Increased prevalence of apolipoprotein E3/E4 genotype among Swedish renal transplant recipients

Apolipoprotein E and plasminogen activator inhibitor 1 gene polymorphism in children with chronic renal insufficiency associated with cardiovascular disease

Background

Cardiovascular disease (CVD) is considered a major cause of death in renal insufficiency (RI). Contributing genetic factors is a recent focus of research. This study aims to elucidate apolipoprotein E (APO-E) and plasminogen activator inhibitor 1 (PAI-1) gene polymorphisms in RI children associated with CVD.

Methods

We studied 50 cases with chronic kidney disease (CKD) associated with CVD, and 30 healthy controls. Study sample was grouped as one on conservative treatment, the second on hemodialysis and the third was posttransplant. PAI-1 and APO-E gene polymorphisms were investigated using allele-specific polymerase chain reaction (AS-PCR) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) respectively.

Results

4G4G and 4G5G were the most common PAI-1 polymorphism denoting high association of 4 G allele in renal insufficiency associated with CVD with absent link to dyslipidemia, echocardiography changes or thrombosis. E3E3 was the most common among APO-E polymorphism without relation to dyslipidemia or thrombosis. Dyslipidemia was significantly linked to thrombosis. The study confirmed the role of dyslipidemia and hemodialysis in promoting thrombosis.

Conclusion

Although PAI 4G Genotyping did not show significant association with echocardiography severity or thrombotic severity, yet genetic expression for high levels of PAI in plasma is expected in response to CRI factors known to trigger its release, in addition to those related to dialysis. APO-E3E3 genotyping showed a significant association with echocardiography severity as it enhances APO-A which contributes to CVD. The current study confirmed a significant association between dyslipidemia and CVD; however, the prevalent patterns 4G and E3E3 did not show a significant association with dyslipidemia. The genetic role for APO-A, B, O, or even other isomers for APO-E should be further studied as well.

An African perspective on the genetic risk of chronic kidney disease: a systematic review

BACKGROUND

Individuals of African ethnicity are disproportionately burdened with chronic kidney disease (CKD). However, despite the genetic link, genetic association studies of CKD in African populations are lacking.

METHODS

We conducted a systematic review to critically evaluate the existing studies on CKD genetic risk inferred by polymorphism(s) amongst African populations in Africa. The study followed the HuGE handbook and PRISMA protocol. We included studies reporting on the association of polymorphism(s) with prevalent CKD, end-stage renaldisease (ESRD) or CKD-associated traits. Given the very few studies investigating the effects of the same single nucleotide polymorphisms (SNPs) on CKD risk, a narrative synthesis of the evidence was conducted.

RESULTS

A total of 30 polymorphisms in 11 genes were investigated for their association with CKD, ESRD or related traits, all using the candidate-gene approach. Of all the included genes, MYH9, AT1R and MTHFR genes failed to predict CKD or related traits, while variants in the APOL1, apoE, eNOS, XPD, XRCC1, renalase, ADIPOQ, and CCR2 genes were associated with CKD or other related traits. Two SNPs (rs73885319, rs60910145) and haplotypes (G-A-G; G1; G2) of the apolipoprotein L1 (APOL1) gene were studied in more than one population group, with similar association with prevalent CKD observed. The remaining polymorphisms were investigated in single studies.

CONCLUSION

According to this systematic review, there is currently insufficient evidence of the specific polymorphisms that poses African populations at an increased risk of CKD. Large-scale genetic studies are warranted to better understand susceptibility polymorphisms, specific to African populations.

Association between Apolipoprotein E Polymorphism and Chronic Kidney Disease in the Korean General Population: Dong-gu Study

Background

Few studies have investigated the association between Apolipoprotein E (APOE) polymorphisms and chronic kidney disease (CKD) in the general population, and their results are inconsistent.

Methods

The current study population was composed of 9,033 subjects aged ≥ 50 years who participated in the baseline survey of the Dong-gu Study, which was conducted in Korea between 2007 and 2010. APOE polymorphisms were identified by polymerase chain reaction, and the estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Disease equation.

