent prognostic and biological function analyses were performed for the prognostic risk score. We performed TP53 correlation analysis, mutation and prognosis analysis on eleven-DNA methylation driver gene (DMG), and constructed a multifactor regulatory network of key genes.

Results: The five-DMS diagnostic model distinguished GC from normal samples, and diagnostic risk value was significantly correlated with grade and tumor location. The prediction accuracy of the eleven-DMS prognostic model was verified in both the training and validation datasets, indicating its certain potential for GC survival prediction. The survival rate of the high-risk group was significantly lower than that of the low-risk group. The prognostic risk score was an independent risk factor for the prognosis of GC, which was significantly correlated with N stage and tumor location, positively correlated with the VIM gene, and negatively correlated with the CDH1 gene. The expression of CHRNB2 decreased significantly in the TP53 mutation group of gastric cancer patients, and there were significant differences in CCDC69, RASSF2, CHRNB2, ARMC9, and RPN1 between the TP53 mutation group and the TP53 non-mutation group of gastric cancer patients. In addition, CEP290, UBXN8, KDM4A, RPN1 had high frequency mutations and the function of eleven-DMG mutation related genes in GC patients is widely enriched in multiple pathways.

Conclusion: Combined, the five-DMS diagnostic and eleven-DMS prognostic GC models are important tools for accurate and individualized treatment. The study provides direction for exploring potential markers of GC.

A New Symmetrical Thiazolidinedione Derivative: In Silico Design, Synthesis, and In Vivo Evaluation on a Streptozotocin-Induced Rat Model of Diabetes

By activating PPAR-γ, thiazolidinediones normalize glucose levels in animal models of type 2 diabetes and in patients with this pathology. The aim of the present study was to analyze 219 new derivatives in silico and select the best for synthesis, to be evaluated for acute oral toxicity in female rats and for control of diabetes-related parameters in a rat model of streptozotocin-induced diabetes. The best compound was chosen based on pharmacokinetic, pharmacodynamic, and toxicological parameters obtained in silico and binding orientation observed by docking simulations on PPAR-γ. Compound 1G was synthesized by a quick and easy Knoevenagel condensation. Acute oral toxicity was found at a dose greater than 2000 mg/Kg. Compound 1G apparently produces therapeutic effects similar to those of pioglitazone, decreasing glycaemia and triglyceride levels in diabetic animals, without liver damage. Moreover, it did not cause a significant weight gain and tended to reduce polydipsia and polyphagia, while diminishing systemic inflammation related to TNF-α and IL-6. It lowered the level of endogenous antioxidant molecules such as reduced glutathione and glutathione reductase. In conclusion, 1G may be a candidate for further testing as an euglycemic agent capable of preventing the complications of diabetes.

Aldose reductase (AC)n gene polymorphism in Iranian patients with type 2 diabetic microangiopathy; a case-control study

Aim

(AC)n promoter region of the aldose reductase (ALR) genes polymorphism has been associated with diabetic microvascular complications (MVCs). The aim of this study was to find the relationship between dinucleotide repeat (AC)n polymorphisms of the ALR gene and the occurrence of MVCs, such as diabetic retinopathy, neuropathy, and nephropathy in Iranian type 2 diabetic (T2D) patients.

Methods

This prospective case-control study was performed on T2D patients who were categorized into two groups based on the presence or absence of diabetic microangiopathy. All patients were provided informed consent. After extracting genomic DNA, the (AC)n of the ALR gene was determined using Polymerase chain reaction (PCR).

Results

Thirteen alleles of the (AC)n gene polymorphism were detected including Z + 16, Z + 14, Z + 8, Z + 6, Z + 4, Z + 2, Z, Z - 2, Z - 4, Z - 6, Z - 8, Z - 10, and Z - 12. The frequency of the Z - 4 allele was significantly higher in patients with retinopathy, nephropathy, and autonomic neuropathy compared with those with long-term uncomplicated diabetes (P < 0.001, P < 0.001, P = 0.031, respectively). After controlling for baseline risk factors, we found that the carrier of the Z - 4 allele of ALR (AC)n polymorphism had a higher risk of diabetic retinopathy and diabetic nephropathy (P < 0.001). The homozygosity for the Z - 4 allele was found to be associated with diabetic microangiopathy.

