| BackgroundThe increasing prevalence of type 2 diabetes in the general population makes it the most common diagnosis among patients entering renal replacement therapy. Glycaemic control, hyperlipidaemia, and glomerular as well as systemic hypertension are the major factors contributing to the development of diabetic nephropathy(DN). Like type 1 diabetes, genetic predisposition is an important risk factor of diabetic nephropathy. Several studies have suggested that the same genetic factors may be involved in the predisposition to diabetic nephropathy, but the molecular mechanism underlying this predisposition still remains unclear. In particular, the role of genes involved in blood-pressure regulation and angiotensin II action is still controversial.The association between renin-angiotensin system (RAS) and diabetic nephropathy has been well documented. Angiotensin Ⅱ (Ang Ⅱ) is the major factor contributing to the development of hypertension and diabetic nephropathy. The increased of Ang Ⅱ in plasma and local tissue has been certified in the diabetic nephropathy group, also angiotensin converting enzyme inhibitor therapy could notcompletely prevent the progression of diabetic complication as well as diabetic hypertension.Ang II can be achieved by angiotensin-converting enzyme (ACE) and chymase. Chymase, the rate-limiting enzyme of the RAS system, has been considered to be closely associated with the cardiac-vascular disease as well as hypertension, cardiac hypertrophy, congestive heart failure, atherosclerosis, and diabetic complication.Chymase gene CMA/B polymorphism (G/A transition at position -1903 of the 5' untranscribed region of the gene) was found to have the effect on phenotypic expression of hypertrophic cardiomyopathy. The widespread tissue chymase activity also present in the kidney. In the study we examined the association between chymase gene CMA/B polymorphism and the presence of renal complications in Chinese type 2 diabetes patients.Subject and Methods1. SubjectsIn this study, 130 patients with type 2 diabetic patients were consecutively collected from the hospitalized in the department of endocrinology, Zhejiang Provincial People's Hospital. The population of patients selected for this study has previously been described in detail. These patients were dividied into three groups according to the urinary albumin excretion rate: 40 patients with microalbuminuria, 24 with overt proteinuria and a control group of 66 patients with normoalbuminuria.145 normal controls served as a control group. All subjects were Chinese Han nationality. There was no relationship between individuals in the study population.2. Risk for DNAll paients with diabetes mellitus completed a questionnaire that included demographic data: age, gender , body mass index (BMI) , blood pressure, known diabetes duration and HbA1c levels et al. The status including hypertension, hyperlipimia, smoking, alcohol and family history were investigated.3. Laboratory methods for CMA gene polymorphismDNA was extracted from the periphral blood leukocytes by standard phenol and chloroform method.The G1903A polymorphism of CMA was determined by PCR-RFLP. Amplification was carried out in 25 μl volume containing two primers , by initial denaturation at 95℃ for 5 minute followed by 39 cycles at 94℃ for 30 second, at 55℃ for 15 second, and at 72℃ for 30 second . PCR products were then digested with 3 U Bst XI at 55 ℃ for 3h and digestion products were separated on 2% agarose gels and visualised with ethidium bromide.4. Statistical analysisThe gene counting method was used to estimate the allele and genotype frequencies in patients groups and normal controls. The Hardy-Weinberg equilibrium for the frequencies of genotypes was tested by x2 analysis, x2 analysis was used to compare differences in the distribution of genotypes between patients and the normal subjects and other diabetic nephropathy risk factors in patients. All continuous variables were expressed as mean ± standard deviation, comparison between groups was performed by either t-test or One Way ANOVA analysis. Analysis of risk factors was tested by multiple logistic regression analysis. Statistic analyses were performed with the SPSS for windows 10.0 statistic program package. Values were considered statiscally significant at P value <0.05 (two sided).Results1. Genotype distributions of the chymase gene CMA/B polymorphism tested in the study were in Hardy-Weinberg equilibrium in all of our study groups.2. No differences in the genotype distributions or allele frequencies of the examined polymorphisms between the study groups were observed ( P >0.05).3. The genotype distributions or allele frequencies of Chymase were no differences between non-diabetic nephropathy and diabetic nephropathy. Compared the group of early diabetic nephropathy with the group of delay diabetic nephropathy, there was the same results.4. Among all patients with type 2 diabetes , the clinical data was also analysed . The age, diabetes duration, systemic pressure, fast insulin and fibrinogen levels were observed difference of our study groups, with a markedly increased of diabetes duration and systemic pressure in diabetic nephropathy.5. The study groups on the basis of genotypes of the chymase, were also stratified by gender, diabetes duration, level of glycaemic control, body mass index, hypertension, and retinopathy status et al. Except TC and LDL-C , still no positive difference was found. Compariing to AG group, the level of TC and LDL-C were higher in GG group.Conclusions1. There are genotypes of CMA/B polymorphism in Zhejiang Han population.2. No associations between chymase gene CMA/B polymorphism and type 2 diabetes.3. There is no relationship between chymase gene CMA/B polymorphism and the presence of incipient or overt nephropathy in patients with type 2 diabetes.4. The chymase gene CMA/B polymorphism maybe assosiated with plasma cholesterol levels. The presence of GG genotype might be as a risk factor for high cholesterol level.
|
PDF Full Text Request