Apolipoprotein E polymorphism in Vietnamese children and its relationship to plasma lipid and lipoprotein levels

Mechanisms and risk factors of metabolic syndrome in children and adolescents

Metabolic syndrome (MetS) is a complex disorder characterized by abdominal obesity, elevated blood pressure, hyperlipidemia, and elevated fasting blood glucose levels. The diagnostic criteria for MetS in adults are well-established, but there is currently no consensus on the definition in children and adolescents. The etiology of MetS is believed to involve a complex interplay between genetic predisposition and environmental factors. While genetic predisposition explains only a small part of MetS pathogenesis, modifiable environmental risk factors play a significant role. Factors such as maternal weight during pregnancy, children's lifestyle, sedentariness, high-fat diet, fructose and branched-chain amino acid consumption, vitamin D deficiency, and sleep disturbances contribute to the development of MetS. Early identification and treatment of MetS in children and adolescents is crucial to prevent the development of chronic diseases later in life. In this review we discuss the latest research on factors contributing to the pathogenesis of MetS in children, focusing on non-modifiable and modifiable risk factors, including genetics, dysbiosis and chronic low-grade inflammation.

Metabolic syndrome in a sample of Egyptian adolescent girls and its association with apolipoprotein E

AIM

Obesity and its metabolic complications are increasing in childhood and extend to adulthood. The aims of this study were to assess the prevalence of metabolic syndrome (MS) in a sample of Egyptian adolescent girls and investigate its association with apolipoprotein E.

METHODS

A cross-sectional study design was used, including 200 Egyptian adolescent girls aged between 12 and 18 years. They were subjected to blood pressure (BP) measurement, anthropometric measurements (weight, height and waist circumference (WC)), laboratory investigations (fasting glucose and lipid profile) and molecular analysis (Apo E).

RESULTS

Overweight/obese girls were suffering significantly, more than normal-weight girls, from hypertension (66.7 vs. 40.8%), diabetes diagnosed by elevated fasting blood glucose (46.7 vs. 31.2%) and low high-density lipoprotein (HDL) (64 vs. 59.2%). Girls with MS had significantly higher values of body mass index Z-score, WC, BP, cholesterol and triglycerides and significantly lower HDL. Allele E3 (59.1 vs. 55.1%) was more frequent among girls with MS, while allele E4 (41 vs. 36.4) was more frequent among girls without MS. MS was the most prominent among girls with the E3/E4 genotype (35.7%), who had the highest frequency of elevated cholesterol, triglycerides, low-density lipoprotein and blood glucose, while girls with the E2/E4 genotype, which was rare among both groups, had the highest frequency of elevated BP (68.8%) and low HDL (71.4%).

CONCLUSION

MS was significantly more prominent among overweight/obese adolescent girls with the E3/E4 genotype, who had the highest frequency of disturbed lipid profile and blood glucose.

Analysis of apolipoprotein E genetic polymorphism in a large ethnic Hakka population in southern China

There is currently no data about the genetic variations of APOE in Hakka population in China. The aim of this study was to analyze the allelic and genotypic frequencies of APOE gene polymorphisms in a large ethnic Hakka population in southern China. The APOE genes of 6,907 subjects were genotyped by the gene chip platform. The allele and genotype frequencies were analyzed. Results showed that the ∊3 allele had the greatest frequency (0.804) followed by ∊2 (0.102), and ∊4 (0.094), while genotype ∊3/∊3 accounted for 65.43% followed by ∊2/∊3 (15.85%), ∊3/∊4 (14.13%), ∊2/∊4 (3.01%), ∊4/∊4 (0.84%), and ∊2/∊2 (0.74%) in all subjects. The frequencies of the ∊4 allele in Chinese populations were lower than Mongolian and Javanese, while the frequencies of the ∊2 allele were higher and ∊4 allele lower than Japanese, Koreans, and Iranian compared with the geographically neighboring countries. The frequencies of ∊2 and ∊4 alleles in Hakka population were similar to the Vietnamese, Chinese-Shanghai, Chinese-Kunming Han and Chinese-Northeast, and French. The frequency of ∊2 in Hakka population was higher than Chinese-Dehong Dai and Chinese-Jinangsu Han. The low frequency of the APOE ∊4 allele may suggest a low genetic risk of Hakka population for cardiovascular disease, Alzheimer's disease, and other diseases.

