Gender-specific association of M235T polymorphism in angiotensinogen gene and diabetic nephropathy in NIDDM

Sex difference in human diseases: mechanistic insights and clinical implications

Sex characteristics exhibit significant disparities in various human diseases, including prevalent cardiovascular diseases, cancers, metabolic disorders, autoimmune diseases, and neurodegenerative diseases. Risk profiles and pathological manifestations of these diseases exhibit notable variations between sexes. The underlying reasons for these sex disparities encompass multifactorial elements, such as physiology, genetics, and environment. Recent studies have shown that human body systems demonstrate sex-specific gene expression during critical developmental stages and gene editing processes. These genes, differentially expressed based on different sex, may be regulated by androgen or estrogen-responsive elements, thereby influencing the incidence and presentation of cardiovascular, oncological, metabolic, immune, and neurological diseases across sexes. However, despite the existence of sex differences in patients with human diseases, treatment guidelines predominantly rely on male data due to the underrepresentation of women in clinical trials. At present, there exists a substantial knowledge gap concerning sex-specific mechanisms and clinical treatments for diverse diseases. Therefore, this review aims to elucidate the advances of sex differences on human diseases by examining epidemiological factors, pathogenesis, and innovative progress of clinical treatments in accordance with the distinctive risk characteristics of each disease and provide a new theoretical and practical basis for further optimizing individualized treatment and improving patient prognosis.

Microchip Immunoassays for Monitoring Renal Function: Rapid, Low-Cost, and Highly Sensitive Quantification of Urinary Biomarkers of Diabetic Nephropathy

This study developed low-cost and highly sensitive immunoassay devices possessing the ability to rapidly analyze urine samples. Further, they can quantitatively detect three biomarkers indicating renal injury: monocyte chemotactic protein 1 (MCP-1), angiotensinogen (AGT), and liver-type fatty acid binding protein (L-FABP). The devices were used to successfully estimate the concentrations of the three biomarkers in urine samples within 2 min; the results were consistent with those obtained via conventional enzyme-linked immunosorbent assay (ELISA), which requires several hours. In addition, the estimated detection limits for the three biomarkers were comparable to those of commercially available ELISA kits. Thus, the proposed and fabricated devices facilitate high-precision and frequent monitoring of renal function.

Gender Differences in Diabetic Kidney Disease: Focus on Hormonal, Genetic and Clinical Factors

Diabetic kidney disease (DKD) is one of the most serious complications of both type 1 (T1DM) and type 2 diabetes mellitus (T2DM). Current guidelines recommend a personalized approach in order to reduce the burden of DM and its complications. Recognizing sex and gender- differences in medicine is considered one of the first steps toward personalized medicine, but the gender issue in DM has been scarcely explored so far. Gender differences have been reported in the incidence and the prevalence of DKD, in its phenotypes and clinical manifestations, as well as in several risk factors, with a different impact in the two genders. Hormonal factors, especially estrogen loss, play a significant role in explaining these differences. Additionally, the impact of sex chromosomes as well as the influence of gene-sex interactions with several susceptibility genes for DKD have been investigated. In spite of the increasing evidence that sex and gender should be included in the evaluation of DKD, several open issues remain uncovered, including the potentially different effects of newly recommended drugs, such as SGLT2i and GLP1Ras. This narrative review explored current evidence on sex/gender differences in DKD, taking into account hormonal, genetic and clinical factors.

Associations between angiotensinogen M235T polymorphisms and the risk of diabetic nephropathy: A meta-analysis

AIMS

The aim of the present study was to clarify the potential relationship of angiotensinogen (AGT) M235T polymorphism and diabetic nephropathy (DN) risk.

METHODS

Comprehensive electronic search in Pubmed, Web of Science, EBSCO, Embase, the Cochrane Library and China National Knowledge Infrastructure (CNKI) to find original articles about the association between AGT M235T polymorphism and DN risk published before 27 September 2017. Literature quality assessment was performed with the Newcastle-Ottawa Scale. Heterogeneity across studies was assessed using I² statistics. Random-effects model or Fixed-effects model was used to estimate the odds ratios (ORs) with 95% confidence intervals (CIs). Sensitivity analyses to assess the influence of individual studies on the pooled estimate. Publication bias was investigated using funnel plots and Egger's regression test. Analyses were performed by using Stata 15.0.

RESULTS

Overall, 20 eligible studies involving a total of 3822 cases and 3911 controls were included in our meta-analysis. The results showed that AGT M235T polymorphism significantly increased DN risk in recessive model (T/T versus M/T + M/M: OR = 1.35, 95%CI (1.07-1.69), I² = 63.8%, Z = 2.56, P = 0.010), homozygote model (T/T versus M/M: OR = 1.46, 95%CI (1.11-1.92), I² = 62.4%, Z = 2.69, P = 0.007) and allele model (T versus M: OR = 1.17, 95%CI (1.01-1.35), I² = 72.5%, Z = 2.14, P = 0.032); Subgroup analysis by ethnicity showed that AGT M235T polymorphism significantly increased DN risk in recessive model (T/T versus M/T + M/M: OR = 1.39, 95%CI (1.06-1.81), I² = 66.6%, Z = 2.42, P = 0.016), homozygote model (T/T versus M/M: OR = 1.47, 95%CI (1.08-2.01), I² = 67.7%, Z = 2.47, P = 0.013) and allele model (T versus M: OR = 1.18, 95%CI (1.02-1.37), I² = 69.4%, Z = 2.26, P = 0.024) in Caucasian DM population; Subgroup analysis by clinical subtype of DM also showed that AGT M235T polymorphism significantly increased DN risk in recessive model (T/T versus M/T + M/M: OR = 1.28, 95%CI (1.05-1.57), I² = 21.3%, Z = 2.40, P = 0.016), homozygote model (T/T versus M/M: OR = 1.41, 95%CI (1.04-1.92), I² = 30.2%, Z = 2.23, P = 0.026) and allele model (T versus M: OR = 1.14, 95%CI (1.03-1.28), I² = 35.5%, Z = 2.44, P = 0.015) in type 1 diabetes patients.

CONCLUSION

Our study showed that AGT M235T homozygous mutation significantly increase DN risk in Caucasian DM population and type 1 diabetes patients.