Conclusion

Our results showed that ALR (AC)n gene polymorphism in Iranian patients with type 2 diabetes independently, predispose retinal, renal and neural microvascular to diabetic complications.

Polymorphisms of Aldose Reductase (ALR2) Regulatory Gene are Risk Factors for Diabetic Retinopathy in Type-2 Diabetes Mellitus Patients in Bali, Indonesia

Aim

The study aimed to elucidate whether the polymorphisms of the aldose reductase regulatory gene were risk factors for Diabetic Retinopathy (DR) in type-2 diabetes mellitus (T2DM) patients in Bali.

Methods

This is a case-control study including 35 cases of T2DM patients with DR paired with 35 cases with non-DR as controls. PCR analysis and DNA-sequencing were carried out to detect the C(-106)T and C(-12)G polymorphisms at the regulatory region of Aldose Reductase (ALR2) gene. Genotype and allele distributions were analyzed by Chi-squared test and independent t-and Mann-Whitney U tests were used to analyze other data.

Results

Among all subjects in both groups, the baseline characteristics were homogenous except for systolic blood pressure, fasting blood glucose and 2-hours post-prandial blood glucose. This study found two polymorphisms, C(-104)T and C(-9)G, in the regulatory region of ALR2 gene. The result showed that the C(-104)T polymorphism was a risk factor for DR (OR=36; 95% CI = 4.43-292.85; p=0.001), but not the C(-9)G polymorphism (OR=1.28; 95% CI=0.48-3.38; p=0.621). Other findings in the study revealed that CC/CC haplotype is a protective factor for DR (OR=0.198; p=0.002), whereas CT/CC and CT/CG haplotypes as risk factors for DR with OR=15.58; p=0.002 and OR=2.29; p=0.005 respectively.

Conclusion

It can be concluded that C(-104)T polymorphism in the regulatory region of Aldose Reductase (ALR2) gene was the risk factor for DR among T2DM patients in Bali, Indonesia. However, small sample size, systolic blood pressure, fasting blood glucose and 2-hours post-prandial blood glucose could affect our finding.

Association of aldose reductase gene (AKR1B1) polymorphism with diabetic retinopathy

AIMS

Present study aimed to investigate the association of aldose reductase (AKR1B1) gene polymorphism (-106C>T; rs759853) with diabetic retinopathy (DR) in type 2 diabetes mellitus (T2DM) patients from north India.

METHODS

The present case-control association study recruited 926 subjects, including 487 DR patients and 439 individuals with confirmed T2DM as controls (CDR). AKR1B1 -106C>T polymorphism analysis in these 926 subjects was performed by polymerase chain reaction and direct DNA sequence analysis. Statistical analysis was performed using SPSS package.

RESULTS

Statistically significant differences were observed between the two analyzed groups in the age of onset of diabetes (p=0.000) and duration of diabetes (p=0.000). Genotype distribution of AKR1B1 -106C>T polymorphism differed significantly between DR and CDR groups (p=0.02), however, distribution of allele frequency did not differ significantly (p=0.19). Binary logistic regression analyses showed an association of homozygous recessive TT genotype with diabetic retinopathy (OR: 1.61%, 95% CI, 1.39-2.284, p<0.01) in comparison to wild type CC genotype.

CONCLUSIONS

These findings suggest a statistically significant association of AKR1B1 -106C>T polymorphism with retinopathy in North Indian patients. To our knowledge, this is the first report of association of -106C>T polymorphism in AKR1B1 in DR patients from India.

Identifying Common Genetic Risk Factors of Diabetic Neuropathies

Type 2 diabetes mellitus (T2DM) is a global public health problem of epidemic proportions, with 60-70% of affected individuals suffering from associated neurovascular complications that act on multiple organ systems. The most common and clinically significant neuropathies of T2DM include uremic neuropathy, peripheral neuropathy, and cardiac autonomic neuropathy. These conditions seriously impact an individual's quality of life and significantly increase the risk of morbidity and mortality. Although advances in gene sequencing technologies have identified several genetic variants that may regulate the development and progression of T2DM, little is known about whether or not the variants are involved in disease progression and how these genetic variants are associated with diabetic neuropathy specifically. Significant missing heritability data and complex disease etiologies remain to be explained. This article is the first to provide a review of the genetic risk variants implicated in the diabetic neuropathies and to highlight potential commonalities. We thereby aim to contribute to the creation of a genetic-metabolic model that will help to elucidate the cause of diabetic neuropathies, evaluate a patient's risk profile, and ultimately facilitate preventative and targeted treatment for the individual.