Analysis of SLCO1B1 and APOE genetic polymorphisms in a large ethnic Hakka population in southern China

OBJECTIVE

Statins are the most widely used lipid-lowering drugs, which have a significant effect on the inhibition of cardiovascular disease. The efficacy and side effects of statins are associated with the polymorphisms of SLCO1B1 and APOE genes. The purpose of this study was to analyze the SLCO1B1 and APOE gene polymorphisms in the Hakka population of southern China.

METHODS

A total of 3249 subjects including 2019 males and 1230 females participated in this study. Polymerase chain reaction (PCR)-fluorescence probe technique for polymorphisms analysis and analyzed the genotypes frequencies of SLCO1B1 and APOE genes.

RESULTS

The frequencies of SLCO1B1 521T>C between men and women were statistically significant (SLCO1B1 521TT, χ2  = 8.431, P = .004; SLCO1B1 521TC, χ2  = 7.436, P = .007). The frequencies of haplotypes *1b/*1b (40.07%) and *1a/*1b (32.56%) of SLCO1B1 gene accounted for 72.63%, followed by *1b/*15(14.40%), *1a/*1a (5.82%), *1a/*15 (5.57%), *15/*15 (1.45%), and *1a/*5 (0.12%). The frequencies of haplotypes *1a/*15 and *1b/*1b of SLCO1B1 gene between men and women were statistically significant (*1a/*15, χ2  = 6.789, P = .009; *1b/*1b, χ2  = 3.998, P = .004). In this study, genotype ɛ3/ɛ3 accounted for 69.04%, followed by ɛ3/ɛ4 (16.19%), ɛ2/ɛ3 (11.60%), ɛ2/ɛ4 (1.35%), ɛ4/ɛ4 (1.08%), and ɛ2/ɛ2 (0.74%) in all subjects, in which ɛ3 had the greatest allele frequency (82.93%), followed by ɛ4 (9.85%) and ɛ2 (7.22%). We found that 47 subjects carrying the SLCO1B1 521 (CC) polymorphism who had not any myopathy caused by statins.

CONCLUSIONS

We analyzed the SLCO1B1 and APOE gene polymorphisms in the Hakka population of southern China. This study provides a reference for the individualized meditation for Hakka population in this area.

Association of apolipoprotein E polymorphism with plasma lipid disorders, independent of obesity-related traits in Vietnamese children

Background

The dyslipidemia associated with obesity plays a major role in the development of atherosclerosis and cardiovascular disease. Dyslipidemia in childhood can progress in adult stage. APOE is one of the most important genes that regulate plasma lipid transport and clearance. The study aimed to assess whether the common APOE polymorphism is associated with lipid profiles and dyslipidemia, and it could be modulated by obesity-related traits (body mass index, waist circumference, hip circumference, and waist-to-hip ratio) in Vietnamese children.

Methods

A case-control study was designed including 249 cases with dyslipidemia and 600 controls without dyslipidemia. Dyslipidemia is defined as elevated total or low-density lipoprotein (LDL) cholesterol levels, or low levels of high-density lipoprotein (HDL) cholesterol. Genotype for APOE polymorphism (rs7412 and rs429358) was determined by the polymerase chain reaction and restriction fragment length polymorphism method. The association of APOE genotypes with plasma lipid disorders was tested by binary logistic regression analysis, taking into account the confounding factors of age, sex, residence, province and obesity-related traits.

Results

In comparison with ε3/ε3 carriers, the ε4 carriers had the highest concentration of serum TC and LDL-C in cases and controls (P ≤ 0.001), while ε2 carriers had the lowest. Carriers without TT haplotype had higher serum TC than those with TT haplotype. The ε4 carriers had higher hypoalphalipoproteinemia risk than ε3/ε3 carriers (OR = 2.78, P = 0.02) before and after adjustment for age, gender, residence and obesity-related traits.

Conclusions

The study suggested that the APOE genotype and haplotype significantly associated with plasma TC and LDL-C level in Vietnamese children. The association of APOE genotype with hypoalphalipoproteinemia was independent of obesity-related traits.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-016-0349-6) contains supplementary material, which is available to authorized users.