Angiotensin II receptor type 1 A1166C modifies the association between angiotensinogen M235T and chronic kidney disease

Single nucleotide polymorphisms (SNPs) in renin-angiotensin system (RAS) genes are associated with RAS imbalance and chronic kidney disease (CKD). We performed a case-control study and meta-analysis to investigate the association between angiotensinogen (AGT) M235T polymorphism and CKD. A total of 634 patients with end-stage renal disease and 739 healthy controls were studied. We also searched PubMed and the Cochrane Library to identify prospective observational studies published before December 2015. We found that the TT and MT genotypes were associated with a higher risk of CKD than the MM genotype (odds ratio [OR]: 3.56; 95% confidence interval [CI]: 1.14-11.16 and OR: 2.93; 95% CI: 0.91-9.46, respectively). Thirty-eight study populations were included in the meta-analysis. The T allele was associated with a higher risk of CKD than the M allele in all populations (OR: 1.19; 95% CI: 1.08-1.32). The OR was 1.33 in Asians (95% CI: 1.06-1.67) and 1.10 in Caucasians (95% CI: 1.02-1.18). Evaluation of gene-gene and gene-environment interactions using epistasis analysis revealed an interaction between AGT M235T and angiotensin II receptor type 1 A1166C in CKD (OR: 0.767; 95% CI: 0.609-0.965). Genetic testing for CKD in high-risk individuals may be an effective strategy for CKD prevention.

Role of angiotensin converting enzyme and angiotensinogen gene polymorphisms in angiotensin converting enzyme inhibitor-mediated antiproteinuric action in type 2 diabetic nephropathy patients

AIM

To investigate the role of genetic variants of angiotensin converting enzyme (ACE) and angiotensinogen (AGT) genes in the antiproteinuric efficacy of ACE inhibitor therapy in diabetic nephropathy (DN) patients.

METHODS

In the present study, 270 type 2 diabetes mellitus patients with nephropathy were enrolled and treated with ACE inhibitor (ramipril) and followed at 6 mo for renal function and albumin excretion by estimating serum creatinine, end stage renal disease, and albumin/creatinine ratio (ACR) in urine. Genotyping of ACE I/D and AGT M235T polymorphisms were performed by using primer specific polymerase chain reaction (PCR) and PCR-RFLP techniques, respectively.

RESULTS

Forty-eight percent of DN patients (responders) benefited with respect to proteinuria from ACE inhibitor therapy at 6 mo follow-up. A significant reduction in ACR was observed after 6 mo treatment with ACE inhibitor irrespective of whether DN patients were micro-albuminuric (≥ 30 and < 300 mg/g creatinine) or macro-albuminuric (≥ 300 mg/g creatinine) at the time of enrollment. However, macro-albuminuric patients (55%) showed better response to therapy. A reduction in urinary ACR was found independent of genotypes of ACE I/D and AGT M235T polymorphisms although macro-albuminuric patients having TT genotype showed statistically insignificant increased response (72%).

CONCLUSION

ACE inhibitor therapy reduced urinary ACR by ≥ 30% in 50% of DN patients and the response is independent of ACE I/D and AGT M235T polymorphisms.

Gender specific association of RAS gene polymorphism with essential hypertension: a case-control study

Renin-angiotensin system (RAS) polymorphisms have been studied as candidate risk factors for hypertension with inconsistent results, possibly due to heterogeneity among various genetic and environmental factors. A case-control association study was conducted to investigate a possible involvement of polymorphisms of three RAS genes: AGT M235T (rs699), ACE I/D (rs4340) and G2350A (rs4343), and AGTR1 A1166C (rs5186) in essential hypertensive patients. A total of 211 cases and 211 controls were recruited for this study. Genotyping was performed using PCR-RFLP method. The genotype and allele distribution of the M235T variant differed significantly in hypertensives and normotensives (OR-CI = 2.62 (1.24–5.76), P = 0.006; OR-CI = 0.699 (0.518–0.943), P = 0.018), respectively. When the samples were segregated based on sex, the 235TT genotype and T allele were predominant in the female patients (OR-CI = 5.68 (1.60-25.10), P = 0.002; OR-CI = 0.522 (0.330–0.826), P = 0.005) as compare to the male patients (OR-CI = 1.54 (1.24–5.76), P = 0.34; OR-CI = 0.874 (0.330–0.826), P = 0.506), respectively. For ACE DD variant, we found overrepresentation of “I”-allele (homozygous II and heterozygous ID) in unaffected males which suggest its protective role in studied population (OR-CI = 0.401 (0.224–0.718); P = 0.0009). The M235T variant of the AGT is significantly associated with female hypertensives and ACE DD variant could be a risk allele for essential hypertension in south India.

Tubulointerstitial disease in diabetic nephropathy

Diabetes mellitus is the major cause of end stage renal disease (ESRD). We cannot predict which patient will be affected. ESRD patients suffer an extremely high mortality rate, due to a very high incidence of cardiovascular disease. Several randomized, prospective studies have been conducted to quantify the impact of strict glycemic control on morbidity and mortality, and have consistently demonstrated an association between strict glycemic control and a reduction in ESRD. Within the past 20 years, despite the implementation of treatments that were presumed to be renoprotective, diabetes mellitus has continued to rank as the leading cause of ESRD, which clearly indicates that we are still far from understanding the mechanisms involved in the initiation of ESRD. Progressive albuminuria has been considered as the sine qua non of diabetic nephropathy, but we know now that progression to diabetic nephropathy may well happen in the absence of initial microalbuminuria. The search for new biomarkers of early kidney damage has received increasing interest, since early identification of the pathways leading to kidney damage may allow us to adopt measures to prevent the development of ESRD. Most of these biomarkers are deeply influenced by environment, genetics, sex differences, and so on, making it extremely difficult to identify the ideal biomarker to target. At present, there are no new drugs that come close to providing the solutions we desire for our patients (ie, reducing complications). Even when used in combination with standard care, renal complications are, at best, only modestly reduced, at the considerable expense of additional pill burden and exposure to serious off-target effects. In this review, some of the hypothesized mechanisms of this heterogeneous disease will be considered, with particular attention to the tubule–interstitial compartment.

Gender-specific care of diabetes

Diabetic men have benefited in the last 30 years from a significant improvement in total and cardiovascular mortality, whereas diabetic women have had no improvement at all. Moreover, recent research focused on the role of sex hormones in glucose homeostasis, and might account for different pathophysiologic mechanisms in the development of diabetes-related complications. Thus, care of diabetic women is a challenge that requires particular attention. The available data regarding gender-specific care of diabetes mellitus are uneven, rich in some domains but very poor in others. The large prospective trials performed in the last 20 years have assumed that the natural history of diabetes mellitus in men and women, as well as the efficiency of glucose-lowering therapies and management of hyperglycemic-related complications, could be attributable without distinction to men and women. We propose in this paper to analyze the published medical literature according to the specific management of diabetes mellitus in women, and to try to distinguish some particular features. We found important distinctions between diabetic men and women regarding the patterns of abnormalities of glucose regulation, epidemiology, development of diabetes-related complications, ischemic heart disease, morbidity and mortality, impact of cardiovascular risk factors, development of the metabolic syndrome, depression and osteoporosis, as well as the impact of lifestyle modifications or primary and secondary preventions on cardiovascular risk factors, and finally medical therapeutics. Moreover, special considerations were given to some particular aspects of the medical life in diabetic women, such as the features of gestational diabetes mellitus and the management of pregnancy in pregestational diabetic women, use of contraception, hormone-replacement therapy and polycystic ovary syndrome.