Results

Individuals with the APOE E2 allele had significantly lower total and low density lipoprotein cholesterol levels, those with the APOE E4 allele had lower high density lipoprotein (HDL) cholesterol levels, and those with the APOE E3 allele had lower log-triglyceride levels. Adjusting for covariates (sex, age, body mass index, smoking, systolic blood pressure, hypertension, diabetes, total cholesterol, HDL cholesterol, log-transformed triglycerides, and log-transformed albumin to creatinine ratio), mean eGFR was not significantly different among APOE alleles (E2, 69.4 mL/min/1.73 m²; E3, 69.5 mL/min/1.73 m²; E4, 69.4 ml/min/1.73 m²; P = 0.873). Additionally, the odds ratios (ORs) indicated that APOE polymorphisms were not independent risk factors for CKD (OR, 1.07; 95% confidence interval [CI], 0.91 to 1.26 for the E2 vs. E3 allele; OR, 1.01; 95% CI, 0.88 to 1.16 for the E4 vs. E3 allele).

Conclusion

APOE polymorphisms were not associated with either eGFR or CKD in the general Korean population.

Association of apolipoprotein E gene polymorphism with end-stage renal disease and hyperlipidemia in patients on long-term hemodialysis

BACKGROUND

Cardiovascular diseases (CVDs) are the leading cause of death of patients with chronic renal failure. Apolipoprotein E (apoE) plays an important role in the homeostasis of cholesterol and triglycerides.

OBJECTIVE

We aimed to investigate the possible link(s) between apoE gene polymorphism, inflammation and lipoproteins in hemodialysis patients.

METHODS

We studied 109 end-stage renal disease (ESRD) patients and 97 controls. The serum lipids, apolipoproteins, lipoprotein particles, high-sensitivity C-reactive protein (hs-CRP) and total homocysteine (t-Hcy) levels and paraoxonase (PON) activity were determined in our patients. We also analyzed apoE gene polymorphism in the patients and controls.

RESULTS

The analysis of the apoE gene demonstrated a predominance of the e3 allele in both the patients and controls, followed by the e4 and then the e2 alleles. The analysis of the apoE genotype and allele frequencies showed significantly higher e4 allele and E3E4 genotype frequencies and decreased e3 allele and E3E3 genotype frequencies in the patients compared with the controls. The e2, e4 and E3E4 carriers within the ESRD patient population presented an atherogenic lipid profile. However, there were no significant variations in the serum PON activity and the hs-CRP and t-Hcy levels between individuals with different apoE polymorphisms.

CONCLUSIONS

Our findings suggest an association between the e4 allele, E3E4 genotype and ESRD. The apoE polymorphism affects the serum lipoprotein levels, and the ESRD patients who are e4 and e2 allele carriers are more likely to present an atherogenic lipoprotein profile that may be a major factor associated with increased risk of CVD.

Effect of apolipoprotein E gene polymorphism on serum lipid level before and after renal transplantation

OBJECTIVE

To investigate the effect of apolipoprotein E (ApoE) gene polymorphism on lipid metabolism among renal transplant recipients before and after transplantation. No prisoners or organs from prisoners were used in this study.

METHODS

ApoE gene polymorphism was detected with polymerase chain reaction-restriction fragment length polymorphism; serum lipid levels were measured with biochemical methods.

RESULTS

Serum lipid levels in the recipients were increased significantly at 3 months after renal transplantation, and further elevated at 6 months and 1 year. The recipients with higher total serum cholesterol (TC) and triglyceride (TG) levels only accounted for 2.9% and 7.6%, respectively, before renal transplantation; but for 28.6% and 46.7%, respectively, at 3 months (P < .01); 40.0% and 59.0% at 6 months; and 42.9% and 62.9% at 12 months. ApoE gene polymorphism showed no statistical difference in ApoE allele or ApoE genotype between the control and the study groups. The effect of ApoE genotype on serum lipid levels was different between controls and recipients either before or after renal transplantation. The levels of serum TC, TG, low-density lipoprotein cholesterol, ApoB, ApoE were: (ε)2/2+(ε)2/3; (ε)3/3; (ε)3/4+(ε)4/4 from low to high in controls and recipients before transplantation, but the levels of TG and ApoE reversed among recipients after renal transplantation.

CONCLUSION

Renal transplant recipients are liable to develop hyperlipidemia, particularly hypertriglyceridemia among recipients with ApoE genotypes (ε)2/2 or (ε)2/3.