Factors Associated with Changes in Brain Atrophy during a Three-Year Observation in Elderly Diabetic Patients: Effect of Renal Impairment on Hippocampal Atrophy

BACKGROUND/AIMS

We conducted a 3-year longitudinal study concerning factors associated with changes in brain atrophy in elderly diabetic patients.

METHODS

We evaluated hippocampal and global brain atrophy using automatic voxel-based morphometry of structural magnetic resonance images, 4 cognitive function tests, and cerebral small vessel disease (SVD) in 66 diabetic patients.

RESULTS

During the 3-year follow-up, hippocampal and global brain atrophy advanced, and cognitive functions worsened. For changes in hippocampal atrophy, changes in estimated glomerular filtration rate (eGFR), albuminuria, and being an ApoE ε4 carrier were independent factors; change in the number of silent brain infarctions was an independent factor for changes in global brain atrophy. A significant association of changes in eGFR and albuminuria with hippocampal atrophy remained after adjusting for confounders including SVD. Both types of brain atrophy at baseline were significantly correlated with cognitive impairment at baseline and especially associated with changes in delayed word recall during the follow-up after adjusting for confounders.

CONCLUSION

Changes in eGFR and albuminuria during follow-up were independent risk factors for hippocampal atrophy, which was associated with decline in delayed word recall, suggesting that management of chronic kidney disease may prevent the progression of hippocampal atrophy.

Aerobic fitness modulates the association between APOE genotypes and serum lipemia in adolescents

The purpose of this study was to analyze the association between APOE alleles and serum lipemia in adolescents with low and adequate aerobic fitness. The sample was comprised of 105 boys and 151 girls (49% and 46% from rural area) of European ancestry, aged 11 to 17 years, and classified according to: 1) APOE genotype: group ε2 (ε2/3+ε2/2), ε3 (ε3/3), and ε4 (ε3/4+ε4/4); 2) aerobic fitness: adequate or low; 3) serum lipemia: elevated total cholesterol (TC), low-density lipoprotein (LDL) and triglycerides, and low high-density lipoprotein (HDL). The results showed that aerobic fitness modulates the association between APOE alleles and serum lipemia in adolescents, suggesting that adequate aerobic fitness levels exert a greater effect of reducing TC and LDL in ε2 carriers, as well as of increasing HDL and reducing triglycerides in ε3 and ε4 carriers.

Genetic influences on blood lipids and cardiovascular disease risk: tools for primary prevention

Genetic polymorphism in human populations is part of the evolutionary process that results from the interaction between the environment and the human genome. Recent changes in diet have upset this equilibrium, potentially influencing the risk of most common morbidities such as cardiovascular diseases, obesity, diabetes, and cancer. Reduction of these conditions is a major public health concern, and such a reduction could be achieved by improving our ability to detect disease predisposition early in life and by providing more personalized behavioral recommendations for successful primary prevention. In terms of cardiovascular diseases, polymorphisms at multiple genes have been associated with differential effects in terms of lipid metabolism; however, the connection with cardiovascular disease has been more elusive, and considerable heterogeneity exists among studies regarding the predictive value of genetic markers. This may be because of experimental limitations, the intrinsic complexity of the phenotypes, and the aforementioned interactions with environmental factors. The integration of genetic and environmental complexity into current and future research will drive the field toward the implementation of clinical tools aimed at providing dietary advice optimized for the individual's genome. This may imply that dietary changes are implemented early in life to gain maximum benefit. However, it is important to highlight that most reported studies have focused on adult populations and to extrapolate these findings to children and adolescents may not be justified until proper studies have been carried out in these populations and until the ethical and legal issues associated with this new field are adequately addressed.