Identification of gene variants in NOS3, ET-1 and RAS that confer risk and protection against microangiopathy in type 2 diabetic obese subjects

The study aim was to investigate NOS3 VNTR, NOS3 G894T, EDN1 C8002T, ACE I/D, AGT M235T and AGTR1 A1166C in nonobese and obese T2DM patients, and their interaction with the incidence of microangiopathy. T2DM subjects (n=250; 166 nonobese, and 84 obese) were genotyped for the gene variants by PCR/RFLP. The interaction of these polymorphisms with obesity and their contribution to microangiopathy were analyzed by multivariate regression analysis. A higher frequency of NOS3 4a allele was found in obese (P=0.027) vs. nonobese subjects. ACE D (P=0.009) and AGT 235T (P=0.026) alleles were associated with the reduced risk of diabetic nephropathy in nonobese and obese patients, respectively. In obese subjects, NOS3 4a (P=0.011) had a converse effect to NOS3 894T (P=0.043), and EDN1 8002T (P=0.035) on the prevalence of combined microangiopathy (neuropathy/retinopathy/nephropathy) vs. microangiopathy-negative subjects. The study indicates association of RAS variants with obesity and nephropathy, and an opposite effect of NOS3 VNTR and NOS3 G894T on the occurrence of combined microangiopathy.

Role of the renin angiotensin system in diabetic nephropathy

Diabetic nephropathy has been the cause of lot of morbidity and mortality in the diabetic population. The renin angiotensin system (RAS) is considered to be involved in most of the pathological processes that result in diabetic nephropathy. This system has various subsystems which contribute to the disease pathology. One of these involves angiotensin II (Ang II) which shows increased activity during diabetic nephropathy. This causes hypertrophy of various renal cells and has a pressor effect on arteriolar smooth muscle resulting in increased vascular pressure. Ang II also induces inflammation, apoptosis, cell growth, migration and differentiation. Monocyte chemoattractant protein-1 production responsible for renal fibrosis is also regulated by RAS. Polymorphism of angiotensin converting enzyme (ACE) and Angiotensinogen has been shown to have effects on RAS. Available treatment modalities have proven effective in controlling the progression of nephropathy. Various drugs (based on antagonism of RAS) are currently in the market and others are still under trial. Amongst the approved drugs, ACE inhibitors and angiotensin receptor blockers (ARBs) are widely used in clinical practice. ARBs are shown to be superior to ACE inhibitors in terms of reducing proteinuria but the combined role of ARBs with ACE inhibitors in diabetic nephropathy is under debate.

Genetics of diabetic nephropathy

Genetic susceptibility has been proposed as an important factor for the development and progression of diabetic nephropathy, and research efforts have been invested worldwide to identify the susceptibility gene for diabetic nephropathy. Although, several candidate genes were shown to be associated with the disease, the results were not always consistent; most of the genes conferring susceptibility to diabetic nephropathy remain to be identified. Recent development of the single nucleotide polymorphism (SNP) typing technology and collation of information on linkage disequilibrium in the human genome have facilitated genome-wide association studies (GWASs) for investigating novel disease-susceptibility genes across the entire human genome. GWASs are considered a powerful and promising approach and are expected to be useful for identifying convincing susceptibility genes for several common diseases; however, to date, these studies have not been able to completely cover the entire human genome.

Gender-specific care of diabetes mellitus: particular considerations in the management of diabetic women

In the past 30 years, the all-cause mortality and cardiovascular mortality rates for women with diabetes mellitus (DM), in contrast to men, have not declined. Furthermore, the difference between all-cause mortality rates in women with DM and those without DM has more than doubled. This urgently needs addressing. This review will analyse published medical literature relating to the specific management of DM in women and try to identify areas where gender affects care. We have identified specific gender differences in the pathophysiology of glucose homeostasis disorder, diabetes-related complications and any female gender-specific features of women with diabetes, such as contraception and the menopause. These gender-specific features of DM may offer a route to improved care for women and new therapeutic possibilities.

Interaction between poor glycemic control and 9p21 locus on risk of coronary artery disease in type 2 diabetes

CONTEXT

A common allele on chromosome 9p21 has been repeatedly associated with increased risk of coronary artery disease (CAD) in the general population. However, the magnitude of this effect in the population with diabetes has not been well characterized.

OBJECTIVE

To examine the association of the 9p21 variant with CAD in individuals with type 2 diabetes and evaluate its interaction with poor glycemic control.

DESIGN, SETTING, AND PARTICIPANTS

(1) Case-control study of 734 type 2 diabetes patients (322 with angiographically diagnosed CAD and 412 with no evidence of CAD) who were recruited between 2001 and 2006 at the Joslin Clinic, Beth Israel Deaconess Medical Center; and (2) independent cohort study of 475 type 2 diabetes patients from the Joslin Clinic whose survival status was monitored from their recruitment between 1993 and 1996 until December 31, 2004. Participants for both studies were genotyped for a representative single-nucleotide polymorphism at 9p21 (rs2383206) and characterized for their long-term glycemic control by averaging multiple hemoglobin A(1c) (HbA(1c)) measurements taken in the years before study entry.

MAIN OUTCOME MEASURES

For the case-control study, association between single-nucleotide polymorphism rs2383206 and CAD defined as angiographically documented stenosis greater than 50% in a major coronary artery or a main branch thereof was assessed and for the cohort study, cumulative 10-year mortality was documented.

RESULTS

Individuals who were homozygous for the risk allele were significantly more frequent among case than control participants (42.3% vs 28.9P = .0002). This association was unaffected by adjustment for cardiovascular risk factors, but the effect of the risk genotype was significantly magnified (adjusted P for interaction = .048) in the presence of poor glycemic control (worst tertile of the distribution of HbA(1c) at examination). Relative to the CAD risk for patients with neither a 9p21 risk allele nor poor glycemic control, the CAD odds for participants having 2 risk alleles but not poor glycemic control were increased 2-fold (odds ratio [OR], 1.99; 95% confidence interval [CI], 1.17-3.41), whereas the odds for study participants with the same genotype and with poor glycemic control were increased 4-fold (OR, 4.27; 95% CI, 2.26-8.01). The interaction was stronger (adjusted P = .005) when a measure of long-term glycemic control (7-year average rather than most recent HbA(1c)) was used with ORs of 7.83 (95% CI, 3.49-17.6) for participants having 2 risk alleles and a history of poor glycemia and 1.54 (95% CI, 0.72-3.30) for participants with the same genotype but without this exposure. A similar interaction between 9p21 variant and poor glycemic control was observed with respect to cumulative 10-year mortality in the cohort study (43.6% in patients with 2 risk alleles and poor glycemic control, 23.1% in individuals with only the 2 risk alleles, 30.0% in individuals with only poor glycemic control, and 31.6% in individuals with neither factor, P for interaction, = .036).

