Apolipoprotein E phenotypes in Finnish youths: a cross-sectional and 6-year follow-up study

Genetic and molecular biomarkers for geographic atrophy

Geographic atrophy (GA) is characterized by atrophy of the retina, retinal pigment epithelium and choriocapillaris, causing a gradual loss of vision over time. Treatment options to prevent initiation or progression of GA are limited; two recently FDA-approved inhibitors of the complement system (pegcetacoplan, avacincaptad pegol) showed a modest decrease in GA lesion growth in phase 3 clinical trials. Exploration of genetic and molecular biomarkers in GA plays a critical role in our battle against this blinding disease to improve early disease detection, to find more effective therapies, and to provide personalized care to patients. In this review, we provide a comprehensive overview of the current literature investigating genetic and molecular biomarkers for GA. Genetic studies identified multiple genes and variants that play a role in progression to GA and GA lesion growth, involving pathways such as complement activation, extracellular matrix interaction and lipid metabolism. The number of published studies assessing molecular biomarkers for GA initiation and progression in ocular matrices is limited. Several studies evaluated molecular biomarkers in the systemic circulation, showing higher levels of complement activation and a causal role of lipid subfractions in GA. Larger, well-powered studies are needed to identify novel and validate existing biomarkers, and to investigate the potential of combining genetic and molecular markers with imaging techniques for more accurate diagnosis and monitoring of GA. The development of personalized medicine approaches based on individual genetic and molecular profiles could hold promise for more effective and targeted treatments for this devastating disease.

APOE alleles modulate associations of plasma metabolites with variants from multiple genes on chromosome 19q13.3

The APOE ε2, ε3, and ε4 alleles differentially impact various complex diseases and traits. We examined whether these alleles modulated associations of 94 single-nucleotide polymorphisms (SNPs) harbored by 26 genes in 19q13.3 region with 217 plasma metabolites using Framingham Heart Study data. The analyses were performed in the E2 (ε2ε2 or ε2ε3 genotype), E3 (ε3ε3 genotype), and E4 (ε3ε4 or ε4ε4 genotype) groups separately. We identified 31, 17, and 22 polymorphism-metabolite associations in the E2, E3, and E4 groups, respectively, at a false discovery rate P FDR < 0.05. These entailed 51 and 19 associations with 20 lipid and 12 polar analytes. Contrasting the effect sizes between the analyzed groups showed 20 associations with group-specific effects at Bonferroni-adjusted P < 7.14E-04. Three associations with glutamic acid or dimethylglycine had significantly larger effects in the E2 than E3 group and 12 associations with triacylglycerol 56:5, lysophosphatidylethanolamines 16:0, 18:0, 20:4, or phosphatidylcholine 38:6 had significantly larger effects in the E2 than E4 group. Two associations with isocitrate or propionate and three associations with phosphatidylcholines 32:0, 32:1, or 34:0 had significantly larger effects in the E4 than E3 group. Nine of 70 SNP-metabolite associations identified in either E2, E3, or E4 groups attained P FDR < 0.05 in the pooled sample of these groups. However, none of them were among the 20 group-specific associations. Consistent with the evolutionary history of the APOE alleles, plasma metabolites showed higher APOE-cluster-related variations in the E4 than E2 and E3 groups. Pathway enrichment mainly highlighted lipids and amino acids metabolism and citrate cycle, which can be differentially impacted by the APOE alleles. These novel findings expand insights into the genetic heterogeneity of plasma metabolites and highlight the importance of the APOE-allele-stratified genetic analyses of the APOE-related diseases and traits.

Relationship Between the ApoE Gene Polymorphism and Type 2 Diabetes Mellitus Complications

Background: Apolipoprotein E (ApoE) polymorphisms are associated with type 2 diabetes mellitus (T2DM) and its complications, but studies have shown conflicting results. Objective: To examine the relationship of ApoE gene polymorphisms with T2DM and its complications. Materials and Methods: This case-control study of patients with T2DM was conducted between June 2016 and July 2019. Healthy individuals were recruited as controls. The patients were grouped according to coronary heart disease (CHD), cerebral infarction (CI), diabetic nephropathy (DN), and neurological complications. The ApoE genotype was determined using a commercial gene chip. Results: Compared with controls, the frequencies of genotype ɛ3/4 (20.8% vs. 11.7%, p = 0.04) and allele ɛ4 (14.3% vs. 8.3%, p = 0.03) of patients with T2DM were higher. The frequency of genotype ɛ3/4 was higher in the T2DM with CHD group (30.4% vs. 17.4%, p = 0.01 vs. non-CHD) and in T2DM with CI (29.2% vs. 18.1%, p = 0.045 vs. non-CI). The frequency of genotype ɛ2/3 was higher in the T2DM with DN group (19.3% vs. 9.1%, p = 0.01 vs. non-DN). There were no significant differences between T2DM with and without neuropathy (p > 0.05). Conclusion: The ApoE allele ɛ4 may be a risk factor for T2DM, CHD in T2DM, and CI in T2DM, while the ApoE allele ɛ2 may be a risk factor for DN.