Genetic variation of apolipoprotein E does not contribute to the lipid abnormalities secondary to childhood minimal change nephrotic syndrome

Minimal change nephrotic syndrome (MCNS) is a common progressive renal disorder occurring in childhood that is characterized by alterations of permselectivity at the glomerular capillary wall, resulting in its inability to restrict the urinary loss of protein. Hyperlipidemia (HLP) is not only an important clinical manifestation of MCNS but is also involved in cardiovascular disease and in progressive renal damage. ApoE is a polymorphic protein. Besides modulation of lipid metabolism, apoE can also elevate the sulfate-proteoglycan in glomerular filtration membrane and inhibit the proliferation of mesengial cells. The present study aimed mainly to determine whether genetic polymorphism of apoE is involved in the HLP secondary to childhood MCNS. Genomic DNA was extracted from 250 children diagnosed with MCNS and 200 healthy controls. ApoE genotype was determined by PCR-restriction fragment length polymorphism (RFLP) analysis. The fasting serum lipoprotein (a) [Lp(a)], total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A1 (apoA1), and apoB were measured. Serum concentrations of Lp(a), TC, TG, HDL-C, nonHDL-C, LDL-C, and apoB were higher in the MCNS than in the control group (P < 0.05). No significant differences in genotypes and alleles frequencies were observed for the apoE Hha I restriction sites in MCNS patients as compared to controls (P > 0.05). No significant differences in serum lipid levels were observed for variant genotypes and alleles of apoE Hha I restriction site in both MCNS and healthy children (P > 0.05). Genetic variation of apoE does not contribute to the lipid abnormalities secondary to childhood MCNS.

Association between apolipoprotein E polymorphism, lipids, and coronary artery disease in Tunisian type 2 diabetes

BACKGROUND

The relationship between apolipoprotein E (ApoE) polymorphism, fasting lipid parameters, and coronary artery disease (CAD) is controversial.

METHODS

We studied this relationship, for the first time, in Tunisian type 2 diabetic patients. The studied population comprised 157 type 2 diabetic patients (145 of them were not on any lipid-lowering drugs). Fasting lipids were measured by enzymatic methods and ApoE genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Our results showed that the alleles E2, E3, and E4 were found in 4%, 88%, and 8% of patients, respectively. In the total type 2 diabetic population, no association was found between ApoE polymorphism, lipid parameters, and CAD. However, the E4 allele was associated with elevated low-density lipoprotein cholesterol concentration and with CAD in type 2 diabetic men.

CONCLUSION

The effect of ApoE polymorphism on CAD is gender-dependent in the Tunisian type 2 diabetic population. ApoE 4 allele may enhance atherogenesis indirectly by a strong effect on low-density lipoprotein cholesterol.

Association of polymorphisms at restriction enzyme recognition sites of apolipoprotein B and E gene with dyslipidemia in children undergoing primary nephrotic syndrome

BACKGROUND

Dyslipidemia, a common complication, is very prevalent in children with primary nephrotic syndrome (PNS). Recent studies have shown that genetic basis may be involved in the onset of HLP secondary to PNS. ApoB and E have been identified as the important candidate genes for lipid abnormalities.

OBJECTIVE

To investigate the association of apolipoprotein B (apoB) and E (apoE) genetic polymorphisms (Xba I, EcoR I, Msp I, and Hha I) with parameters describing the serum lipid profiles in children undergoing PNS.

METHODS

Genomic DNA was extracted from 250 children diagnosed with PNS and 200 healthy controls with neither allergic nor renal disease. ApoB (Xba I, EcoR I, and Msp I) and apoE (Hha I) genotypes were determined by PCR-restriction fragment length polymorphism (RFLP) analysis. The fasting serum lipoprotein (a) [Lp(a)], total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), apolipoprotein A1 (apoA1), apoB, and total protein from a 24-h urine sample were measured.

RESULTS

No significant differences in genotypes and alleles frequencies were observed for the apoB Xba I, EcoR I, Msp I and the apoE Hha I restriction sites in PNS patients as compared to controls (P > 0.05). Patients and controls with X + allele exhibited significantly higher serum levels of Lp(a), TC, nonHDL-C, LDL-C, LDL-C/HDL-C ratio, and apoB than that with X- allele (P < 0.05), whereas for apoA1/B ratio the opposite was found (P < 0.01). E-/E- carriers had significantly higher Lp(a), TC, HDL-C, and apoA1 concentrations than did E+/E- or E+/E+ carriers in control group (P < 0.05). Healthy children carrying the rare EcoR I allele had higher mean Lp(a), TC, and HDL-C levels than homozygotes for E+ (P < 0.05). Higher Lp(a) serum concentrations were observed in patients with E- allele (P < 0.05). No significant differences in lipid parameters were determined for the apoB Msp I and apoE Hha I the polymorphisms study (P > 0.05). When genetic variations were compared with urinary protein excretion, the Xba I X- allele was more frequent in patients with elevated proteinuria (P < 0.01).

