Renal disease in relatives of Indo-Asian Type 2 diabetic patients with end-stage diabetic nephropathy

Pancreas transplantation in older patients is safe, but patient selection is paramount

Pancreas transplant outcomes have progressively improved. Despite this, some centers have continued to employ historical age limits for pancreas transplant candidates. We sought to determine the importance of chronological age in determining patient and graft survival rates after pancreas transplantation. A single-center, retrospective study of adult, deceased donor simultaneous pancreas and kidney (SPK) and solitary pancreas transplants (SP, including pancreas transplant alone and pancreas after kidney transplants) in recipients ≥ 55 years (55 + ), occurring between July 1, 1999, and June 30, 2012, was performed. Seven-hundred and forty patients underwent pancreas transplantation, of which 28 patients were 55 + . Patient survival was comparable for younger and older pancreas transplant recipients. Both non-death-censored and death-censored pancreatic graft survival rates were similar in younger and in older patients. Patients aged 45-54 and those aged 55 +  had more frequent cardiovascular events than younger pancreas transplant recipients. There was no difference in renal graft survival for SPK patients when compared with diabetic kidney transplant alone recipients aged 55 years and older. Older pancreas transplant recipients had acceptable long-term patient and graft survival rates, although complications may occur. Chronological age alone should not exclude a patient for pancreas transplant candidacy.

Epidemiology of microvascular complications of diabetes in South Asians and comparison with other ethnicities

Type 2 diabetes mellitus is widely prevalent in South Asians, and has a significant effect on health, as well as the economies of South Asian countries, particularly when the disease is associated with complications. There are certain characteristics associated with the South Asian phenotype that make South Asians especially prone to diabetes, as well as its complications. Microvascular complications cause considerable morbidity and mortality. There are significant differences in the epidemiology of microvascular complications between South Asians and people of other races. There is evidence of higher prevalence of nephropathy and retinopathy in South Asians compared with Caucasians; however, recent studies indicate that this trend seems to be leveling off. Importantly, diabetic neuropathy occurs less frequently in South Asians compared with Caucasians. These observations have important implications in managing South Asian patients with diabetes and microvascular complications.

Low Mannose-Binding Lectin (MBL) genotype is associated with future cardiovascular events in type 2 diabetic South Asians. A prospective cohort study

BACKGROUND

South Asians have a high burden of type 2 diabetes and vascular complications. Vascular inflammation is considered central in the pathophysiology of atherosclerosis, and the complement system is thought to play an important role. Mannose-Binding Lectin (MBL), which activates the lectin pathway of complement activation, has been introduced as a risk marker of vascular damage. The present study explores the association of MBL levels, genotype and cardiovascular events in type 2 diabetic South Asians.

METHODS

We conducted a prospective observational study. A cohort consisting of 168 type 2 diabetic South Asians was followed for a median duration of 7.66 years. At baseline, MBL levels and genotype were determined. The association with future cardiovascular events was assessed by Cox proportional hazard regression.

RESULTS

During follow-up, 31 cardiovascular events occurred in 22 subjects (11 men, 11 women). The O/O genotype was significantly associated with the occurrence of cardiovascular events (hazard ratio 3.42, 95%CI 1.24-9.49, P = 0.018). However, log MBL levels were not associated with the occurrence of cardiovascular events (hazard ratio 0.93, 95% CI 0.50-1.73).

CONCLUSIONS

In type 2 diabetic South Asians, the O/O MBL genotype is associated with cardiovascular events, although single serum MBL levels are not.

Enhanced complement activation is part of the unfavourable cardiovascular risk profile in South Asians

South Asian immigrants in western societies exhibit a high burden of diabetes and subsequent vascular complications. Diabetic vascular complications are associated with vascular inflammation. We hypothesize that enhanced complement activation is involved. Therefore, levels of complement C3 and SC5b-9 - the soluble end product of complement activation - in a group of 200 South Asians were compared with an age- and sex-matched control group of native Caucasians. In addition, the association between complement levels and albuminuria, an indicator of renal damage and a cardiovascular risk marker, was assessed in the diabetic South Asian group. Compared with native Caucasians, South Asians had significantly higher levels of both serum C3 and plasma SC5b-9, even when only non-diabetic South Asians were considered. Diabetic South Asians had significantly higher C3 levels compared with non-diabetic South Asians. In diabetic South Asians, higher levels of SC5b-9 were associated with an increased prevalence of albuminuria (odds ratio 5.4, 95% confidence interval 1.8-15.8). These results suggest that enhanced complement activation is part of the unfavourable cardiovascular risk profile in South Asians.