Putative Survival Advantages in Young Apolipoprotein ɛ4 Carriers are Associated with Increased Neural Stress

Inheritance of a single copy of the apolipoprotein E (APOE) ɛ4 allele increases risk of Alzheimer’s disease (AD) by 3-4-fold, with homozygosity associated with a 12-16-fold increase in risk, relative to ɛ3 allele homozygosity. There is a decreased risk associated with the APOE ɛ2 allele. The pathological consequence of APOE genotype has led to intense efforts to understand the mechanistic basis of the interplay between APOE status and loss of synapses. Numerous ɛ4 allele-related associations have been reported with the potential relevance of these associations to the pathogenesis of AD unknown at this time. In primarily young subjects, we have reviewed a representative body of literature on ɛ4 allele-associations related to the following: cardiovascular responses; impacts on reproduction and fetal development; co-morbidities; resistance to infectious disease; responses to head injury; biochemical differences possibly related to neural stress; and brain structure-function differences. In addition, the literature on the association between the ɛ4 allele and cognitive performance has been reviewed comprehensively. The weight-of-the-evidence supports the hypothesis that possession of the ancestral ɛ4 allele in youth is associated with improved fitness during fetal development, infancy, and youth relative to the more recently appearing ɛ3 allele, at the expense of decreased fitness in old age, which is substantially improved by the ɛ3 allele. However, possession of the ɛ4 allele is also associated with higher levels of synaptic macromolecular turnover, which likely stresses basic cellular neuroplasticity mechanisms. Clinical trials of potential AD therapeutics should consider APOE status as an enrollment criterion.

New evidence from plasma ceramides links apoE polymorphism to greater risk of coronary artery disease in Finnish adults

apoE, a key regulator of plasma lipids, mediates altered functionalities in lipoprotein metabolism and thus affects the risk of coronary artery disease (CAD). The significance of different apoE polymorphisms remains unclear; although the ε4 allele is clearly associated with increased cholesterol levels (which inform CAD risk), direct studies about apoE polymorphisms on CAD risk and development have yielded controversial results. Furthermore, certain species of ceramides-complex lipids abundant in plasma LDL-are markers of increased risk of myocardial infarction and cardiovascular death. Using a high-throughput MS approach, we quantified 30 molecular plasma ceramide species from a cohort of 2,160 apoE-genotyped (rs7412, rs429358) young adults enrolled in the population-based Cardiovascular Risk in Young Finns Study. We then searched this lipidome data set to identify new indications of pathways influenced by apoE polymorphisms and possibly related to CAD risk. This approach revealed a previously unreported association between apoE polymorphism and a consistently documented high-risk CAD marker, Cer(d18:1/16:0). Compared with the apoE ε3/3 reference group, plasma levels of apoE ε4 were elevated and those of apoE ε2 were lowered in all subjects without evidence of apoE-by-sex interactions. apoE associated with seven ceramides that are connected to atherogenically potent macrophages and/or lipoprotein particles; these associations could indicate a plausible linkage between apoE polymorphism and ceramide metabolism, leading to adverse plasma LDL metabolism and atherogenesis. In conclusion, new evidence from plasma ceramides links apoE polymorphism with an increased risk of CAD and extends our understanding of the role of apoE in health and disease.

Subtle Cognitive Impairment and Alzheimer's Disease-Type Pathological Changes in Cerebrospinal Fluid are Common Among Neurologically Healthy Subjects

BACKGROUND

The neuropathology of Alzheimer's disease (AD) has previously been shown to be rather common among the elderly.

OBJECTIVE

The aim of this study was to inspect the associations between cerebrospinal fluid (CSF) AD biomarker concentrations, age, the APOEɛ4 allele, cardiovascular diseases, diabetes, and cognitive performance in a cohort of a neurologically healthy population.

METHODS

This study included 93 subjects (42 men, mean age 67 years) without previous neurological symptoms or subjective cognitive complaints. Their cognition was assessed, and CSF biomarkers and APOEɛ4 status were analyzed.

RESULTS

Of the studied subjects, 8.6% (n = 8) had a pathological CSF AD biomarker profile. An increase in age correlated positively with CSF tau pathology and negatively with global cognitive performance.

CONCLUSION

AD-type pathological changes in CSF and subtle cognitive impairment are common within a population with no previous memory complaints. Age was the main risk factor for the changes.

The effect of apolipoprotein E polymorphism on serum metabolome - a population-based 10-year follow-up study

Apolipoprotein E (apoE) is the key regulator of plasma lipids, mediating altered functionalities in lipoprotein metabolism - affecting the risk of coronary artery (CAD) and Alzheimer's diseases, as well as longevity. Searching pathways influenced by apoE prior to adverse manifestations, we utilized a metabolome dataset of 228 nuclear-magnetic-resonance-measured serum parameters with a 10-year follow-up from the population-based Young Finns Study cohort of 2,234 apoE-genotyped (rs7412, rs429358) adults, aged 24-39 at baseline. At the end of our follow-up, by limiting FDR-corrected p < 0.05, regression analyses revealed 180/228 apoE-polymorphism-related associations with the studied metabolites, in all subjects - without indications of apoE x sex interactions. Across all measured apoE- and apoB-containing lipoproteins, ε4 allele had consistently atherogenic and ε2 protective effect on particle concentrations of free/esterified cholesterol, triglycerides, phospholipids and total lipids. As novel findings, ε4 associated with glycoprotein acetyls, LDL-diameter and isoleucine - all reported biomarkers of CAD-risk, inflammation, diabetes and total mortality. ApoE-subgroup differences persisted through our 10-year follow-up, although some variation of individual metabolite levels was noticed. In conclusion, apoE polymorphism associate with a complex metabolic change, including aberrations in multiple novel biomarkers related to elevated cardiometabolic and all-cause mortality risk, extending our understanding about the role of apoE in health and disease.

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.