CONCLUSION

Presence of Xba I X+ allele and/or EcoR I E- at the apoB gene may be risk factors for lipid abnormalities secondary to childhood PNS.

Genetic determinants of plasma lipoproteins

The search for common genetic determinants of plasma lipoproteins began in the early 1980s. Despite some exceptions, these efforts have not yet yielded a set of biological markers that can be used in clinical practice. By contrast, successes in defining the molecular basis of rare single-gene disorders, such as familial hypoalphalipoproteinemia, have shown the value of experimental designs that focus on genomic analysis of individuals within the tails of Gaussian distributions of quantitative lipoprotein traits. For example, this strategy showed that a small but relevant proportion of individuals within the <5% tail of plasma HDL-cholesterol distribution have mutations in genes that cause familial hypoalphalipoproteinemia. The value of clinical testing for genomic variants as an adjunct to a biochemical measurement of plasma lipoproteins, however, is at best questionable. A more direct impact of genetic studies is that definitions of 'common' and 'large genetic effects' have become more tempered, reflecting perhaps the biological reality that plasma lipoproteins are probably determined by the aggregate of numerous modest and occasional large genetic effects in addition to environmental factors. Here, we review recent progress on genomic variants and cholesterol metabolism, and discuss the impact these genetic studies will have on clinical cardiology.

Genetic factors affecting HDL levels, structure, metabolism and function

PURPOSE OF REVIEW

HDL is a recognized negative risk factor for the cardiovascular diseases. Establishing the genetic determinants of HDL concentration and functions would add to the prediction of cardiovascular risk and point to the biochemical mechanisms underlying this risk. The present review focuses on various approaches to establish genetic determinants of the HDL concentration, structure and function.

RECENT FINDINGS

While many genes contribute to the HDL concentration and collectively account for half of the variability, polymorphism of individual candidate genes contributes little. There are strong interactions between environmental and genetic influences. Recent findings have confirmed that APOA1 and ABCA1 exert the strongest influence on HDL concentrations and risk of atherosclerosis. CETP and lipases also affect the HDL concentration and functionality, but their connection to the atherosclerosis risk is conditional on the interaction between environmental and genetic factors.

SUMMARY

Analysis of genetic determinants of HDL-cholesterol in patients with specific disease states or in response to the environmental condition may be a more accurate way to assess variations in HDL concentration. This may result in defining the rules of interaction between genetic and environmental factors and lead to understanding the mechanisms responsible for the variations in HDL concentration and functionality.

Linkage analysis of LDL cholesterol in American Indian populations: the Strong Heart Family Study

Previous studies have demonstrated that low density lipoprotein cholesterol (LDL-C) concentration is influenced by both genes and environment. Although rare genetic variants associated with Mendelian causes of increased LDL-C are known, only one common genetic variant has been identified, the apolipoprotein E gene (APOE). In an attempt to localize quantitative trait loci (QTLs) influencing LDL-C, we conducted a genome-wide linkage scan of LDL-C in participants of the Strong Heart Family Study (SHFS). Nine hundred eighty men and women, age 18 years or older, in 32 extended families at three centers (in Arizona, Oklahoma, and North and South Dakota) were phenotyped for LDL-C concentration and other risk factors. Using a variance component approach and the program SOLAR, and after accounting for the effects of covariates, we detected a QTL influencing LDL-C on chromosome 19, nearest marker D19S888 at 19q13.41 [logarithm of odds (LOD) = 4.3] in the sample from the Dakotas. This region on chromosome 19 includes many possible candidate genes, including the APOE/C1/C4/C2 gene cluster. In follow-up association analyses, no significant evidence for an association was detected with the APOE*2 and APOE*4 alleles (P = 0.76 and P = 0.53, respectively). Suggestive evidence of linkage to LDL-C was detected on chromosomes 3q, 4q, 7p, 9q, 10p, 14q, and 17q. These linkage signals overlap positive findings for lipid-related traits and harbor plausible candidate genes for LDL-C.