Impact of Lipoprotein Glomerulopathy on the Relationship Between Lipids and Renal Diseases

Lipoprotein glomerulopathy (LPG) is a unique entity of renal lipidosis characterized by peculiar histopathologic characteristics of lipoprotein thrombi and an abnormal plasma lipoprotein profile resembling type III hyperlipoproteinemia, with a marked increase in serum apolipoprotein E (apoE) concentrations. At present, 65 cases have been reported worldwide, although most patients are found in Japan and east Asian countries. Recently, we identified 4 types of novel apoE mutations associated with LPG. In particular, a mutation designated apoE Sendai, in which arginine 145 is substituted with proline, occurs in the majority of Japanese patients. The virus-mediated transduction of apoE Sendai resulting in the development of LPG in apoE-deficient mice confirms the etiologic role of apoE mutation in LPG. Conversely, experimental graft-versus-host disease induced in Fc receptor gamma-chain-deficient mice showed LPG-like lesions in glomeruli without apoE mutations. Considered together, we believe that intrinsic factors in the kidney also contribute to the induction of LPG. Today, apoE and related lipid abnormalities are reported to have an important role in the development of various renal diseases, eg, diabetic nephropathy and immunoglobulin A nephropathy. In this article, we review clinical and histopathologic features of LPG, describe the etiologic role of apoE variants and intrinsic renal factors, and discuss the impact of LPG on mechanisms of other renal diseases.

Influence of apolipoprotein E genotype on progression of diabetic nephropathy

AIMS

Diabetic nephropathy progresses at a variable rate part of which may be explained by genetic polymorphisms. ApoE polymorphisms are associated with progression of atherosclerosis and because of the similarities between atherosclerosis and glomerulosclerosis, we chose to examine apoE and its role in progression of diabetic nephropathy.

METHODS

The apoE genotypes of 90 patients with type 2 diabetes and nephropathy who were recruited into a 2-year prospective randomised controlled study comparing intensive medical management with routine clinical care were analysed. The primary endpoint was the rate of progression of renal disease in the second year.

RESULTS

The apoE genotype frequencies were 49 with E3/3, 20 with E2/3, 17 with E3/4 and 4 with of E2/4. There were no significant differences in age, degree of renal failure, BP, albuminuria or glycaemic control between any genotype. The rate of progression of renal failure of patients with the E3/4 genotype was 0.80 ml/min/month compared to 0.30 ml/min/month for E2/3 and 0.18 ml/min/month for those with E3/3. Patients with E3/4 genotype had significantly faster rates of progression in the second year when compared with the other 3 genotypes (0.80 vs. 0.25 ml/min/month, p = 0.012). There was no difference in mortality according to apoE genotype.

CONCLUSION

Patients who possess the apoE3/4 genotype had significantly faster rates of progression of renal failure.

Apolipoprotein E gene polymorphism in renal transplant recipients: effects on lipid metabolism, atherosclerosis and allograft function

INTRODUCTION

Atherosclerosis is a serious complication and leading cause of mortality in renal transplant recipients (RTRs). Hyperlipidemia may be associated with progression of renal disease and chronic allograft dysfunction. Similarities in the pathogenesis of glomerulosclerosis and atherosclerosis have been proposed. Apolipoprotein (apo) E gene code forms three major isoforms (E2, E3, and E4) with variable effects on lipid metabolism.

PATIENTS AND METHODS

A total of 118 patients, at a mean age of 40 +/- 8 yr, were included in the study. Apo E genotyping was carried out on genomic DNA using polymerase chain reaction and restriction enzyme. Carotid artery intima media thickness and atherosclerotic plaques were evaluated by B-mode ultrasonography. The plasma levels of lipids and lipoproteins and acute phase reactants were also studied. Allograft function was evaluated by measuring serum creatinine and creatinine clearance values.

RESULTS

The frequencies of E2, E3, and E4 alleles were 0.10, 0.78, and 0.12 respectively. Carotid artery atherosclerosis was found in 25% of E2 carriers, 30% of E3 carriers, and 57% of E4 carriers. Total cholesterol, total triglyceride, low-density lipoprotein, very low-density lipoprotein, apo B 100 levels were found to be higher in apo E4 carriers. Median apo A1 level was higher and allograft functions were better in apo E2 carriers (p < 0.05). Multiple regression analysis showed that allograft functions were negatively correlated with elevated acute phase reactants (p < 0.01) and only the age, but not the apo E genotypes, was an independent risk factor for atherosclerotic vascular disease (p < 0.01).

