Association study of G1704T and G82S polymorphisms of RAGE gene for microalbuminuria in Japanese type 2 diabetic patients

To clarify whether polymorphisms G1704T and G82S of the RAGE gene were related to microalbuminuria, we performed a case-control study in Japanese type 2 diabetic patients. Polymorphisms G1704T and G82S of the RAGE gene were examined with genomic DNA obtained from 116 type 2 diabetic patients with microalbuminuria (urinary albumin/creatinine ratio between 30 and 300 mg/g of creatinine) (microalbuminuria group), and 232 patients with normoalbuminuria (urinary albumin/creatinine ratio <30 mg/g of creatinine) (normoalbuminuria group). The genotype distribution and T allele frequency of G1704T (9.9%) and S allele frequency of G82S (14.2%) in the microalbuminuria group did not significantly differ from those (T allele frequency, 8.4%; S allele frequency, 12.3%) in the normoalbuminuria group. There were no differences among the genotypes of G1704T and G82S of the RAGE gene regarding age, duration of diabetes, body mass index, glycosylated hemoglobin (HbA1c), blood pressure, and serum lipid levels. These data suggest that G1704T and G82S polymorphisms of the RAGE gene are not related to microalbuminuria in Japanese type 2 diabetic patients.     

糖基化终产物受体基因G1704T多态性与糖尿病肾病相关性的研究

采用Taqman PCR法探讨糖基化终产物受体（RAGE）基因G1704T多态性与糖尿病肾病的相关性。结果发现RAGE基因1704T等位基因频率在糖尿病肾病中显著增高（P〈0．05），由此推测RAGE基因1704T等位基因可能是糖尿病肾病发生的危险因素。     

Association of Gly82Ser polymorphism in the RAGE gene with diabetic retinopathy in type II diabetic Asian Indian patients

Aim/hypothesis: The binding of advanced glycation end products (AGE) to the receptor induces cellular oxidative stress and vascular dysfunction and this is implicated in the pathogenesis of diabetic retinopathy (DR). This study aims to investigate the frequency of Gly82Ser polymorphism in exon 3 of the receptor for AGE (RAGE) gene and its association with DR in Asian Indian patients who have type II diabetes. Methods: 200 Asian Indian patients with at least 15-year duration of type II diabetes were identified. This group included (1) 100 patients with retinopathy (DR) and (2) 100 patients without retinopathy (DNR). Fifty unrelated healthy controls (CT) were also included in the study. Genotype frequencies of Gly82Ser polymorphism were studied by polymerase chain reaction (PCR) amplification and restriction fragment length polymorphism analysis using AluI enzyme. Later, the nucleotide change was confirmed by DNA sequencing. Results: The frequency of the Ser82 allele was significantly higher, 18% in the DNR group compared to 7% in the DR group (P=.03). The same genotype was 2% in the CT group. Conclusion/interpretation: Our result suggests that Ser82 allele in the receptor for AGE gene is a low-risk allele for developing DR in Asian Indian patients who have type II diabetes.     

No association between MTHFR gene polymorphism and diabetic nephropathy in Japanese type II diabetic patients with proliferative diabetic retinopathy

The development of diabetic nephropathy shows marked variation among individuals. Not only hyperglycemia, but also genetic factors may contribute to the development of diabetic nephropathy. Methylenetetrahydrofolate reductase (MTHFR) is involved in remethylation of homocysteine to methionine. Decreased activity of MTHFR which can result in hyperhomocysteinemia may lead to cerebrovascular disease and coronary artery disease. Recently, a common C to T mutation at nucleotide position 677 of the MTHFR gene (MTHFR677C>T) has been reported to be correlated with hyperhomocysteinemia and the severity of coronary artery disease as macroangiopathy. In the present study, we recruited 173 of Japanese type II diabetic patients with proliferative diabetic retinopathy who would be exposed to long-term hyperglycemia, and examined the contribution of the MTHFR gene polymorphism to the development of diabetic nephropathy as microangiopathy. The frequency of the mutated allele was 43.3% in patients with nephropathy (n = 105) versus 41.9% in those without nephropathy (n = 68). The genotype frequencies were +/+, 16.2%; +/−, 54.3%; −/−, 29.5% in patients with nephropathy versus +/+, 13.2%; +/−, 57.4%; −/−, 29.4% in those without nephropathy (+ indicates the presence of the mutation). The MTHFR genotype and allele frequencies were not significantly different between patients with and without nephropathy. Therefore, we conclude that the MTHFR gene polymorphism is not associated with the development of diabetic nephropathy in Japanese type II diabetic patients.     