Associations of Genetic Susceptibility to Alzheimer's Disease with Adiposity and Cardiometabolic Risk Factors among Children in a 2-Year Follow-up Study

We investigated the associations of genetic risk score (GRS) for Alzheimer's disease and apolipoprotein E (APOE) ɛ variant with cardiometabolic risk factors during 2-year follow-up in children and whether body fat percentage (BF%) modify these associations. A population-based sample of 469 children (246 boys, 223 girls) at baseline and 398 children (201 boys, 197 girls) at 2-year follow-up participated in the study. Genotyping was performed using the Illumina Custom Infinium CardioMetabo BeadChip and the Illumina Infinium HumanCoreExome BeadChip. The GRS was calculated using information on nine independent gene variants available in our genomic data. We assessed BF%, waist circumference, insulin, glucose, triglycerides, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, and systolic and diastolic blood pressure. We computed a cardiometabolic risk score and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). In boys, the GRS was not associated with cardiometabolic risk factors. In girls, GRS was directly associated with LDL cholesterol (β= 0.133, 95% CI = 0.002 to 0.262) at baseline and with a higher cardiometabolic risk score (β= 0.154, 95% CI = 0.015 to 0.294), glucose (β= 0.143, 95% CI = 0.003 to 0.284), and HOMA-IR (β= 0.141, 95% CI = 0.004 to 0.278) at 2-year follow-up. GRS was directly associated with a cardiometabolic risk score at baseline and 2-year follow-up among girls in the highest third of BF% at baseline, but not in other girls (p < 0.05 for interaction). Children with the APOEɛ3/3 genotype had higher LDL cholesterol at and 2-year follow-up than those with the APOEɛ2/3 genotype. In conclusion, GRS was associated with increased cardiometabolic risk in girls and especially those with higher BF%.

Influence of Apolipoprotein E on the Lipid Profile and Postprandial Triglyceride Levels in Brazilian Postmenopausal Women With Artery Disease

This study confirms the association of risk factors for coronary artery disease (CAD) and the apoE polymorphisms, specifically related to the APOE*4 allele, with coronary disease in postmenopausal women. Significantly altered values of the lipid profile were found in patients when compared with controls, independent of the presence of the APOE*4 allele. However, the controls showed higher high-density lipoprotein cholesterol (HDL-C) levels and reduced triglyceride (TG) levels, differing significantly from patients. In this case, the study of subgroups, considering the APOE*3/3 and APOE*3/4 genotypes, suggests that the APOE*4 allele is not implicated in the variations of the lipid profile of patients and determined an increase in the production levels of HDL-C and a reduction in TG highly benefiting the control group compared with APOE*3/3 genotype. The metabolic kinetics of TG, although with the same pattern between groups, and the presence of the APOE*4 allele are suggested to be associated with accelerated clearance compared with APOE*3 allele in non-CAD group.

Fuzzy set analyses of genetic determinants of health and disability status

Analyses of complex genotype-phenotype relations require new statistical procedures because of the potentially high dimensionability of those relations which are expressed with both measurement error and stochasticity in the correlation function. We propose modifying a multivariate procedure called grade of membership (GoM) analysis to deal with the special problems of such analyses. In doing so, we make clear some special features of the GoM model for multivariate analysis of high dimensional, discrete data. This is illustrated for apolipoprotein E (APOE) assessments made on 1805 people in the 1999 National Long Term Care Survey. A number of interesting relations with APOE polymorphism were found where disability profiles were more predictive than specific diagnoses because they implicitly contained information on chronicity and severity of disease processes.

Maternal apolipoprotein E genotype as a potential risk factor for poor birth outcomes: The Bogalusa Heart Study

OBJECTIVE

The objective of this study was to assess the association between apolipoprotein E (apoE) genotype and preterm birth (PTB) and small for gestational age (SGA).

STUDY DESIGN

ApoE phenotyping was performed on 680 women linked to 1065 births. Allele frequencies were compared and PTB and SGA risk was estimated using log-binomial regression.

RESULTS

The ɛ2 allele was more common in SGA births (P<0.01). SGA risk was increased among ɛ2 carriers compared with genotype ɛ3/ɛ3, though associations were attenuated following adjustment for maternal age, education, race, smoking and prenatal visits. Stronger associations were observed for term SGA (first birth: adjusted relative risk (aRR)=1.78, 95% confidence interval (CI) 1.06 to 2.98; any birth: aRR=1.52, 95% CI 0.96 to 2.40) and among whites specifically (first: aRR=2.88, 95% CI 1.45 to 5.69; any: aRR=2.75, 95% CI 1.46 to 5.22).

CONCLUSIONS

Associations between maternal apoE genotype and SGA may represent decreased fetal growth in women with lower circulating cholesterol levels.

Infant mortality and ethnicity in an indigenous European population: novel evidence from the Finnish population register

We provide the first analyses of infant mortality rates by indigenous ethnic group in Finland, a country that has one of the lowest relative numbers of infant deaths in the world. Using files from the Finnish population register, we identified both of the parents of children born in the period from 1975-2003 according to ethnic affiliation, socioeconomic profile, and demographic position. The infant mortality rate in homogamous Finnish unions is similar to that in homogamous Swedish unions, which reflects a lack of social disparities between the two groups. Surprisingly, infants from ethnically mixed unions have markedly lower mortality rates, with an adjusted rate ratio of 0.81 relative to homogamous Swedish unions (95% CI: 0.67-0.98). Although not empirically verified, we argue that the lower infant mortality rate in ethnically mixed unions may be due to lower levels of inbreeding, and hence related to historically low intermarriage rates between the two ethnic groups, remote consanguinities, and restricted inter-community gene flow.