CONCLUSION

In this study population, the CAD risk associated with the 9p21 variant was increased in the presence of poor glycemic control in type 2 diabetes.

Diminished alveolar microvascular reserves in type 2 diabetes reflect systemic microangiopathy

OBJECTIVE

Alveolar microvascular function is moderately impaired in type 1 diabetes, as manifested by restriction of lung volume and diffusing capacity (DL(CO)). We examined whether similar impairment develops in type 2 diabetes and defined the physiologic sources of impairment as well as the relationships to glycemia and systemic microangiopathy.

RESEARCH DESIGN AND METHODS

A cross-sectional study was conducted at a university-affiliated diabetes treatment center and outpatient diabetes clinic, involving 69 nonsmoking type 2 diabetic patients without overt cardiopulmonary disease. Lung volume, pulmonary blood flow (Q), DL(CO), membrane diffusing capacity (measured from nitric oxide uptake [DL(NO)]), and pulmonary capillary blood volume (V(C)) were determined at rest and exercise for comparison with those in 45 healthy nonsmokers as well as with normal reference values.

RESULTS

In type 2 diabetic patients, peak levels of oxygen uptake, Q and DL(CO), DL(NO), and V(C) at exercise were 10-25% lower compared with those in control subjects. In nonobese patients (BMI <30 kg/m(2)), reductions in DL(CO), DL(NO), and V(C) were fully explained by the lower lung volume and peak Q, but these factors did not fully explain the impairment in obese patients (BMI >30 kg/m(2)). The slope of the increase in V(C) with respect to Q was reduced approximately 20% in patients regardless of BMI, consistent with impaired alveolar-capillary recruitment. Functional impairment was directly related to A1C level, retinopathy, neuropathy, and microalbuminuria in a sex-specific manner.

CONCLUSIONS

Alveolar microvascular reserves are reduced in type 2 diabetes, reflecting restriction of lung volume, alveolar perfusion, and capillary recruitment. This reduction correlates with glycemic control and extrapulmonary microangiopathy and is aggravated by obesity.

Angiotensin converting enzyme insertion/deletion polymorphism and renoprotection in diabetic and nondiabetic nephropathies

Despite the huge amount of studies looking for candidate genes, the ACE gene remains the unique, well-characterized locus clearly associated with pathogenesis and progression of chronic kidney disease, and with response to treatment with drugs that directly interfere with the renin angiotensin system (RAS), such as angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor antagonists (ARA). The II genotype is protective against development and progression of type I and type II nephropathy and is associated with a slower progression of nondiabetic proteinuric kidney disease. ACE inhibitors are particularly effective at the stage of normoalbuminuria or microalbuminuria in both type I and type II diabetics with the II genotype, whereas the DD genotype is associated with a better response to ARA therapy in overt nephropathy of type II diabetes and to ACE inhibitors in male patients with nondiabetic proteinuric nephropathies. The role of other RAS or non-RAS polymorphisms and their possible interactions with different ACE I/D genotypes are less clearly defined. Thus, evaluating the ACE I/D polymorphism is a reliable tool to identify patients at risk and those who may benefit the most of renoprotective therapy with ACE inhibitors or ARA. This may guide pharmacologic therapy in individual patients and help design clinical trials in progressive nephropathies. Moreover, it might help optimize prevention and intervention strategies at population levels, in particular, in countries where resources are extremely limited and 1 million patients continue to die every year of cardiovascular or renal disease.

Genetic predictors of renal failure

BACKGROUND

Both environmental and genetic factors contribute to the development and progression of chronic kidney disease. The completion of the human genome sequence and advances in genomic technology make possible identification of gene variants associated with renal failure.

OBJECTIVE

This review discusses the relevant genetic studies in chronic kidney disease, with particular emphasis on the most common causes of end stage renal failure, diabetic nephropathy and glomerulonephritis.

METHODS

Most of the studies presented were performed in recent years and employed association studies, both population-based and with candidate genes, as well as the genome-wide association and genome-wide scan approaches.

RESULTS/CONCLUSION

Increasing evidence supports an important role of genetic susceptibility in the development and progression of renal failure. Identification of disease genes will allow the identification of patients at high risk and the development of new strategies to prevent or delay the renal disease process.

Angiotensinogen gene T235 variant: a marker for the development of persistent microalbuminuria in children and adolescents with type 1 diabetes mellitus

AIM

We examined genetic polymorphisms in the renin-angiotensin system (RAS) coding for angiotensin I-converting enzyme (ACE) insertion/deletion (I/D) for angiotensinogen (AGT) M235T and angiotensin II receptor type 1 (AGTR1) A1166C as predictors for the development of microalbuminuria (MA) in children with type 1 diabetes mellitus (T1DM).

METHODS

Four hundred fifty-three (215 males, 238 females) T1DM children [median (interquartile range): age, 16.7 years (13.9-18.3); diabetes duration, 6.9 years (3.3-10.8); age at diagnosis, 9.1 years (5.8-11.8)] were followed prospectively from diagnosis until the development of MA (two of three consecutive overnight urine samples with albumin excretion rates of > or =20 and <200 microg/min). Kaplan-Meier survival curves and Cox proportional multivariate model estimated the probability of developing MA and the relative risk for MA among different variables.

RESULTS

MA developed in 41 (9.1%) subjects. The frequencies of genotypes were as follows: ACE-II 112 (25%), ACE-ID 221 (49%), and ACE-DD 117 (26%) (n=450); AGT-MM 144 (32%), AGT-MT 231 (51%), and AGT-TT 77 (17%) (n=452); AGTR1-AA 211 (47%), AGTR1-AC 204 (45%), and AGTR1-CC 37 (8%) (n=452). The cumulative risk for the development of MA was higher in ACE-DD versus ACE-ID/II groups (log-rank test, P=.05), and a trend was noticed when AGT-TT was compared to AGT-MT/MM groups (log-rank test, P=.08). AGT-TT polymorphism conferred a fourfold increased risk for MA compared to AGT-MM/MT (hazard ratio=3.8; 95% confidence interval=1.43-10.3; P=.008).

INTERPRETATION

Our findings suggest that RAS gene polymorphism at AGT M235T is a strong predictor for early MA in young T1DM subjects.