Polymorphisms 1704G/T and 2184A/G in the RAGE gene are associated with antioxidant status

The formation of advanced glycation end products (AGEs) and oxidative stress are supposed to play an important role in the development of diabetic late complications. AGEs can bind to several binding sites including receptor of advanced glycation end products (RAGE). AGE-RAGE interaction results in free radical generation. The aim of the present study was to investigate the impact of previously described polymorphisms in the RAGE gene (G82S, 1704G/T, 2184A/G, and 2245G/A) on the glycoxidation status in non-insulin-dependent diabetes mellitus (NIDDM). A total of 371 unrelated caucasian subjects were enrolled in the study. The NIDDM group consisted of 202 subjects, and the presence of late diabetic complications in 5 particular localizations was expressed as an index (I(compl)). The nondiabetic group included 169 subjects. Glycated hemoglobin (HbA(1c)), glycated stratum corneum proteins (Amadori, AGE), total carotenoids, alpha- and beta -carotene, gamma-tocopherol, lutein, lycopene, and alpha-tocopherol were measured in each subject. Statistically significant differences in allele frequencies between the NIDDM and the nondiabetic groups were observed for the G82S and 2245G/A polymorphisms (P =.047 and .032, respectively). HbA(1c), Amadori, and AGE did not reveal any significant association with any of the polymorphisms analyzed. However, significant differences between subjects bearing "wild-type majority" genotypes 1704GG+2184AA and subjects with "mutated" genotypes were found for total carotenoids (P =.001), alpha-carotene (P =.046), beta-carotene (P =.028), lutein (P =.001), lycopene (P =.006), and alpha-tocopherol (P =.047). I(compl) significantly correlated with the plasma levels of all antioxidants (all P <.01), while no correlation of I(compl) with glycation variables was observed. The newly identified intron polymorphisms in the RAGE gene were proved to be associated with the antioxidant status in NIDDM subjects. The extent of diabetic vascular disease is related to the plasma levels of antioxidants.     

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.     

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 29 of the translated sequence of transforming growth factor (TGF)-β1 gene, which codes a pleiotropic cytokine expressed in a variety of cells, is a susceptibility allele for cerebral infarction in Japanese type 2 diabetic patients.     

MTHFR gene polymorphism is susceptible to diabetic retinopathy but not to diabetic nephropathy in Japanese type 2 diabetic patients

AIMS: Previously, we have proposed that methylenetetrahydrofolate reductase (MTHFR) gene polymorphism (C677T) could be a risk factor for diabetic retinopathy. To support our suggestion, we examined in detail the association of MTHFR polymorphism with diabetic retinopathy and nephropathy in Japanese type 2 diabetic patients. METHODS: Subjects (n=190) were free of cardiovascular diseases and were not on hemodialysis. Retinopathy was assessed according to fundamental differentiation; nephropathy was determined according to urinary albumin level; and MTHFR genotype was determined by polymerase chain reaction-restriction fragment length polymorphism. We also analyzed how hyperglycemia affected these three conditions in 131 patients with glycosylated hemoglobin > or =6.5% and fasting blood sugar > or =110 mg/dl. RESULTS: The frequency of 677T/677T homozygous subjects with retinopathy was higher than the frequencies of the other two genotypes, and a significant difference was observed in the distribution of the genotypes (677C/677C, 41.9%; 677C/677T, 31.1%; 677T/677T, 61.5%; P<.05). The susceptibility of 677T/677T homozygote to retinopathy approached significance [odds ratio (OR)=2.17; 95% confidence interval (95% CI)=0.87-5.42]. However, in the population with hyperglycemia, the 677T/677T homozygote modified the risk for retinopathy (OR=4.30; 95% CI=1.42-13.1), especially the risk for nonproliferative retinopathy. In contrast, the 677T/677T homozygote did not affect the risk for nephropathy (OR=1.17; 95% CI=0.45-3.05), even in subjects with hyperglycemia (OR=1.50; 95% CI=0.50-4.48). CONCLUSIONS: Our results are highly suggestive of an important role for MTHFR genotype in susceptibility to retinopathy under hyperglycemia, but not to nephropathy. Preventive therapies based on MTHFR polymorphism could delay the onset of retinopathy in type 2 diabetic patients.     