DISCUSSION

The pathogenetic events linking lipid metabolism and allograft functions and development of atherosclerosis are complex and multifactorial in RTRs. Our results showed that apo E genotypes have influences on lipids, lipoproteins and allograft functions. The ultimate role of apo E4 gene polymorphism as a risk factor for development and progression of atherosclerosis in RTRs should be sought in further studies.

Influence of apolipoprotein E polymorphisms on serum creatinine levels and predicted glomerular filtration rate in healthy subjects

BACKGROUND

There are conflicting results regarding the effect of apolipoprotein (ApoE) polymorphisms on the progression of a variety of renal diseases. However, there are no data on the possible effect of the ApoE alleles on serum creatinine levels and predicted glomerular filtration rate (GFR) in healthy subjects.

METHODS

290 apparently healthy individuals were studied. ApoE genotyping was performed by the polymerase chain reaction; the Modification of Diet in Renal Disease equation (MDRD) predicted the GFR.

RESULTS

ApoE2 was associated with lower levels of total cholesterol, low-density lipoprotein cholesterol and non-high-density lipoprotein cholesterol, as well as with higher levels of triglycerides in our population. Furthermore, the ApoE2 allele was associated with increased serum creatinine levels compared with both the E3 and E4 alleles (1.04+/-0.13 vs 0.92+/-0.13 vs 0.88+/- 0.11 mg/dl, respectively, P = 0.0077), while the MDRD-predicted GFR was decreased in ApoE2 carriers compared with both E3 and E4 carriers (80.3+/-10.2 vs 88.1+/-9.6 vs 89.3+/-9.7 ml/min/1.73 m(2), respectively, P = 0.031). These observations remained significant statistically even if the effect of ApoE polymorphisms on age- and body-mass index-adjusted serum creatinine and MDRD-predicted GFR was separately analysed in both men and women. Although, ApoE4 carriers tended to exhibit lower levels of serum creatinine and higher values of predicted GFR compared with the E3 carries, these differences did not reach statistical significance.

CONCLUSIONS

ApoE2 allele seems to be associated with increased serum creatinine levels and decreased MDRD-predicted GFR in healthy subjects.

Apolipoprotein E and renal disease

Apolipoprotein E (ApoE) is a major constituent of plasma lipoproteins with many biological actions of great significance. Beyond the known influence of ApoE polymorphisms on serum lipid profile, the pathogenesis of atherosclerosis, and the development of neurodegenerative disorders, ApoE also has a major role in the pathogenesis and progression of a variety of renal diseases, as well as in the atherosclerotic complications associated with them. Briefly, the polymorphisms of ApoE are major determinants of plasma lipid levels in uremic patients. They may affect the risk for cardiovascular disease in this population, predispose to the development of diabetic nephropathy, influence the severity of certain glomerulopathies, and regulate mesangial and glomerular functions locally in the kidney microenvironment. Finally, certain mutations of the ApoE gene are associated with a recently described nephropathy, termed lipoprotein glomerulopathy.

Apolipoprotein C-III and E polymorphisms and cardiovascular syndrome, hyperlipidemia, and insulin resistance in renal transplantation

Hyperlipidemia and insulin resistance frequently develop after renal transplantation, contributing to cardiovascular disease. Individual differences in response based upon genetic variations in proteins regulating lipidic and glucose tolerance metabolism could be expected. In the general population, the S2 allelic variant of the apoprotein (apo) C-III gene has been associated with hypertriglyceridemia and an insulin resistant state, whereas the E4 allele of the apo E has been associated with hypercholesterolemia and atherosclerosis. Its influence in renal transplant patients remains to be seen. In order to assess the impact of apo E and C-III major polymorphisms on atherosclerotic vascular disease, lipid profile and impaired glucose tolerance in renal transplant patients, we studied 110 consecutively examined patients undergoing kidney transplantation (age range 24-73 years). Atherosclerotic complications were detected in 25% of patients, with age, male sex and hypercholesterolemia being significant atherosclerotic risk factors. Among the male patients with E4 allele, the odds ratio for coronary disease and global atherosclerosis were 10.2 (95% CI) and 6.4 (95% CI), respectively. There were no significant differences in the frequency of any of the polymorphisms among patients with dyslipidemia and impaired glucose tolerance. As the number of patients in our sample was small, larger studies are needed to verify these issues. While in the studied population C-III polymorphism appears to have little association with the prevalence of atherosclerotic complications, E4 allele should be considered as a genetic marker of coronary artery disease and global atherosclerosis in renal transplant patients.