Association of the angiotensinogen M235T and angiotensin-converting enzyme insertion/deletion gene polymorphisms in Turkish type 2 diabetic patients with and without nephropathy

OBJECTIVE

Recent studies have suggested an association between a deletion variant of the angiotensin-converting enzyme (ACE) gene and diabetic nephropathy. However, this finding has not been confirmed by all investigators. Furthermore, an M235T variant of the angiotensinogen (AGT) gene has been associated with hypertension, an important risk factor for the development and progression of diabetic nephropathy.

RESEARCH DESIGN AND METHODS

We investigated the relationship of the ACE insertion/deletion (I/D) and AGT M235T gene polymorphisms in Turkish patients with type 2 diabetes mellitus (DM) with and without diabetic nephropathy. A total of 102 individuals were screened for the presence of the ACE I/D and AGT M235T polymorphism: 46 individuals who had type 2 DM with diabetic nephropathy and, as controls, 56 individuals who had type 2 DM without diabetic nephropathy. Gene polymorphisms were determined by the specific melting temperature (T(m)) values of the resulting amplicons after real-time online polymerase chain reaction and melting curve analysis.

RESULTS

The frequencies of the ACE DD, ID, and II genotypes were 34.8%, 37.0%, and 28.3%, respectively, among type 2 diabetic patients with nephropathy, and 33.9%, 42.9%, 23.2%, respectively (P=.788), in the control subjects without diabetic nephropathy. On the other hand, the frequencies of the AGT MM, MT, and TT genotypes among the same groups were 26.1%, 52.2%, 21.7% and 26.8%, 57.1%, 16.1%, respectively (P=.758).

CONCLUSIONS

There were no differences in the frequencies of the AGT M235T and ACE I/D genotypes between Turkish patients with type 2 DM with and without nephropathy.

Combinational effect of genes for the renin-angiotensin system in conferring susceptibility to diabetic nephropathy

To elucidate the role of the renin-angiotensin system (RAS) in diabetic nephropathy, we examined the association between diabetic nephropathy in a large cohort of Japanese type 2 diabetic patients and polymorphisms within the genes that encode angiotensin-converting enzyme (ACE), angiotensinogen (AGT) and angiotensin II receptor type 1 (AGTR1). Single nucleotide polymorphisms (SNPs) within these genes were genotyped using invader assay in 747 nephropathy cases and 557 control subjects. Eight SNPs within the ACE gene were significantly associated with diabetic nephropathy (P<0.05), including five SNPs in almost complete linkage disequilibrium to the insertion/deletion polymorphism in the 16th intron (P=0.01, odds ratio =1.34, 95% CI 1.07-1.69). Three SNPs within the AGT, including M235T and one SNP in the AGTR1, were also significantly associated with nephropathy (M235T P=0.01, odds ratio =0.74, 95% CI 0.59-0.94). In addition, we found that the allelic mRNA expression corresponding to the 235M allele was significantly higher than that for the 235T allele in normal kidney tissues. Furthermore, we found a significant additional effect of these three genes by a step-wise logistic regression analysis (final empirical P value =0.00005). We concluded that RAS gene polymorphisms may contribute to the susceptibility to diabetic nephropathy in type 2 diabetes.

Gender-specific care of the patient with diabetes: review and recommendations

BACKGROUND

Men and women differ in their experience of diabetes mellitus (DM). For optimal prevention and treatment of the disease, these differences must be acknowledged. Unfortunately, most studies of diabetes have focused almost exclusively on men.

OBJECTIVE

The purpose of this review was to survey the literature about the sex-specific features of DM and to make recommendations for the gender-specific care of patients.

METHODS

An initial literature search was performed with Google Scholar and MEDLINE (1995-2005) using the search terms sex/gender, women, diabetes mellitus, and coronary artery disease, and specific topic headings such as polycystic ovary syndrome. The bibliographies of articles were used extensively to augment the search, and more specific search terms were included. The strength of each recommendation was assessed.

RESULTS

: Even when women were included in clinical trials, investigators typically made no attempt to assess the impact of sex differences on the reported results. Existing studies, however, reveal several differences between men and women with diabetes. The prevalence of DM is growing fastest for older minority women. Women with diabetes, regardless of menopausal status, have a 4- to 6-fold increase in the risk of developing coronary artery disease (CAD), whereas men with diabetes have a 2- to 3-fold increase in risk. Women with diabetes have a poorer prognosis after myocardial infarction and a higher risk of death overall from cardiovascular disease than do men with diabetes. Women with type 2 DM experience more symptoms of hyperglycemia than do their male counterparts. Obesity, an important contributor to type 2 DM, is more prevalent in women. Women with diabetes have an increased risk of hypertension compared with men with diabetes. Women have a more severe type of dyslipidemia than do men (low levels of high-density lipoprotein cholesterol, small particle size of low-density lipoprotein cholesterol, and high levels of triglycerides), and these risk factors for CAD have a stronger influence in women. Oxidative stress may confer a greater increase in the risk of CAD for women with diabetes than for men with diabetes. Many other sex differences in DM are due to women's reproductive physiology. Polycystic ovary syndrome is an important correlate of insulin resistance and the metabolic syndrome. Gestational diabetes mellitus (GDM) increases the risk of cardiovascular disease and type 2 DM. Women are less likely than men to receive aggressive treatment for CAD and to achieve treatment goals. Critical recommendations for women include exercise, testing for CAD, daily aspirin to counteract the prothrombotic state, depression screening, careful treatment to avoid weight gain, long-term follow-up of children of women with GDM, control of risk factors for CAD, and aggressive treatment with coronary angioplasty for CAD. Disease management programs for patients with diabetes have been shown to save money and improve outcomes, and should continue to incorporate information about sex-specific differences in DM as it becomes available.

CONCLUSION

Gender-specific care of the patient with diabetes should be informed by evidence-based recommendations.

Chronic renal insufficiency among Asian Indians with type 2 diabetes: I. Role of RAAS gene polymorphisms

Background

Renal failure in diabetes is mediated by multiple pathways. Experimental and clinical evidences suggest that renin-angiotensin-aldosterone system (RAAS) has a crucial role in diabetic kidney disease. A relationship between the RAAS genotypes and chronic renal insufficiency (CRI) among type 2 diabetes subjects has therefore been speculated. We investigated the contribution of selected RAAS gene polymorphisms to CRI among type 2 diabetic Asian Indian subjects.

Methods

Twelve single nucleotide polymorphisms (SNPs) from six genes namely-renin (REN), angiotensinogen (ATG), angiotensin converting enzyme I (ACE), angiotensin II type 1 receptor (AT1) and aldosterone synthase (CYP11B2) gene from the RAAS pathway and one from chymase pathway were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and tested for their association with diabetic CRI using a case-control approach. Successive cases presenting to study centres with type 2 diabetes of ≥2 years duration and moderate CRI diagnosed by serum creatinine ≥3 mg/dl after exclusion of non-diabetic causes of CRI (n = 196) were compared with diabetes subjects with no evidence of renal disease (n = 225). Logistic regression analysis was carried out to correlate various clinical parameters with genotypes, and to study pair wise interactions between SNPs of different genes.