Relationship between polymorphisms 804C/A and 252A/G of lymphotoxin-alpha gene and -308G/A of tumor necrosis factor alpha gene and diabetic retinopathy in Japanese patients with type 2 diabetes mellitus

To clarify whether polymorphisms of the lymphotoxin-alpha (LTA) gene and tumor necrosis factor alpha (TNF-alpha) gene were related to diabetic retinopathy (DR), we performed a case-control study in 251 Japanese patients with type 2 diabetes mellitus participating in a multicenter research protocol. Genetic analyses were performed by using a fluorescent allele-specific DNA primer assay system. Diabetic retinopathy was diagnosed in a masked manner by an independent ophthalmologist using fundus photographs and was classified as nondiabetic retinopathy (NDR), nonproliferative retinopathy (NPDR), and proliferative retinopathy (PDR). The results showed that the genotype frequencies of 804C/A in exon 3 and 252A/G in intron 1 of the LTA gene were not significantly different among patients with NDR, NPDR, and PDR. A allelic frequency of the TNF-alpha gene (-302A/G in promoter) was also identical among NDR, NPDR, and PDR groups. Multivariate logistic regression analyses showed that significant associations with DR were glycosylated hemoglobin level and diabetes duration, but not polymorphisms of the LTA gene or TNF-alpha gene. In conclusion, the present study showed no association between polymorphisms 804C/A and 252A/G of the LTA gene and -302A/G of the TNF-alpha gene and DR in Japanese type 2 diabetic patients.     

Adiponectin gene polymorphism (G276T) is not associated with incipient diabetic nephropathy in Japanese type 2 diabetic patients

A single-nucleotide polymorphism (SNP) G276T in the adiponectin gene has been associated with lower plasma adiponectin levels and insulin resistance, which are related to the prevalence of type 2 diabetes or diabetic complications of macroangiopathy. We performed a case-control study to examine whether the SNP276 of the adiponectin gene was also related to early diabetic nephropathy. SNP276 was examined with genomic DNA obtained from 108 type 2 diabetic patients with microalbuminuria (urinary albumin creatinine ratio [ACR] between 30 mg/g x Cr and 300 mg/g x Cr; case subjects), and 208 patients with normoalbuminuria (ACR < 30 mg/g x Cr; control subjects). The genotype distribution and G allele frequency of SNP276 in the case subjects (0.71) did not significantly differ from the control subjects (0.69). There were no differences among the genotypes of the adiponectin gene regarding age, duration of diabetes, body mass index (BMI), hemoglobin A(1c) (HbA(1c)), serum lipids, serum creatinine, and plasma adiponectin levels. These data suggest that SNP276 of the adiponectin gene is not an independent risk factor for incipient diabetic nephropathy in Japanese type 2 diabetic patients.     