Oxidative stress-related genes in type 2 diabetes: association analysis and their clinical impact

Worldwide prevalence of diabetes mellitus motivates a number of association studies to be conducted throughout the world. Eleven polymorphisms from nine candidate genes in oxidative stress pathway have been analyzed in eastern Indian type 2 diabetic patients (n = 145) and healthy controls (n = 100). Different biochemical parameters were also analyzed for their association with the disease. Significant associations were observed for rs2070424 A>G SOD1 (OR 3.91, 95% CI 2.265-8.142, P < 0.001), rs854573 A>G PON1 (OR 3.415, 95% CI 2.116-5.512, P < 0.001), rs6954345 G>C PON2 (OR 3.208, 95% CI 2.071-4.969, P < 0.001), RAGE rs1800624 -374 T>A (OR 3.58, 95% CI 2.218-5.766, P < 0.001), and NOS3 -786 T>C (OR 3.75, 95% CI 2.225-6.666, P < 0.001). Haplotype containing two risk alleles of PON1 and PON2 genes was significantly associated with disease (OR 8.34, 95% CI 1.554-44.804, P < 0.002). Our results suggest that carriers of major and efficient alleles of oxidative stress genes are more likely to survive the comorbid complications and single copy of risk allele is sufficient for developing the disease.

Is rs759853 polymorphism in promoter of aldose reductase gene a risk factor for diabetic nephropathy? A meta-analysis

Background

So far, a number of case-control or cohort studies have been carried out to investigate the relationship between rs759853 polymorphism in the promoter of aldose reductase (AR) gene and the risk of diabetic nephropathy (DN). However, the results have generated considerable controversy. We performed this study to clarify the linkage between this gene mutation and the risk of DN.

Methods

A comprehensive literature search of electronic databases and a well-organized meta-analysis were conducted.

Results

Twelve comparisons and 4,735 individuals from nine published case-control or cohort studies were included finally. From none to large heterogeneity was observed, therefore, both fixed and random models were used. Significant differences were found between AR rs759853 polymorphism and susceptibility of DN from both type 1 and type 2 diabetes in all genetic models (allele contrast, OR = 1.37, CI (1.18, 1.59), P < 0.0001; additive model, OR = 1.78, CI (1.25, 2.53), P = 0.01; recessive model OR = 1.33 CI (1.08, 1.63), P = 0.008; dominant model, OR = 1.52, CI (1.26, 1.84), P < 0.0001; codominance model OR = 1.30 (1.15, 1.47), P < 0.0001). In stratified meta-analyses for type 2 diabetes by ethnicity, the significant relationship was found in allele contrast and dominant model in Caucasians, and in allele contrast and codominance model in Asians. However, data do not support the linkage between this gene mutation and the progression of DN. There was no significant publication bias.

Conclusions

The evidence currently available shows that the AR rs759853 polymorphism may correlate with the susceptibility of DN. However, data do not support the association between this DNA variation and the progression of DN.

Aldose reductase C-106T gene polymorphism in type 2 diabetics with microangiopathy in Iranian individuals

BACKGROUND

Aldose reductase (AR) is the rate-limiting enzyme in the glucose metabolism, which has been implicated in the pathogenesis of diabetic microvascular complications (MVCs). Frequent C-106T polymorphism in the promoter of the AR gene may change the expression of the gene.

AIMS

The aim of the following study is to study the association between AR C106T genotypes and diabetic MVCs in Iranian population.

MATERIALS AND METHODS

We included 206 type 2 diabetic patients categorized into two groups according to the presence or absence of diabetic microangiopathy. The cases of interest were diabetic neuropathy, retinopathy and nephropathy identified during clinical and or laboratory examination. In addition, 114 age- and sex-matched individuals were selected to serve as a control group. AR genotyping was done using an amplification gel electrophoresis.

RESULTS

The frequency of CC genotype was specifically higher in subjects with diabetic retinopathy as compared to those without it (53.2% vs. 38.1%, P = 0.030). Patients with diabetic microangiopathy in general; however, did not differ significantly between AR genotype groups.