Results

Of the 12 SNPs genotyped, Glu53Stop in AGT and A>T (-777) in AT1 genes, were monomorphic and not included for further analysis. We observed a highly significant association of Met235Thr SNP in angiotensinogen gene with CRI (O.R. 2.68, 95%CI: 2.01–3.57 for Thr allele, O.R. 2.94, 95%CI: 1.88–4.59 for Thr/Thr genotype and O.R. 2.68, 95%CI: 1.97–3.64 for ACC haplotype). A significant allelic and genotypic association of T>C (-344) SNP in aldosterone synthase gene (O.R. 1.57, 95%CI: 1.16–2.14 and O.R. 1.81, 95%CI: 1.21–2.71 respectively), and genotypic association of GA genotype of G>A (-1903) in chymase gene (O.R. 2.06, 95%CI: 1.34–3.17) were also observed.

Conclusion

SNPs Met235Thr in angiotensinogen, T>C (-344) in aldosterone synthase, and G>A (-1903) in chymase genes are significantly associated with diabetic chronic renal insufficiency in Indian patients and warrant replication in larger sample sets. Use of such markers for prediction of susceptibility to diabetes specific renal disease in the ethnically Indian population appears promising.

Genetics of diabetic nephropathy in type 2 DM: candidate gene analysis for the pathogenic role of inflammation

Hypertension, poor glycemic control and albuminuria are well known risk factors for diabetic nephropathy, but these factors do not explain all of the inter-individual variabilities in the rate of progression to kidney failure. Recent evidence showed that genetic predisposition affected the hyperglycemia-induced nephrotoxicity in patients with type 2 diabetes mellitus (DM). We reviewed the present state of knowledge concerning the relationship between genetics and diabetic nephropathy in type 2 DM. However, the results are inconclusive and the genetic determinants of diabetic nephropathy are not fully understood. In addition, genetic background of nephropathy in type 2 DM was thought to be more complex than in type 1 DM. Recent studies suggested that the inflammation would be an essential component of type 2 DM and its complications. We postulated that increased systemic and/or intrarenal inflammation in high glucose milieu is important in the pathogenesis of nephropathy in patients with type 2 DM. To investigate the impact of inflammation on diabetic nephropathy, we studied several polymorphisms in genes encoding inflammatory cytokine and chemokine in patients with type 2 DM. Among them, -511 C/T in interleukin-1beta (IL-1beta), tandem repeat in IL-1 receptor antagonist (IL-1Ra), -308 G/A in tumour necrosis factor-alpha (TNF-alpha) were significantly associated with an increased risk of kidney failure. In addition, some of them were remarkably different from those previously reported in the NCBI or literature based on the western population. Our results suggest that inflammation could play a pathogenic role in diabetic nephropathy in type 2 DM. A better understanding of genetic factors predisposing to diabetic nephropathy would not only help to identify diabetic patients at risk, but also be helpful to unveil the pathogenesis of DN.

Angiotensinogen M235T gene variants and its association with essential hypertension and plasma renin activity in Malaysian subjects: a case control study

BACKGROUND

Essential hypertension is a major public health concern worldwide where its prevalence accounts for various cerebrovascular diseases. A common molecular variant of angiotensinogen (AGT), the precursor of potent vasoactive hormone angiotensin II, has been incriminated as a marker for genetic predisposition to essential hypertension in some ethnics. This case-control study was designed not only to determine the association of the AGT M235T gene variants with essential hypertension, but also its relationship to Plasma Renin Activity (PRA) in subjects attending the Health Clinic, Kuala Lumpur, Malaysia.

METHODS

The study involved 188 subjects, 101 hypertensives and 87 normotensives. Consents were obtained from all the participated subjects. M235T gene variants were investigated using allele specific polymerase chain reaction and PRA was determined by radioimmunoassay. Hypertensinogenic factors such as dietary habits, physical activity, smoking and drinking habits were assessed using a pre-tested questionnaire.

RESULTS

The genotype and allele distribution of the M235T variant differed significantly in hypertensives and normotensives (chi2 = 23.184, P < 0.001 and chi2 = 21.482, P < 0.001, respectively). The odds ratio for hypertension was 1.36 (95% confidence interval 1.03-1.80) for subjects with homozygous mutated allele TT of the M235T variant compared with other genotypes or 1.98 (95% confidence interval 1.46-2.67) for those carrying T allele compared to those carrying M allele. Plasma Renin Activity is also significantly higher in hypertensive subjects (PRA = 3.8 +/- 2.5 ngAI/ml/hr for hypertensives, PRA = 2.6 +/- 1.3 ngAI/ml/hr for normotensives, P < 0.001), but was not significantly different between groups of genotypes (P = 0.118).

CONCLUSION

The M235T variant of the AGT is significantly associated with essential hypertension whereas the genotype TT or allele T is a possible genetic marker or risk factor for hypertension in Malaysian subjects.

Different gender-associated genotype risks of Wegener's granulomatosis and microscopic polyangiitis

Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA) are systemic small vessel vasculitides associated with ANCA (AAV). Predominant Th1 and Th2 cytokine patterns have been reported for WG and MPA, respectively. Consequently, genotypes suppressing Th1 responses or augmenting Th2 responses may be more frequent in MPA than in WG. Transforming growth beta1 (TGF-beta1) and interleukin-10 (IL-10) genes may modify the course of vasculitis. Therefore, we investigated associations between genotype frequencies of functional polymorphisms of these cytokine genes and clinical manifestations in AAV. One hundred sixty-one AAV patients and 153 healthy blood donors were genotyped for the biallelic polymorphism in codon 25 of the TGF-beta1 gene and the biallelic polymorphism at position -1082 of the IL-10 gene. No difference was found for TGF-beta1 codon 25 polymorphism between control and patient groups. In contrast, a significant shift toward the homozygous AA genotype of the IL-10 (-1082) polymorphism was found in WG (25%, p<0.005) and MPA patients (39%; p<0.00001) compared to controls (10.5%). Furthermore, in MPA the AA homozygous genotype was significantly more frequent in females (62.5%) compared to males (20%, p<0.05). A contribution of the TGF-beta1 codon 25 polymorphism to the susceptibility-defining genetic backgrounds of AAV appears unlikely. In contrast, our findings suggest a role of the enhanced IL-10 (-1082) PM in WG and MPA with a significant gender difference in MPA.