Relationship between diabetic retinopathy and vascular endothelial function in elderly type 2 diabetic Japanese patients without cardiovascular disease

Background:   Many recent studies point to the importance, in diabetic patients, of vascular endothelial function as an early marker of not only macrovascular complications but also of microangiopathy. The aim of this study is to investigate the relationship between diabetic retinopathy and endothelial function in elderly diabetic patients by using brachial artery flow-mediated dilation (FMD).
Methods:   We studied 71 type 2 diabetic patients aged 65 years or older without cardiovascular diseases. The subjects were categorized as three groups: (i) without diabetic retinopathy ( n  = 49); (ii) with non-proliferative diabetic retinopathy group ( n  = 15); and (iii) those with preproliferative or proliferative diabetic retinopathy ( n  = 7). Brachial artery FMD measurement was performed by high-resolution ultrasonography. The Kruskal–Wallis test, the χ² test and multivariate logistic regression analysis were used to identify associations between both retinopathy and clinical characteristics and FMD.
Results:   There were no differences in clinical characteristics between the three groups. FMD of the three groups were significantly decreased correlating with the severity of retinopathy (8.03% vs 5.40% vs 2.30%; P  = 0.003). Multivariate logistic regression analysis showed that there was a significant correlation between diabetic retinopathy and FMD (odds ratio 0.801; P  = 0.009).
Conclusion:   Our study suggests that FMD has a relation to microangiopathy in elderly diabetic subjects. Prospective studies will be required to determine whether this test has any clinical use for identifying elderly diabetic patients who are likely to develop diabetic retinopathy.     

Risk factors for the development of diabetic retinopathy in Japanese type 2 diabetic patients

This study investigated the risk factors for development of diabetic retinopathy (DR) in 787 type 2 diabetic patients with no retinopathy at the first visit. The subjects were followed up for at least 3 years (mean, 6.7 years). Among the baseline factors, significant correlations were observed between the development of DR and HbA1c (P < 0.0001), the method of therapy (P < 0.005), the duration of diabetes at the first visit (P < 0.005) and the past maximal body mass index (BMI) (P < 0.01). No significant correlation was found with the blood pressure, age, gender, TC or BMI. Among the follow-up variables, the mean HbA1c (P < 0.0001) and duration of diabetes (P < 0.001) correlated significantly with DR development, whereas the blood pressure and age did not. We found that a 1% decrease in HbA1c led to a 35% reduction in the risk of development of DR during the follow-up. The patients whose HbA1c at the first visit was higher than the median value of 8.2% showed a higher probability of development of DR during the next 3 years even when the same blood glucose control was maintained during the follow-up. In conclusion, our study demonstrated that the most important risk factor influencing the development of DR was the blood glucose control. Moreover, we found that the glycemic level at the first visit also influenced the development of DR.     

The relationships between type 2 diabetic retinopathy and VEGF-634G/C and VEGF-460C/T polymorphisms in Han Chinese subjects

ObjectiveTo investigate how VEGF-634G/C and VEGF-460C/T SNPs are related to diabetic retinopathy (DR) in Han Chinese subjects from the Shijiazhuang region of China.MethodsTotally 376 DM cases were divided into non-proliferative diabetic retinopathy (NPDR) group (n = 124), proliferative diabetic retinopathy (PDR) group (n = 108), and diabetes without retinopathy (DWR) group (n = 144). PCR/LDRwas utilised to detect and assess the genotypes and allele distribution frequencies at the VEGF-634G/C and VEGF-460C/T loci in each group.ResultsThe differences between NPDR, PDR and DWR groups were not significant in genotypes and allele distribution frequencies at VEGF-634G/C locus (P > 0.05). But there were significant differences between NPDR and DWR groups in genotypes (P = 0.013) and allele distribution frequencies (P = 0.002) at VEGF-460C/T locus, at which CT + CC genotypes were associated with a reduced risk of developing NPDR. There were no significant differences in genotypes (P = 0.759) or allele distribution frequencies (P = 0.433) at VEGF-460C/T locus between PDR and DWR groups.ConclusionsAmong Chinese Han individuals with type-2 DM, polymorphism − 634G/C of the VEGF gene was not correlated with NPDR or PDR; however, polymorphism-460C/T of the VEGF gene was correlated with NPDR, and C allele was associated with lower NPDR risk than T allele.     