Lower frequency of the 5/5 homozygous CNDP1 genotype in South Asian Surinamese

We investigated the frequency of the 5/5 homozygous CNDP1 (carnosinase) genotype, which was found to be associated with a reduced risk of developing diabetic nephropathy, in three ethnic groups in The Netherlands. Particularly interesting were the South Asian Surinamese, who have a high prevalence of diabetic nephropathy. Furthermore, we investigated the association between this gene and carnosinase activity in South Asian Surinamese and whether carnosinase was expressed in the kidney. We genotyped 290 South Asian Surinamese, 532 African Surinamese, and 472 White Dutch in a cross-sectional population study. Furthermore, an independent cohort of South Asian Surinamese was genotyped. In this population, carnosinase activity was measured in serum. Immunostaining and in situ hybridization for CNDP1 were performed on kidney tissue. Both South Asian populations had lower frequencies of the 5/5 homozygous genotype than African Surinamese and White Dutch (23.0%, 27.2%, 38.2%, and 41.3%, respectively; chi-square, p<0.001). This genotype showed a lower carnosinase activity in South Asian Surinamese (Wilcoxon rank-sum, p=0.03). CNDP1 was expressed in the kidney. South Asian Surinamese have a lower frequency of the 5/5 homozygous genotype, which was associated with lower carnosinase activity. Our study provides an indication that South Asian Surinamese are genetically at risk for developing diabetic nephropathy.

Central obesity is an independent risk factor for albuminuria in nondiabetic South Asian subjects

OBJECTIVE

South Asians have a high prevalence of central obesity. When the diagnosis of diabetes is made, they have a very high risk of developing renal failure. In the current study, we explored the hypothesis that central obesity is associated with the development of renal injury, before the manifestation of diabetes.

RESEARCH DESIGN AND METHODS

We invited first-degree nondiabetic relatives of South Asian type 2 diabetic patients for investigation of microalbuminuria and diabetes. Subjects who used antihypertensive or antidiabetic medication were excluded. We performed a glucose tolerance test according to the classic World Health Organization criteria. A total of 205 subjects were normoglycemic; we excluded 25 subjects because of impaired glucose tolerance, and 30 subjects were excluded because of de novo diabetes. Central obesity was measured by waist-to-hip ratio (WHR). Albuminuria was measured as albumin-to-creatinine ratio (ACR) in the early-morning urine.

RESULTS

Central obesity was independently related with albuminuria in the 205 normoglycemic subjects. We found no relation of fasting blood glucose or systolic blood pressure with albuminuria. Multivariate analysis for the presence of increased albuminuria (median ACR >0.31 mg/mmol) showed a relative risk of 4.1 for the highest versus the lowest tertile of WHR (P = 0.002).

CONCLUSIONS

Central obesity is an early and independent risk factor for increased albuminuria in normoglycemic South Asian subjects. This could explain the high incidence of diabetic renal disease in South Asians, probably by the mechanism of insulin resistance and endothelial dysfunction in the pre-diabetic state.

Vascular phenotype and subclinical inflammation in diabetic Asian Indians without overt cardiovascular disease

Although Asian Indian (AI) patients with diabetes mellitus type 2 (DM2) are at high risk for cardiovascular disease (CVD), not all patients develop CVD. The vascular phenotype of AI-DM2 without CVD has not been elucidated and may point to protective features. Using baseline data from a clinical trial we provide an initial description of vascular parameters in AI-DM2 compared to Europid Caucasian controls (ECs) matched for age and gender. Endpoints of the study were endothelial function, low-grade systemic inflammation (CRP) and carotid intima-media thickness (cIMT). AIs had longer duration of diabetes, worse glycemic control and more microangiopathy. Both groups demonstrated marked endothelial dysfunction. CRP levels were similar: 1.7 (4.9) mg/L in AIs and 2.8 (3.6) mg/L in ECs. cIMT values were significantly lower in AI-DM2 than EC-DM2 (0.655mm (0.12) versus 0.711mm (0.15), p=0.03). Multiple regression analysis showed that variability in CRP was mainly determined by waist circumference, not by ethnicity. In contrast, ethnicity was a significantly explanatory variable for cIMT. Vascular phenotype of AI-DM2 without CVD was characterized by endothelial dysfunction and relatively low levels of CRP, comparable to EC-DM2 controls. In contrast, lower cIMT values were observed in AI-DM2 despite longer duration of diabetes and worse metabolic control. We propose that mechanisms slowing its progression may have atheroprotective potential in AI-DM2.

Obesity is associated with family history of ESRD in incident dialysis patients

BACKGROUND

Obesity is an established risk factor for chronic kidney disease and aggregates in families. The objective of this study is to examine the relationship between obesity and family history of end-stage renal disease (ESRD).

METHODS

Data were collected from 25,883 incident patients with ESRD in US ESRD Network 6 (Georgia, North Carolina, and South Carolina) dialysis clinics between 1995 and 2003. Family history is defined as a first- or second-degree relative with ESRD. Body mass index (BMI) at dialysis therapy initiation was classified as underweight (BMI < 18.5 kg/m2), normal (BMI, 18.5 to <25 kg/m2), overweight (BMI, 25 to < 30 kg/m2), obese (BMI, 30 to <35 kg/m2), or morbidly obese (BMI > or = 35 kg/m2).