Microsatellite DNA polymorphism of human adrenomedullin gene in type 2 diabetic patients with renal failure

BACKGROUND

Adrenomedullin (AM) is a hypotensive peptide widely produced in the cardiovascular organs and tissues such as the heart, kidney, and the vascular cells. We have previously cloned and sequenced the genomic DNA encoding human AM gene, and determined that the gene is located in the short arm of chromosome 11. The 3'-end of the gene is flanked by the microsatellite marker of cytosine adenine (CA) repeats. In this study, we investigated the association between DNA variations in AM gene and the predisposition to develop nephropathy in type 2 diabetes mellitus.

METHODS

Genomic DNA was obtained from the peripheral leukocytes of 233 normal healthy subjects (NH), 139 type 2 diabetic patients on hemodialysis (DM-HD), 106 control patients with type 2 diabetes without nephropathy (DM-C) and 318 hemodialysis patients due to chronic glomerulonephritis (CGN-HD). The genomic DNA was subject to polymerase chain reaction (PCR) using a fluorescence-labeled primer, and the number of CA repeats were determined by polyacrylamide gel electrophoresis (PAGE).

RESULTS

In our Japanese subjects, there existed four types of alleles with different CA-repeat number; 11, 13, 14, and 19. The frequencies of these alleles were 11: 27.7%, 13: 32.8%, 14: 35.6%, and 19: 3.9% in NH. These allele frequencies were not significantly different in DM-C and CGN-HD. However, DM-HD showed significantly different distribution of allele frequency from other groups (chi 2 = 18.9, P = 0.026). Namely, the frequency of 19-repeat allele in DM-HD was higher (9.0%) than NH, DM-C, and CGN-HD (P = 0.005, 0.041, and 0.004, respectively).

CONCLUSION

The microsatellite DNA polymorphism of AM gene may be associated with the genetic predisposition to develop nephropathy in Japanese patients with type 2 diabetes mellitus.

Effects of gender on the renin-angiotensin system, blood pressure, and renal function

Recent studies have identified key gender differences in cardiovascular function, renal hemodynamics, and the renin-angiotensin system. Extensive epidemiologic evidence has shown a clear gender difference in cardiovascular and renal disease progression, whereby female sex appears to be protective. The mechanisms underlying this phenomenon are unknown, but likely reflect the aforementioned sex differences in common pathophysiologic pathways. This review focuses on studies examining sex differences in these underlying pathways, which together may provide a plausible mechanism for the gender disparity in clinical outcomes.

Angiotensinogen M235T and chymase gene CMA/B polymorphisms are not associated with nephropathy in type II diabetes

BACKGROUND

Several studies have suggested that the same genetic factors may be involved in the predisposition to both essential hypertension and 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. This study examines a possible association between angiotensinogen M235T and chymase gene CMA/B polymorphisms with the presence of nephropathy in type II diabetic Caucasians.

METHODS

For the purposes of the study, 323 microalbuminuric and 127 overt proteinuric cases, together with 243 normoalbuminuric controls with long-duration diabetes were selected from a group of 941 type II diabetic patients with established renal status.

RESULTS

No differences in the genotype distributions or allele frequencies of the examined polymorphisms between the study groups were observed. The study groups were also stratified by gender, diabetes duration, level of glycaemic control, body mass index, hypertension, and retinopathy status, but still no distortion in the distributions of genotypes of any of the examined polymorphisms in any of the strata was shown.

CONCLUSIONS

Our study provided evidence against an association between angiotensinogen M235T or chymase gene CMA/B polymorphisms and the presence of incipient or overt nephropathy in Caucasian patients with type II diabetes.

Angiotensin I-converting enzyme gene insertion/deletion and angiotensinogen M235T polymorphisms: risk of chronic renal failure. End-Stage Renal Disease Study Group

BACKGROUND

Chronic renal failure (CRF) is a complex phenotype that results from an underlying kidney disease and superimposing environmental and genetic factors. The aim of our study was to evaluate the role of polymorphisms in the genes encoding for components of the renin-angiotensin system (RAS) in the development and/or progression of CRF.

METHODS

Two hundred forty-seven family trios (patients with CRF and both parents; 120 with primary chronic glomerulonephritis, 80 with interstitial nephritis, and 47 with type 1 diabetes with nephropathy) were examined, and transmission/disequilibrium test (TDT) was used to evaluate allele transmission from heterozygous parents to affected offspring.

RESULTS

The D allele of the angiotensin I-converting enzyme (ACE) gene insertion/deletion polymorphism was transmitted significantly more frequently than expected for no association among all examined trios and in the subgroup of patients with interstitial nephritis. The angiotensinogen 235T allele was transmitted significantly more frequently to patients with CRF than expected for no association, but the effect was seen only in patients with interstitial nephritis. The presence of the DD or ID genotype was associated with a faster rate of decline of renal function, which was not observed for the angiotensinogen M235T polymorphism. For chymase gene and angiotensin II receptor type 1 gene, allele transmission did not deviate significantly from a random proportion of 50:50%.

CONCLUSIONS

The results of this study suggest that ACE gene insertion/deletion and angiotensinogen M235T polymorphisms contribute to the increased risk for the development of CRF, but the magnitude of the effect within subsets of patients with specific etiologies of CRF must be evaluated further.

Genes and renal disease

The identification of genetic linkage between polymorphic markers and common kidney diseases, including focal and segmental glomerulosclerosis and diabetic nephropathy, clearly demonstrates that inherited factors contribute to renal failure susceptibility. These breakthroughs reveal the powerful contribution that molecular genetic techniques can make in the search for inherited factors that initiate renal failure and lead to its progression. Additionally, the environmental factors predisposing to nephropathy will be more readily detectable when evaluated in genetically similar populations. This manuscript reviews the developments in genetic epidemiology and molecular genetics of chronic renal failure.

Protection from vascular risk in diabetic hypertension

Diabetes mellitus is a metabolic disorder characterized by hyperglycemia and associated with a high incidence of complications affecting both the microvascular and the macrovascular systems. Macrovascular disease affects the coronary arteries, the cerebral vessels, and the large peripheral arteries of the lower extremities. Microangiopathy affects the kidneys, eyes, and nerves. Both forms of complication are major causes of death and disability in diabetes. The precise pathophysiology of these vascular complications is becoming better understood, but specific treatment and prevention remain complex.

Synergistic effect of angiotensin-converting enzyme and angiotensinogen gene on cardiac hypertrophy

AIMS

There are controversies concerning the association of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism with left ventricular hypertrophy (LVH), and the unclear association between angiotensinogen (ATG) M235T polymorphism and LVH. We investigated both the separate and interactive effects of these two genes on LVH in patients (N=396) with cardiovascular disease and normal healthy volunteers (N=133).