CONCLUSION

The C-106T polymorphism in the AR gene is likely a risk factor for development of only retinal complication of diabetes microvascular in Iranian individuals.

Relationship between five GLUT1 gene single nucleotide polymorphisms and diabetic nephropathy: a systematic review and meta-analysis

So far, case-control studies on the association between glucose transporter 1 (GLUT1) gene single nucleotide polymorphisms (SNPs) and diabetic nephropathy (DN) have generated considerable controversy. To clarify the linkage of GLUT1 SNPs on the risk of DN, a systematic review and meta-analysis was performed. A comprehensive literature search of electronic databases was conducted to obtain relative studies. Nine case-control studies were included. Significant differences were found between XbaI SNP (rs841853) and increased risk of DN in all genetic models. Subgroup analyses for Caucasians population and DN from both type 1 and type 2 diabetes also revealed positive results. For Enh2-1 SNP (rs841847), Enh2-2 SNP (rs841848) and HaeIII SNP (rs1385129), obvious linkages were demonstrated in recessive model. However, analysis for the association between HpyCH4V SNP (rs710218) and the susceptibility of DN showed no significance. Likewise, negative outcome was also found in the assessment for the influence of XbaI or Enh2-2 SNP on the pathogenesis progress of DN. The evidence currently available shows that XbaI, Enh2 and HaeIII SNPs, but not HpyCH4V SNP, in GLUT1 gene may be genetic susceptibility to DN. However, data does not support the association between either XbaI or Enh2-2 SNP and the severity of DN.

Aldose reductase C-106T gene polymorphism is associated with diabetic retinopathy in Japanese patients with type 2 diabetes

It is likely that the C allele of the polymorphism at position -106 in the promoter of aldose reductase gene, which codes a rate-limiting enzyme of the polyol pathway, is a susceptibility allele for diabetic retinopathy in Japanese type 2 diabetic patients.

Association analysis of ADPRT1, AKR1B1, RAGE, GFPT2 and PAI-1 gene polymorphisms with chronic renal insufficiency among Asian Indians with type-2 diabetes

BACKGROUND

To determine association of nine single nucleotide polymorphisms (SNPs) in ADP ribosyltransferase-1 (ADPRT1), aldo-keto reductase family 1 member B1 (AKR1B1), receptor for advanced glycation end-products (RAGE), glutamine:fructose-6-phosphate amidotransferase-2 (GFPT2), and plasminogen activator inhibitor-1 (PAI-1) genes with chronic renal insufficiency (CRI) among Asian Indians with type 2 diabetes; and to identify epistatic interactionss between genes from the present study and those from renin-angiotensin-aldosterone system (RAAS), and chemokine-cytokine, dopaminergic and oxidative stress pathways (previously investigated using the same sample set).

METHODS

Type 2 diabetes subjects with CRI (serum creatinine > or =3.0 mg/dl) constituted the cases (n = 196), and ethnicity and age matched individuals with diabetes for a duration of > or = 10 years, normal renal functions and normoalbuminuria recruited as controls (n = 225). Allelic and genotypic constitution of 10 polymorphisms (SNPs) from five genes namely--ADPRT1, AKR1B1, RAGE, GFPT2 and PAI-1 with diabetic CRI was investigated. The genetic associations were evaluated by computation of odds ratio and 95% confidence interval. Multiple logistic regression analysis was carried out to correlate various clinical parameters with genotypes, and to study epistatic interactions between SNPs in different genes.

RESULTS

Single nucleotide polymorphisms -429 T>C in RAGE and rs7725 C>T SNP in 3' UTR in GFPT2 gene showed a trend towards association with diabetic CRI. Investigation using miRBase statistical tool revealed that rs7725 in GFPT2 was a perfect target for predicted miRNA (hsa miR-378) suggesting the presence of the variant 'T' allele may result in an upregulation of GFPT2 contributing to diabetic renal complication. Epistatic interaction between SNPs in transforming growth factor TGF-beta1 (investigated using the same sample set and reported elsewhere) and GFPT2 genotype was observed.