Chimerin 2 genetic polymorphisms are associated with non-proliferative diabetic retinopathy in Taiwanese type 2 diabetic patients

AimTo investigate whether chimerin 2 (CHN2) genetic polymorphisms were associated with the susceptibility to diabetic retinopathy (DR) in Taiwanese individuals with type 2 diabetes.MethodsThis case-control study comprised of 171 individuals with DR and 548 without DR. Four rs39059, rs2023908, rs1002630 and rs1362363 polymorphism of CHN2 were genotyped for each subjects. All subjects underwent a complete ophthalmologic examination, and basic information (age, gender, age at diagnosis of diabetes, and ocular history of the patient) was record. Several clinical parameters (systolic and diastolic blood pressure, waist and hip circumferences, body mass index levels, fasting glucose and HbA1c) were measured.ResultsLogistic regressions were used to analyze odds ratios between SNPs and DR after controlling for gender, systolic blood pressure, waist and hip ratio, duration of diabetes, serum HbA1c levels and nephropathy classification. A protective effect of rs1002630 (GA + AA) and rs1362363 (AG + GG) [odds ratio (OR) (95% confidence interval) = 0.45 (0.22–0.88), 0.66 (0.44–0.99), respectively) was observed. Furthermore, the protective effect of rs1002630 was observed when compared subjects with non-proliferative DR with subjects without DR [OR = 0.25 (95%C.I. = 0.09–0.73)].ConclusionsThis study showed that the rs1002630 of CHN2 were associated with DR risk and non-proliferative DR risk in Taiwanese individuals with type 2 diabetes. Variations at this locus may contribute to the pathogenesis of DR.     

Association of RAGE (p.Gly82Ser) and MnSOD (p.Val16Ala) polymorphisms with diabetic retinopathy in T2DM patients from north India

Aims

The present study aimed to examine the association of RAGE (p.Gly82Ser) and MnSOD (p.Val16Ala) polymorphisms with diabetic retinopathy (DR) in north Indian T2DM patients.

Methods

In this case-control association study, 758 T2DM patients were recruited. 446 with retinal neovascularization, microneurysms and hemorrhages were considered as cases (DR) and 312 patients with T2DM and no clinical signs of retinopathy (DNR), were recruited as controls. Genotypes for RAGE (p.Gly82Ser) and MnSOD (p.Val16Ala) polymorphisms were generated by direct sequencing of amplified products.

Results

Genotype distribution of p.Gly82Ser (RAGE) and p.Val16Ala (MnSOD) polymorphisms were significantly different between DR and DNR (p < 0.05) whereas distribution of allele frequency did not differ significantly (p > 0.05). A significantly higher frequency of homozygous Ser82 genotype in DR patients was detected compared with DNR (2.4% vs 0.64%) for p.Gly82Ser (RAGE) polymorphism whereas there was a higher frequency of homozygous Ala16 genotype for p.Val16Ala (MnSOD) polymorphism in DR patients compared with DNR (22.6% vs 19.3%). Binary logistic analyses showed an association of homozygous recessive genotype Ser82 with DR (OR: 2.63%, 95% CI: 0.16–15.88, p < 0.033) for p.Gly82Ser (RAGE) polymorphism. However, we did not find a significant association of p.Val16Ala polymorphism in MnSOD with retinopathy.

Conclusions

The findings indicate a statistically significant association of p.Gly82Ser polymorphism in RAGE with DR in T2DM patients.     

Clinical risk factors and the role of VDR gene polymorphisms in diabetic retinopathy in Polish type 2 diabetes patients