RESULTS

Frequency of DD genotype of ACE gene was significantly (P<0.05) higher in patients with LVH than patients without LVH or normal controls. Frequency of IT genotype of ATG gene in patients with LVH was significantly (P<0.01) greater than that in normal controls or marginally (P=0.1) higher than that in patients without LVH. These findings were also observed in normotensive patients and normal controls after excluding hypertensive patients. Only in patient group, the frequency of DD genotype in the highest quartile of LVMI was significantly greater than that in the lowest quartile (P<0.05). The higher tendency of TT genotype in the highest quartile patients compared with that in the lowest, did not reach statistical significance. In combined genotype analysis, there was a remarkable difference in LVMI between the two extreme double homozygotes only in patient group (156+/-25 versus 109+/-25 g/m2 for TT+DD versus MM+II) (P<0.01). In ANCOVA, the interaction term composed of ACE and ATG genotype was a significant independent variable for LVMI only in the male patient group (P<0.01).

CONCLUSION

The D-allele of ACE and T-allele of ATG gene exert a synergistic effect on cardiac hypertrophy in male patients with cardiovascular diseases, but not in normal healthy population.

Association between AGT codon 235 polymorphism and variation in serum concentrations of creatinine and urea in Canadian Oji-Cree

Finding the genetic determinants of intermediate quantitative traits, such as serum creatinine and urea, might aid in finding the determinants of disease phenotypes, such as renal failure, that are, in part, defined according to threshold values imposed upon such traits. We evaluated the association between common variation in the gene encoding angiotensinogen, AGT, and the serum concentrations of creatinine and urea in non-diabetic Canadian Oji-Cree. We determined genotypes of the AGT codon 235 polymorphism among 502 non-diabetic Oji-Cree. We used multivariate analysis of variance to identify significant determinants of variation in serum concentrations of creatinine and urea and of systolic and diastolic blood pressure. We found significant associations between the AGT codon 235 genotype and serum concentrations of creatinine and urea (p = 0.017 and 0.049, respectively) and systolic blood pressure (p = 0.041). Compared with subjects with the other two genotypes, homozygotes for AGT T235/T235 had significantly lower serum concentrations of creatinine and urea and significantly higher mean systolic blood pressure. The findings suggest that the AGT T235 allele is a determinant of intermediate traits related to renal function in these aboriginal Canadians.

A population study of ethnic variations in the angiotensin-converting enzyme I/D polymorphism: relationships with gender, hypertension and impaired glucose metabolism

BACKGROUND

The presence of the deletion allele of the angiotensin-converting enzyme (ACE) I/D polymorphism is associated with an excess risk of vascular disease and diabetic nephropathy.

OBJECTIVE

To examine the importance of this polymorphism as a determinant of hypertension and impaired glucose metabolism in a population-based study of three ethnic groups and assess the potential modifying effect of gender.

DESIGN

Population-based cross-sectional study in South London. The population-based sample of 1577 men and women, age 40-59 years, was obtained from stratified random sampling of general practice lists where 25% of the residents were born outside the UK. The ACE I/D polymorphism was determined for 1366 individuals (86.6%): 462 whites, 462 of African descent and 442 of South Asian origin.

RESULTS

The genotype frequency within each ethnic group was in Hardy-Weinberg equilibrium. The frequencies were similar in whites and those of African descent (II, ID, DD: 18.4%, 49.6%, 32.0% for whites and 18.4%, 50.5%, 30.9% for those of African descent), but there was a much higher frequency of the II genotype in those of South Asian origin (39.8%, 41.8%, 18.3%; chi2 = 77.6; P < 0.0001). There was no association between the I/D polymorphism and impaired glucose metabolism in any ethnic group. There were also no significant associations between the I/D polymorphism and hypertension in whites and in those of South Asian origin. This contrasts with a highly significant association between the D allele and hypertension in women of African descent (OR = 2.54; 95% CI 1.38-4.65; P = 0.003) but not in men of African descent (0.79; 0.36-1.72) (test for differences between sexes P = 0.023).

CONCLUSIONS

These observations provide estimates of the frequency distribution of the ACE I/D polymorphism in whites, in people of African descent and in people of South Asian origin. Moreover, these results highlight the potential importance of gender-dependent interactions between genetic background and expression of hypertensive phenotype.

Association between AGT T235 variant and microalbuminuria in Canadian Oji-Cree with type 2 diabetes mellitus

OBJECTIVE

To assess the association between the common variation in the gene encoding angiotensinogen, AGT, and the presence of microalbuminuria in Canadian Oji-Cree with type 2 diabetes mellitus.

RESEARCH DESIGN AND METHODS

We compared the frequencies of the AGT promoter and M235T polymorphisms among three subgroups of adult Oji-Cree: 50 subjects who had type 2 diabetes with microalbuminuria, 6 subjects who had type 2 diabetes without albuminuria and 302 non-diabetic, normotensive subjects.

RESULTS

We found the AGT T235 allele was present at a significantly higher frequency, and that T235/T235 homozygotes were significantly more prevalent, among the subjects who had type 2 diabetes with microalbuminuria than among the subjects in the other two groups.

CONCLUSIONS

The findings suggest that the AGT T235 allele is a determinant of the nephropathy susceptibility related to type 2 diabetes in these aboriginal Canadians.

M235T angiotensinogen gene polymorphism and cardiovascular renal risk

OBJECTIVE

In this meta-analysis, we attempted to derive pooled estimates for the putative associations between various cardiovascular-renal disorders and the M235T polymorphism of the angiotensinogen gene.

METHODS

Case-control studies were combined, using the Mantel and Haenszel approach. Joint P values for continuous variables were calculated by Stouffer's method. Continuous measurements reported in different units were expressed on a percentage scale using the intrastudy mean of the MM genotype as denominator.

RESULTS

The computerized database used for this analysis included 69 reports with an overall sample size of 27,906 subjects. Overall, possession of the T allele was associated with an increased risk of hypertension. In comparison with the MM reference group (number of studies, n = 32), the excess risk was 31% (P = 0.001) in TT homozygotes and 11% (P = 0.03) in TM heterozygotes. The sensitivity analysis showed that this association was present only in whites (T allelic frequency, f = 42.2%), but not in blacks (f = 77.0%) or Asians (f = 78.0%). Atherosclerotic complications (n = 12), renal microvascular disorders (n = 13), cardiomyopathy (n = 2) or diabetic retinopathy (n = 3) were not correlated with the M235T polymorphism. Publication bias was observed for hypertension, but not for coronary heart disease, including myocardial infarction, and for microvascular nephropathy. Furthermore, in comparison with the MM control group, the circulating angiotensinogen levels (n = 8) were raised by 11 and 7% (P = 0.01) in TT and TM subjects, respectively. In contrast, plasma levels of the angiotensin I converting enzyme (n = 4) and body mass index (n = 15) were not associated with the T allele.

CONCLUSION

The T allele encoding angiotensinogen is not associated with atherosclerotic or microvascular complications, but in Caucasians behaves as a marker for hypertension. This association, which may have been inflated by publication bias, does not necessarily imply causality.