CONCLUSIONS

Association of SNPs in RAGE and GFPT2 suggest that the genes involved in modulation of oxidative pathway could be major contributor to diabetic chronic renal insufficiency. In addition, GFPT2 mediated overproduction of TGF-beta1 leading to endothelial expansion and thereby CRI seems likely, suggested by our observation of a significant interaction between GFPT2 with TGF-beta1 genes. Further, identification of predicted miRNA targets spanning the associated SNP in GFPT2 implicates the rs7725 SNP in transcriptional regulation of the gene, and suggests GFPT2 could be a relevant target for pharmacological intervention. Larger replication studies are needed to confirm these observations.

Cellular signaling and potential new treatment targets in diabetic retinopathy

Dysfunction and death of microvascular cells and imbalance between the production and the degradation of extracellular matrix (ECM) proteins are a characteristic feature of diabetic retinopathy (DR). Glucose-induced biochemical alterations in the vascular endothelial cells may activate a cascade of signaling pathways leading to increased production of ECM proteins and cellular dysfunction/death. Chronic diabetes leads to the activation of a number of signaling proteins including protein kinase C, protein kinase B, and mitogen-activated protein kinases. These signaling cascades are activated in response to hyperglycemia-induced oxidative stress, polyol pathway, and advanced glycation end product formation among others. The aberrant signaling pathways ultimately lead to activation of transcription factors such as nuclear factor-κB and activating protein-1. The activity of these transcription factors is also regulated by epigenetic mechanisms through transcriptional coactivator p300. These complex signaling pathways may be involved in glucose-induced alterations of endothelial cell phenotype leading to the production of increased ECM proteins and vasoactive effector molecules causing functional and structural changes in the microvasculature. Understanding of such mechanistic pathways will help to develop future adjuvant therapies for diabetic retinopathy.

Diabetic neuropathies: unanswered questions

Diabetic neuropathies are the most common types of neuropathies worldwide. Although there has been significant progress in the understanding of the clinical aspects of these conditions, many questions remain unanswered or difficult to answer in terms of causation, risk factors and genetic susceptibility, effective treatments and restoration of nerve functions, and pain management. The major handicap in studying diabetic neuropathies is the lack of a suitable animal model that addresses acute and chronic events leasing to diabetic neuropathy. Unfortunately and despite numerous drug trials, other than strict glycemic control, which is often difficult to maintain, there are no other treatments to slow the progression or delay the development of diabetic neuropathy. This article attempts to highlight a few unanswered or controversial questions regarding diabetic neuropathies.

Aldo-keto reductases and bioactivation/detoxication

Aldo-keto reductases (AKRs) are soluble NAD(P)(H) oxidoreductases that primarily reduce aldehydes and ketones to primary and secondary alcohols, respectively. The ten known human AKR enzymes can turnover a vast range of substrates, including drugs, carcinogens, and reactive aldehydes. They play central roles in the metabolism of these agents, and this can lead to either their bioactivation or detoxication. AKRs are Phase I drug metabolizing enzymes for a variety of carbonyl-containing drugs and are implicated in cancer chemotherapeutic drug resistance. They are involved in tobacco-carcinogenesis because they activate polycyclic aromatic trans-dihydrodiols to yield reactive and redox active o-quinones, but they also catalyze the detoxication of nicotine derived nitrosamino ketones. They also detoxify reactive aldehydes formed from exogenous toxicants, e.g., aflatoxin, endogenous toxicants, and those formed from the breakdown of lipid peroxides. AKRs are stress-regulated genes and play a central role in the cellular response to osmotic, electrophilic, and oxidative stress.

Aldose reductase gene is associated with diabetic macroangiopathy in Japanese Type 2 diabetic patients

AIMS

The aldose reductase (AR) gene, a rate-limiting enzyme of the polyol pathway, has been investigated as a candidate gene in determining susceptibility to diabetic microangiopathy. However, the association of the AR gene with diabetic macroangiopathy has not been investigated. Therefore, the present study was conducted to determine whether genetic variations of AR may determine susceptibility to diabetic macroangiopathy.

METHODS

There were 378 Type 2 diabetic patients enrolled in this study. A single nucleotide polymorphism in the promoter region (C-106T) was genotyped and the AR protein content of erythrocytes measured by ELISA.