Abstract Evidence exists that some clinical, metabolic and genetic risk factors are associated with the development of diabetic retinopathy (DR). The aim of the study was: (1) to define the prevalence of DR in the examined group of 267 patients with type 2 diabetes mellitus (T2DM) from a Polish population; (2) to identify in crosssectional analysis, the clinical features associated with DR in the study group; and (3) to search for the association of 4 markers of vitamin D receptor (VDR), a candidate gene for vascular complications in diabetes, with DR. The examined group consisted of 146 female and 121 male T2DM patients (mean age at examination: 61.3±9.4 years; age at T2DM diagnosis: 50.0±9.2; T2DM duration: 11.3±7.8 years; body mass index (BMI): 30.5±5.5 kg/m²; HbA1c: 7.8±1.5%). In all patients, the clinical and metabolic profile was determined. Diagnosis of DR was determined by a trained ophthalmologist by ophthalmoscopy after pupillary dilatation. Colour photographic documentation was made. The examined T2DM patients were genotyped for FokI, ApaI, BsmI and TaqI frequent VDR polymorphisms based on the restriction fragment length polymorphism method. The statistical analysis was performed using univariate and multivariate logistic regression (SAS) and haplotype analysis (Haplostat). DR was detected in 85 (31.8%) patients with T2DM. The multivariate analysis revealed that significant predictors of this complication were: never-smoking status (odds ratio 2.2, 95% confidence interval 1.2–4), urea serum level (1.3, 1.1–1.5), HbA1c level (1.4, 1.1–1.8) and insulin treatment (2.7, 1.4–5.1). Other features such as age of T2DM diagnosis, T2DM duration prior to ophthalmic exam, obesity (BMI>30), serum creatinine level, albumin/creatinine ratio and arterial hypertension were univariate predictors of DR, however they lost significance as independent predictors in multivariate analysis. Similarly, the alleles, genotypes, haplotype and haplotype combination of VDR were not associated with the examined complication. However, there was a suggestion of a possible slight association between the fbaT haplotype and DR (p=0.11). In conclusion, our study showed that DR in T2DM patients remains a frequent complication in Polish T2DM patients. We were able to confirm the role of some clinical risk factors, surprisingly including not-smoking status, as was previously shown in the UK Prospective Diabetes Study (UKPDS). VDR gene polymorphisms did not constitute a risk factor for this size of study group.     

Association analysis of -429T/C and -374T/A polymorphisms of receptor of advanced glycation end products (RAGE) gene in Malaysian with type 2 diabetic retinopathy

Conflicting results have been reported in different populations on the association between two particular RAGE gene polymorphisms (-429T/C and -374T/A) and retinopathy in diabetic patients. Therefore this study was designed to assess the association between both gene polymorphisms with retinopathy in Malaysian diabetic patients. A total of 342 type 2 diabetic patients [171 without retinopathy (DNR) and 171 with retinopathy (DR)] and 235 healthy controls were included in this study. Genomic DNA was obtained from blood samples and the screening for the gene polymorphisms was done using polymerase chain reaction-restriction fragment length polymorphism approach. Overall, the genotype distribution for both polymorphisms was not statistically different (p>0.05) among the control, DNR and DR groups. The -429C minor allele frequency of DR group (12.0%) was not significantly different (p>0.05) when compared to DNR group (16.1%) and healthy controls (11.3%). The -374A allele frequency also did not differ significantly between the control and DNR (p>0.05), control and DR (p>0.05) as well as DNR and DR groups (p>0.05). This is the first study report on RAGE gene polymorphism in Malaysian DR patients. In conclusion, -429T/C and -374T/A polymorphisms in the promoter region of RAGE gene were not associated with Malaysian type 2 DR patients.     

中国人2型糖尿病微血管并发症与AGE受体基因Gly82Ser多态性相关研究

目的　探讨 AGE受体 (RAGE)基因 Gly82 Ser多态性与中国人 2型糖尿病微血管并发症间的关系。方法　使用限制性内切酶 Alu I(AG↑ CT)的 PCR- RFL P法 ,检测 10 4例非糖尿病对照者和 15 6例 2型糖尿病伴或不伴肾病、视网膜病变者的 RAGE基因 Gly82 Ser的多态基因型。结果　中国人 RAGE基因 Gly82 Ser多态基因型以 GG型、等位基因以 G型为最多见 ,但频率分布与白种人相比有显著性差异。非 DM对照组与 2型糖尿病伴或不伴有肾病的 4个亚组间、与伴或不伴有视网膜病变的 2个亚组间 ,RAGE基因的 Gly82 Ser多态的基因型 (GG、GS、SS)频率或等位基因 (G、S)频率皆无显著性差异 (Fisher's确切 P值 >0 .0 5 )。结论　 RAGE基因的 Gly82 Ser多态引起的 RAGE功能性氨基酸突变与 2型糖尿病微血管并发症的发生及进展无显著性相关