New insights into the distribution of APOE polymorphism in the Iberian Peninsula. The case of Andalusia (Spain)

BACKGROUND

The APOE gene has received much attention due to the remarkable spatial variation patterns of some of its genotypes and alleles in human populations and to its relevance in biomedicine.

AIM

This work was addressed to investigate the extent of APOE polymorphism between autochthonous Andalusians originating from Huelva and Granada provinces. No data on this marker in these southern Spanish coastal populations are available up to date.

SUBJECTS AND METHODS

This study used genomic DNA from healthy, unrelated Andalusians of both sexes (n = 322). All samples were genotyped for two SNPs, rs429358 and rs7412, which determine the three APOE alleles: ε2, ε3 and ε4. For analyses, a TaqMan-based technique was applied using a RT-PCR. Comparisons with other Mediterranean populations were performed based on multivariate analysis.

RESULTS

A relatively high frequency of ε4 in Granada (eastern Andalusia), as well as a low ε2 frequency in Huelva (western Andalusia) were observed. The finding that ε4 allele in Southern Spain and Portugal is higher than expected given its geographical location poses an interesting question for this study, given the well-established APOE-ε4 gradient in Europe.

CONCLUSION

This population study may represent useful information for further prospective anthropological and molecular genetic studies focused on unravelling the relationship between population genetic composition and specific human diseases.

Age-dependent interaction of apolipoprotein E gene with eastern birthplace in Finland affects severity of coronary atherosclerosis and risk of fatal myocardial infarction--Helsinki Sudden Death Study

BACKGROUND

Mortality from coronary heart disease (CHD) has been constantly higher in eastern late settlement regions compared to western early settlements in Finland, unrelated to classical risk factors. In line with this, eastern birthplace was an age-dependent predictor of severe coronary atherosclerosis and pre-hospital sudden coronary death among male residents of Helsinki. We investigated a possible interaction of apolipoprotein E (APOE) gene with birthplace on the risk of myocardial infarction (MI) and coronary atherosclerosis.

METHOD

APOE genotypes were analyzed in the Helsinki Sudden Death Study series comprising out-of-hospital deaths among males aged 33-70 years (n = 577), who were born in high (east, n = 273) or low (west, n = 304) CHD mortality area.

RESULTS

Eastern-born men ≤ 55 years carried 30% more often (P = 0.017) and older men 40% less often (P = 0.022) the APOE ϵ4 allele compared to western-born men (P = 0.003 for birthplace-by-age interaction). In multivariate analysis, the ϵ4 allele associated with the risk of out-of-hospital MI (odds ratio 2.58; 95% CI 1.20-5.55; P = 0.016) only in eastern-born men and with advanced atherosclerosis in both regions of origin, respectively.

CONCLUSIONS

Birthplace-bound risk of CHD was age-dependently modified by APOE ϵ4 allele, suggesting genetic differences in CHD susceptibility between early and late settlement regions in Finland and providing one explanation for the eastern high mortality.

Pharmacogenetics of statins: achievements, whole-genome analyses and future perspectives

Statins are the most commonly prescribed class of drug worldwide and therapy is highly effective in reducing low-density lipoprotein cholesterol levels and cardiovascular events. However, there is large variability in clinical response to statin treatment. Recent research provides evidence that genetic variation contributes to this variable response to statin treatment. Until recently, pharmacogenetic studies have used mainly candidate gene approaches to investigate these effects. Since candidate gene studies explain only a small part of the observed variation and results have often been inconsistent, genome-wide association (GWA) studies may be a better approach. In this paper the most important candidate gene studies and the first published GWA studies assessing statin response are discussed. Moreover, we describe the PHASE study, an EU-funded GWA study that will investigate the genetic variation responsible for the variation in response to pravastatin in a large randomized clinical trial.

IQ, educational attainment, memory and plasma lipids: associations with apolipoprotein E genotype in 5995 children

BACKGROUND

Apolipoprotein E (APOE) genotype (ε2/ε3/ε4: rs429358 ε4 allele; rs7412 ε2 allele) is strongly associated with both lipid levels and Alzheimer's disease. Although there is also evidence of milder cognitive impairment in later life in carriers of the APOE ε4 allele, there have been few studies investigating the impact of APOE genotype on cognitive function in children.

METHODS

We determined APOE genotype in 5995 children from the Avon Longitudinal Study of Parents and Children and investigated associations between APOE genotype and plasma lipids (at age 9), IQ (at age 8), memory (at ages 8 and 10), and performance in school attainment tests (at ages 7, 11, and 14).

RESULTS

Observed genotype group counts were consistent with Hardy-Weinberg equilibrium (χ(2)p value = .84). There were strong relationships between APOE genotype and low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides, which follow the same patterns as in adults. There was no strong evidence to suggest that APOE genotype was associated with IQ (all p values ≥ .46), memory function (p ≥ .35), or school attainment test results (p ≥ .28).

CONCLUSION

Although APOE genotype does have strong associations with lipid levels in childhood, there does not seem to be meaningful effects on cognitive performance, suggesting that any detrimental effects of the ε4 allele on cognitive function are not important until later life.