RESULTS

There were no significant differences in genotypic or allelic distribution in patients with or without ischaemic heart diseases, but there was a significant increase in the frequency of the CT + TT genotype and T allele in patients with stroke (P = 0.019 and P = 0.012). The erythrocyte AR protein content was increased in patients with the CT and TT genotype compared with those with the CC genotype. After adjustment for age, duration of diabetes, body mass index, systolic blood pressure, HbA1c, and serum creatinine, triglycerides, and total cholesterol in multivariate logistic-regression models, the association between this AR genotype and stroke remained significant.

CONCLUSIONS

Our results suggest that the CT or TT genotype of the AR gene might be a genetic marker of susceptibility to stroke in Type 2 diabetic patients. This observation might contribute to the development of strategies for the prevention of stroke in Type 2 diabetic patients.

The -106CC genotype of the aldose reductase gene is associated with an increased risk of proliferative diabetic retinopathy in Caucasian-Brazilians with type 2 diabetes

Diabetic retinopathy is a sight-threatening chronic complication of diabetes mellitus and is the leading cause of acquired blindness in adults. The -106C>T polymorphism in the promoter region of the aldose reductase (AR) gene has been shown to be associated with the susceptibility to diabetic nephropathy in type 2 diabetes, but the findings regarding the occurrence of diabetic retinopathy are conflicting. In this case-control study, we investigated whether the -106C>T polymorphism in the AR gene is involved in the development and progression of diabetic retinopathy in 579 Brazilians with type 2 diabetes (424 Caucasian- and 155 African-Brazilians). Patients underwent a clinical and laboratory evaluation consisting of a questionnaire, physical examination, assessment of diabetic complications and laboratory tests. Genotype analysis was performed using the polymerase chain reaction followed by digestion with restriction enzyme. Logistic regression analysis was used to control for independent risk factors associated with diabetic retinopathy. There were no differences in either genotype or allele frequencies for the -106C>T polymorphism between type 2 diabetic patients with or without diabetic retinopathy, in both ethnic groups. However, the CC genotype was associated with an increased risk of having proliferative diabetic retinopathy in Caucasian-Brazilians with type 2 diabetes (odds ratio (OR)=2.04; 95% confidence interval (CI)=1.21-3.45; P=0.007), independently of other risk factors associated with this complication. Thus, our results show that the -106CC genotype (-106C>T polymorphism) in the AR gene is related to the progression of diabetic retinopathy in Caucasian-Brazilians with type 2 diabetes.

Genetics of diabetic retinopathy

Diabetes is rapidly increasing in frequency with an attendant toll of complications, including diabetic retinopathy. Although the underlying mechanisms remain elusive, genetic susceptibility is key to both types 1 and 2 diabetes and is increasingly recognized for its contribution to diabetic complications. In this article we review the evidence connecting genetic susceptibility to diabetic retinopathy. Elucidating the susceptibility genes and pathways should permit strategies to slow and reverse the troubling trends for the population, families, and individuals.

Vascular endothelial dysfunction in diabetic cardiomyopathy: pathogenesis and potential treatment targets

Cardiovascular complications account for significant morbidity and mortality in the diabetic population. Diabetic cardiomyopathy, a prominent cardiovascular complication, has been recognized as a microvascular disease that may lead to heart failure. Pathogenesis of diabetic cardiomyopathy involves vascular endothelial cell dysfunction, as well as myocyte necrosis. Clinical trials have identified hyperglycemia as the key determinant in the development of chronic diabetic complications. Sustained hyperglycemia induces several biochemical changes including increased non-enzymatic glycation, sorbitol-myoinositol-mediated changes, redox potential alterations, and protein kinase C (PKC) activation, all of which have been implicated in diabetic cardiomyopathy. Other contributing metabolic abnormalities may include defective glucose transport, increased myocyte fatty acid uptake, and dysmetabolism. These biochemical changes manifest as hemodynamic alterations and structural changes that include capillary basement membrane (BM) thickening, interstitial fibrosis, and myocyte hypertrophy and necrosis. Diabetes-mediated biochemical anomalies show cross-interaction and complex interplay culminating in the activation of several intracellular signaling molecules. Studies in both animal and human diabetes have shown alteration of several factors including vasoactive molecules that may be instrumental in mediating structural and functional deficits at both the early and the late stages of the disease. In this review, we will highlight some of the important vascular changes leading to diabetic cardiomyopathy and discuss the emerging potential therapeutic interventions.