RESULTS

Twenty-three percent of patients reported a family history of ESRD. Of patients reporting a family history of ESRD, 5.5% were underweight, 32.5% had normal BMI, 28.0% were overweight, 17.3% were obese, and 16.7% were morbidly obese. After controlling for age, race, sex, primary cause of ESRD, history of diabetes, history of hypertension, and estimated glomerular filtration rate at dialysis therapy initiation, reported family history of ESRD was associated with being overweight (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.08 to 1.26), obese (OR, 1.25; 95% CI, 1.14 to 1.37), and morbidly obese (OR, 1.40; 95% CI, 1.27 to 1.55).

CONCLUSION

Obesity at dialysis therapy initiation was associated independently with reported family history of ESRD. This finding suggests that behavioral factors, adiposity-related genes, and gene-by-BMI interaction may contribute to familial risk for ESRD. This finding also suggests that management of obesity may be even more important for patients with a family history of ESRD than for the general population.

A population-based assessment of the familial component of chronic kidney disease mortality

BACKGROUND/AIM

While the familial nature of chronic kidney disease (CKD) has been recognized, it has primarily been defined from studies of first-degree relatives of selected sets of cases. The goal of this study is an evaluation of the familial clustering of end-stage renal disease (ESRD) and CKD mortality using a population-based genealogy of Utah. This is the first population-based analysis of the familial component of ESRD and non-ESRD CKD.

METHODS

We have defined two distinct patient groups for this analysis, using individuals with death certificates in the Utah Population Database indicating ESRD (n = 192) and non-ESRD CKD (n = 335) as the cause of death. Two measures of familiality were used: (1) relative risk (RR) of CKD or ESRD death in relatives of cases and (2) an average relatedness statistic, i.e., the Genealogical Index of Familiality.

RESULTS

The RR for dying with ESRD among the first-degree relatives of individuals dying with ESRD is estimated to be 10.1 (p = 0.0007, 95% confidence interval CI 2.76-25.95), but is not significantly elevated among second-degree relatives. The RR for dying with non-ESRD CKD among first- and second-degree relatives of individuals dying with non-ESRD CKD was 3.89 (p = 0.0051, 95% CI 1.43-8.46) and 3.11 (p = 0.04, 95% CI 0.85-7.95), respectively. The Genealogical Index of Familiality statistic demonstrated that the individuals dying with ESRD are significantly more related than expected in this population (p = 0.013); significant excess relatedness was also observed for individuals dying with non-ESRD CKD (p = 0.006), suggesting a familial component for both, with evidence for common environmental and genetic effects.

CONCLUSION

The results of this analysis of individuals dying with ESRD and non-ESRD CKD supports a significant and independent familial component to both conditions, suggesting a heritable factor playing a role.

Epidemiology and risk factors for chronic kidney disease

Kidney disease is highly prevalent in the United States population and groups at high risk for increased prevalence of CKD include individuals with a family history of ESRD, diabetes, hypertension, and cardiovascular disease. Despite the increased risk of ESRD observed for blacks compared with whites, racial disparities in the prevalence of kidney disease have not been consistently demonstrated in the United States population. Although the reasons for discrepancy in risk of ESRD and CKD have not been established, clinicians should be aware that more rapid progression of CKD among blacks is a possible explanation for this observation and that closer monitoring and intensive care of risk factors associated with progressive renal injury is warranted for blacks with CKD and in other high-risk groups. Therapeutic interventions that delay or prevent progressive kidney disease are well established and incorporated into widely disseminated clinical practice guidelines. These interventions include aggressive blood pressure control with agents that block the renin-angiotensin system, reduction of dietary protein to recommended levels for the American diet, weight loss, smoking cessation, and control of hyperlipidemia. These interventions also reduce the risk of cardiovascular disease and should be regarded as essential components of care of CKD. Achieving high levels of medically appropriate care of CKD patients and reduction in risk of progression to ESRD may be delayed by barriers created by individual and regional poverty.

Genetics of common progressive renal disease

Familial aggregation of common chronic kidney diseases provides a unique opportunity to investigate the susceptibility genetic and environmental factors. In the past decade, a wealth of new data has become available concerning the genetic susceptibility leading to numerous nephropathies. Knowledge of the genetic components allows better understanding of initiation and progression of these chronic kidney diseases. In addition, one can envision that identification of genetically susceptible individuals might lead to earlier diagnosis and potential reversal of the current epidemic of end-stage renal disease. The goal of the current discussion is to review various issues pertaining to the role of genetic factors in common chronic kidney diseases, as exemplified by two leading causes of end-stage renal diseases worldwide, nephropathy of type 2 diabetes and IgA nephropathy. The genetic and environmental interplay leading to the nephropathies is highlighted.