The effects of apoA-I/C-III/A-IV, apoE and apoB polymorphisms on carotid artery intima-media thickness

Different apolipoprotein combinations explain most of the functional differences between plasma lipoproteins. This emphasizes the pivotal role of apolipoproteins in the homeostasis and physiological control of lipid metabolism. Genetic polymorphisms of apolipoprotein (apo)A-I/C-III/A-IV, apoE and apoB have been suggested to modulate plasma lipid levels as well as the risk of coronary artery disease and stroke. Carotid artery intima-media thickness has been shown to represent preclinical atherosclerosis and has, therefore, been used as a surrogate in quantifying the early stages of atherosclerosis. The effects of the polymorphisms in apoA-I/C-III/A-IV and apoB on carotid intima-media thickness are poorly known. The corresponding influence of apoE polymorphisms has been studied more extensively, but the results are not yet conclusive. In this review, these results are presented in detail and the potential reasons and mechanisms for the discrepancies are discussed.

Birthplace in area with high coronary heart disease mortality predicts the severity of coronary atherosclerosis among middle-aged Finnish men who had migrated to capital area: the Helsinki sudden death study

BACKGROUND

Reasons why eastern-born male Finns have higher coronary heart disease (CHD) mortality than do western-born men are still unsettled. Recently, eastern birthplace was found to be an independent predictor of pre-hospital sudden cardiac death (SCD) in the new low-mortality area of residence.

AIM

To investigate the association of birthplace with high CHD mortality attributes to more severe coronary atherosclerosis among men migrated to the low-mortality capital area.

METHOD

Coronary atherosclerosis was measured in 373 western-born and 314 eastern-born out-of-hospital male deaths aged 33-70 years in Helsinki (The Helsinki Sudden Death Study), covering 24.6% of male deaths within this age-group. CHD risk factors were obtained from an interview of a next of kin.

RESULTS

In multivariate analysis there was a strong birthplace-by-age interaction with atherosclerosis (P = 0.0005). Eastern-born men <54 years had larger areas of fatty streaks (P = 0.0195), fibrotic plaque (P = 0.0133), calcification (P = 0.0009), total plaque area (P = 0.0011), and greater stenosis (P = 0.0004) in the left coronary compared to western-born men, independent of CHD risk factors. Amongst older men (>or=54 years) such an association no longer appeared.

CONCLUSION

Higher CHD mortality among eastern-born men may be due to more severe coronary atherosclerosis independently of CHD risk factors, reflecting Finns' two-phase settlement history.

Apolipoprotein E genotype and hepatitis C, HIV and herpes simplex disease risk: a literature review

Apolipoprotein E is a polymorphic and multifunctional protein with numerous roles in lipoprotein metabolism. The three common isoforms apoE2, apoE3 and apoE4 show isoform-specific functional properties including different susceptibilities to diseases. ApoE4 is an accepted risk factor for Alzheimer's disease and cardiovascular disorders. Recently, associations between apoE4 and infectious diseases have been demonstrated. This review summarises how apoE4 may be involved in the infection incidence and associated pathologies of specific infectious diseases, namely hepatitis C, human immunodeficiency virus disease and herpes simplex.ApoE4 seems to be protective against chronic hepatitis C virus infection and retards fibrosis progression. In contrast apoE4 enhances the fusion rate of human immunodeficiency virus with target cell membranes, resulting in accelerated cell entry and faster disease progression. Its association with human immunodeficiency virus-associated dementia remains controversial. Regarding herpes simplex virus infection, apoE4 intensifies virus latency and is associated with increased oxidative damage of the central nervous system, and there is some evidence that herpes simplex virus infection in combination with the apoE4 genotype may be associated with an increased risk of Alzheimer's disease. In addition to reviewing available data from human trials, evidence derived from a variety of cell culture and animal models are considered in this review in order to provide mechanistic insights into observed association between apoE4 genotype and viral disease infection and pathology.

Carbohydrate intake, serum lipids and apolipoprotein E phenotype show association in children

AIM

To study the association between carbohydrate intake and serum lipids in children, and influence of apolipoprotein E phenotype (apoE) on the association.

SUBJECTS/METHODS

A total of 644 children from a prospective, randomized atherosclerosis prevention trial (STRIP) participated in this longitudinal study at age 5 (n = 644), 7 (n = 585) and 9 (n = 550) years. ApoE phenotype, fasting triglyceride, total, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol concentrations and 4-day food records were analysed.

RESULTS

An increase in the total carbohydrate intake by 1 E% (percentage of total daily energy intake) associated with a decrease in HDL cholesterol by 0.006 mmol/L (p < 0.001) when adjusted for saturated, monounsaturated and polyunsaturated fatty acid, age, gender, body mass index and STRIP study group. The inverse association between total carbohydrate intake and HDL cholesterol was evident in children with apoE3 (p < 0.001) or apoE4 (p < 0.001), but not in those with apoE2 (p = 0.78). An increase in total carbohydrate intake by 1 E% increased triglycerides by 0.02 mmol/L (p < 0.001) independently of apoE phenotype, while 1 E% increase in sucrose intake increased triglycerides by 0.01 mmol/L (p < 0.001).

CONCLUSION

Carbohydrate intake has a relatively small effect on serum lipids in children. Children with the apoE3 or E4 but not with E2 phenotype show reduction in HDL cholesterol with increasing carbohydrate intake indicating that genetic and environmental factors interact with children's lipoprotein metabolism.

APOE distribution in world populations with new data from India and the UK

BACKGROUND

The APOE gene and its protein product is associated with a number of plasma proteins like very-low density lipoprotein (VLDL), high density lipoprotein (HDL) chylomicrons, chylomicron remnants, and plays a crucial role in lipid metabolism. The APOE gene is polymorphic and common alleles (*E2, *E3 and *E4) have been associated with a number of common and complex diseases in different populations. Due to their crucial role in metabolism and clinical significance, it is imperative that allelic variation in different populations is analysed to evaluate the usage of APOE in an evolutionary and clinical context.

AIM

We report allelic variation at the APOE locus in three European and four Indian populations and evaluate global patterns of genetic variation at this locus. The large, intricate and unexpected heterogeneity of this locus in its global perspective may have insightful consequences, which we have explored in this paper.

SUBJECT AND METHODS

Apolipoprotein E genotypes were determined in four population groups (Punjabi Sikhs, Punjabi Hindus, Maria Gonds and Koch, total individuals = 497) of India and three regionally sub-divided British populations (Nottinghamshire, East Midlands and West Midlands, total individuals = 621). The extent and distribution of APOE allele frequencies were compared with 292 populations of the world using a variety of multivariate methods.

RESULTS

Three alleles, APOE*E2, APOE*E3 and APOE*E4, were observed with contrasting variation, although *E4 was absent in the tribal population of Koch. Higher heterozygosities (>43%) in British populations reflected their greater genetic diversity at this locus. The overall pattern of allelic diversity among these populations is comparable to many European and Indian populations. At a global level, higher frequencies of the *E2 allele were observed in Africa and Oceania (0.099 +/- 0.083 and 0.111 +/- 0.052, respectively). Similarly, *E4 allele averages were higher in Oceania (0.221 +/- 0.149) and Africa (0.209 +/- 0.090), while Indian and Asian populations showed the highest frequencies of *E3 allele. The coefficient of gene differentiation was found to be highest in South America (9.6%), although the highest genetic diversity was observed in Oceania (48.7%) and Africa (46.3%). APOE*E2 revealed a statistically significant decreasing cline towards the north in Asia (r = -0.407, d.f. = 70, p < 0.05), which is not compatible with the coronary heart disease statistics in this continent. APOE*E4 showed a significant increasing cline in North European populations. Spatial autocorrelation analysis shows that the variation at this locus is influenced by 'isolation by distance' with a strong positive correlation for lower distances up to 1313 km.

CONCLUSION

Overall APOE allelic variation in UK and Indian populations is comparable to previous studies but in tribal populations *E4 allele frequency was very low or absent. At a global level allelic variation shows that geography, isolation by distance, genetic drift and possibly pre-historical selection are responsible for shaping the spectrum of genetic variation at the APOE gene. Overall, APOE is a good anthropogenetic and clinical diagnostic marker.

Serum lipid and apolipoprotein profiles in newborns and six‐year‐old children: The Tallinn Young Family Study

Seventy children aged 6 years (34 boys, 36 girls) were studied for cardiovascular risk factors. Among the children 40 had also been investigated at birth. The aim of the study was to determine changes in serum lipoprotein parameters from birth up to preschool age and to assess the role of some relevant factors that might affect the process. An obvious association was found between serum apolipoprotein (apo) B levels, the apoB/apoA-I ratio and lipoprotein(a) (Lp(a)) levels at birth and at 6 years of age (r = 0.43; p<0.05, r = 0.73; p<0.0001 and r = 0.81; p<0.0001, respectively). Thirty percent of children who were in the top quartile by apoB or total cholesterol levels and 66.7% of those in this quartile by apoB/apoA-I ratio at birth remained in the top quartiles also in the follow-up study. The significantly higher apoB/apoA-I ratio in newborns and the apoB/apoA-I and apoB values in the 6-year-old children were observed in the carrier apoE4 isoform as compared to E3 homozygotes. A significant influence of apoE polymorphism on serum apoB/apoA-I ratio and apoB level in preschool children was confirmed by ANOVA one-way analysis of variance. In a multiple regression analysis from all the studied factors, the independent determinants of apoB level in preschool age were apoE phenotype, gestational age and Apgar score in the first minute of life. Thus, tracking of serum Lp(a), apoB, apoB/apoA-I ratio and total cholesterol levels from birth up to 6 years of age was demonstrated. The association between apoE polymorphism and serum lipoprotein parameters became more obvious after the first 6 years of life.

Improvement of myocardial blood flow by lipid‐lowering therapy with pravastatin is modulated by apolipoprotein E genotype

OBJECTIVE

Apolipoprotein E (apoE) polymorphism affects the risk of advanced coronary artery disease, but its role in early atherosclerosis remains unknown. We used positron emission tomography (PET) to study whether coronary reactivity or its response to pravastatin is related to the apoE genotype.

MATERIAL AND METHODS

Samples from 44 mildly hypercholesterolaemic men (aged 35 +/- 4 years) of an earlier trial were re-analysed according to apoE genotype. Subjects were randomized to receive either 40 mg/day pravastatin or placebo for 6 months. To assess coronary reactivity, myocardial blood flow was measured by PET at rest and during adenosine infusion. PET studies and lipid analyses were done at baseline and after 6 months of therapy.

RESULTS

There were no differences between apoE epsilon3/3 and epsilon4/3 genotypes in basal or adenosine-stimulated flow or in coronary flow reserve (CFR) at baseline. There was a significant apoE genotype-by-treatment group interaction regarding the change in adenosine-stimulated flow (ANCOVA; p = 0.018) and CFR (p = 0.020) at the end of the study. In the pravastatin group, the adenosine-stimulated flow increased by 32.5 % in subjects with epsilon3/3 (n = 9), but decreased non-significantly (-14.4 %) in subjects with epsilon4/3 (n = 9) (p = 0.0009). The corresponding changes in CFR were +17.8 % for epsilon3/3 and (-11.9 % for epsilon4/3 (p = 0.05). There were no significant changes from the baseline values in placebo recipients. After pravastatin treatment, both genotype groups showed a similar decrease in serum total and low-density lipoprotein cholesterol (p<0.0001 for both).

CONCLUSIONS

Coronary function improves by 6 months of pravastatin in subjects with the apoE epsilon3/3 genotype, but not in those with the epsilon4/3.

Effects of apolipoprotein E genotype on blood cholesterol in adolescent girls

BACKGROUND

Few investigations have examined whether associations between the apolipoprotein E genotype (apo E) and total cholesterol or LDL-C are modified or explained by other characteristics. The objective of this study was to explore effects of behavioral characteristics, physical growth, body composition, sexual maturation, and endocrine function on age trajectories of total cholesterol and LDL-C by apo E in adolescent girls.

METHODS

Participants were 247 Caucasian adolescent girls followed for 4 years. Apo E genotyping and plasma lipid concentrations were determined from fasting blood samples using standard enzymatic methods. Age; gender; fat-free mass (FFM); BMI; percent body fat (PBF); sexual maturation (pubic hair, Tanner Stages 1-5); estradiol concentration (EST); energy intake; and physical activity were collected or calculated with standard methods.

RESULTS

In models including the proposed explanatory variables, apo E genotype remained strongly associated with total cholesterol and LDL-C. Girls with the epsilon (epsilon)3/3 and epsilon3/4 genotypes (where epsilon is the protein isoform of the apo E gene), relative to those with epsilon2/3, had total cholesterol and LDL-C values 16-23 mg/dL higher throughout adolescence. Age-apo E interaction terms remained significant. FFM, BMI, PBF, pubic-hair stage, and EST showed a significant effect on total cholesterol and LDL-C. When the combination of pubic-hair stage, EST, and one of FFM, BMI, and PBF was included in total cholesterol or LDL-C models, only EST was significant.

CONCLUSIONS

Adolescent girls with epsilon3/3 and epsilon3/4 genotypes had higher total cholesterol and LDL-C and showed different patterns of change, compared to those with epsilon2/3 genotype. These apo E effects were independent of behavioral characteristics, physical growth, body composition, sexual maturation, and endocrine function. Girls with epsilon3/3 or epsilon3/4 genotypes may be at risk for elevated total cholesterol and LDL-C later in life.

Pharmacogenetics of apolipoprotein E gene during lipid-lowering therapy: lipid levels and prevention of coronary heart disease

A non-optimal plasma concentration of lipids is among the major modifiable risk factors of atherosclerosis. Therefore, the prevention of cardiovascular disease by means of lipid-lowering therapy with statins and other agents is of great importance for patient groups where a lifestyle change, for example, diet modification, does not lead to adequately reduced lipid levels. The response of low-density-lipoprotein cholesterol (LDL-C) levels to statin therapy is highly variable. This is partly attributed to hereditary variation in genes involved in pharmacokinetics, pharmacodynamics and lipid metabolism. The pharmacogenetics of lipid-lowering therapy have been investigated for more than 40 different genes. The gene for apolipoprotein E (APOE) has been the most frequently studied, particularly regarding the epsilon2/epsilon3/epsilon4 polymorphism. Those with the epsilon4 allele seem to have the poorest and those with the epsilon2 allele the strongest response to statins with regards to LDL-C levels. In addition, the epsilon2 carriers may reach the LDL-C treatment goals more frequently than epsilon4 carriers. Few studies have investigated the interaction of the APOE epsilon2/epsilon3/epsilon4 polymorphism and lipid-lowering therapy in relation to the course of coronary heart disease; the results are contradictory and so far inconclusive. This review summarizes the pharmacogenetic findings related to the influence of APOE gene variation on lipid responses and the prevention of coronary heart disease during lipid-lowering therapy.

Adult-type hypolactasia is not a predisposing factor for the early functional and structural changes of atherosclerosis: the Cardiovascular Risk in Young Finns Study

Individuals suffering from ATH (adult-type hypolactasia), defined by the LCT (gene encoding lactase-phlorizin hydrolase) C/C(-13910) genotype (rs4988235), use less milk and dairy products and may have higher plasma HDL (high-density lipoprotein) and lower triacylglycerol (triglyceride) concentrations than their counterparts without ATH. To investigate the effects of ATH status on the early markers of atherosclerosis, we examined its association with CIMT (carotid intima-media thickness), CAC (carotid artery compliance) and brachial artery FMD (flow-mediated dilation) in a young population-based cohort of otherwise healthy individuals. As part of the Cardiovascular Risk in Young Finns Study, we performed CIMT, CAC and FMD analyses, LCT C/T(-13910) genotyping and risk factor determination in 2109 young subjects 24-39 years of age (45% males) at the time of the examination. The consumption of both milk and dairy products was lowest and the consumption of alcohol highest in subjects with the C/C(-13910) genotype (P<0.001 for all) in comparison with subjects without ATH (TT+CT). In multivariate analysis, no significant association between ATH status and CIMT, CAC or brachial artery FMD was found after adjustment for the use of alcohol, dairy products and all other major risk factors of coronary artery disease. In otherwise similar statistical analysis, the results remained non-significant when females and males were analysed in their own groups. In conclusion, the finding does not support the involvement of ATH in the pathogenesis of early atherosclerosis.

Polymorphism in the IL6 promoter region is associated with the risk factors and markers of subclinical atherosclerosis in men: The Cardiovascular Risk in Young Finns Study

OBJECTIVE

Inflammatory factors modify the risk of coronary heart disease. Promoter region genetic polymorphism of inflammatory cytokine interleukin-6 (IL6 -174 G>C) is associated with the variation of IL-6 production. We investigated whether IL6 -174 G>C associates with the risk factors of atherosclerosis and carotid artery compliance (CAC) in young subjects.

METHODS AND RESULTS

As part of the Cardiovascular Risk in Young Finns Study, we performed carotid artery ultrasound examinations, IL6 -174 G>C genotyping and coronary heart disease risk factor determination for 2228 subjects aged 24-39 years. In men CAC was higher for IL6 -174 GG (2.10+/-0.65) than for GC (2.00+/-0.68) or CC (1.95+/-0.63, %/10mmHg, mean+/-S.D., p=0.0221). A similar association was observed for HDL cholesterol (GG 1.22+/-0.29, GC 1.15+/-0.27 and CC 1.14+/-0.28mmol/L, p=0.0015) and apolipoprotein A1 (apoA1) (GG 1.44+/-0.21, GC 1.40+/-0.20, CC 1.38+/-0.21mmol/L, p=0.0118). The opposite genotype effect was present in systolic (GG 127+/-13.1, GC 129+/-13.1, CC 130+/-14.3mmHg, p=0.0382) and diastolic blood pressure (GG 73.8+/-9.14, GC 75.1+/-8.68, CC 75.9+/-9.70mmHg, p=0.0374). The genetic effect size for these parameters was not significant in women.

CONCLUSIONS

IL6 -174 allele G homozygozity associates with beneficial profile of early predictors of atherosclerosis such as high CAC, HDL-C and apoA1 as well as low systolic and diastolic blood pressure in men.

Apolipoprotein E gene polymorphism and serum lipid levels in the Guangxi Hei Yi Zhuang and Han populations

Hei Yi Zhuang is an isolated subgroup of the Zhuang minority in China. Little is known about the distribution of apolipoprotein (apo) E genetic variations and its role in lipid metabolism in this population. The present study was undertaken to compare the effect of apoE gene polymorphism on serum lipid levels between the Guangxi Hei Yi Zhuang and Han populations. A total of 873 subjects of Hei Yi Zhuang and 867 participants of Han Chinese were surveyed by a stratified randomized cluster sampling. Genotyping of apoE was performed using polymerase chain reaction and restriction fragment length polymorphism. The frequencies of 2, 3, and 4 alleles were 15.23%, 79.84%, and 4.93% in Hei Yi Zhuang, and 9.23%, 81.43%, and 9.34% in Han (P < 0.001); respectively. The frequencies of 2/ 2, 2/ 3, 2/ 4, 3/ 3, 3/ 4, and 4/ 4 genotypes were 4.70%, 17.86%, 3.21%, 68.16%, 5.50%, and 0.57% in Hei Yi Zhuang, and 2.54%, 9.23%, 4.15%, 70.70%, 12.23%, and 1.15% in Han (P < 0.001); respectively. Total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and apoB levels were lower in Hei Yi Zhuang than in Han (P < 0.01-0.001), but high-density lipoprotein cholesterol (HDL-C) levels and the ratio of apoA-I to apoB were higher in Hei Yi Zhuang than in Han (P < 0.001 for each). There were significant differences in TC, HDL-C, LDL-C, and apoB levels among the six genotypes in both ethnic groups (P < 0.01-0.001). Hyperlipidemia was positively correlated with age, body mass index, hypertension, alcohol consumption, and apoE allele in both populations (P < 0.05-0.001). TC, LDL-C, and apoB levels were positively correlated, and HDL-C levels were negatively associated with apoE genotypes in both ethnic groups (P < 0.001 for all). The differences in the lipid profiles between Hei Yi Zhuang and Han Chinese might partly attribute to the differences in apoE genotypic and allelic frequencies.

Association of high sensitive C-reactive protein with apolipoprotein E polymorphism in children and young adults: the Cardiovascular Risk in Young Finns Study

BACKGROUND

A relation between apolipoprotein E (APOE) genotypes and high sensitive C-reactive protein (hsCRP) has been observed in some studies with elderly subjects and different patient groups. We studied whether serum hsCRP levels are linked with common APOE (epsilon 2, epsilon 3, epsilon 4) polymorphism already in children and young adults.

METHODS

The study cohort included 1221 subjects participating in the Cardiovascular Risk in Young Finns Study at age 3-18 years at baseline in 1980. These subjects were reexamined at the 21-year follow-up at age 24-39 years in 2001. APOE phenotypes were examined in 1986, serum hsCRP was measured from fresh samples in 2001 and baseline hsCRP (in 1980) was measured from frozen samples in 2005.

RESULTS

Serum hsCRP was significantly associated with APOE phenotypes in children and young adults using multivariate analysis adjusted for age, body mass index, smoking, total cholesterol and low-density lipoprotein cholesterol. Male epsilon 4 carriers had significantly lower hsCRP levels both in childhood (p=0.003) and in adulthood (p=0.013). hsCRP increased in both phenotype classes (epsilon 4+ and epsilon 4-) during the 21-year follow-up. Female epsilon 4 carriers had lower hsCRP levels in childhood (p=0.032) but not in adulthood (p=0.995). An interaction effect between time and APOE phenotype (p=0.045) in relation to hsCRP was observed in females during the 21-year follow-up.

CONCLUSIONS

Common APOE polymorphism affects the level of circulating hsCRP already in children and young adults. Male APOE epsilon 4 carriers have consistently lower hsCRP levels. In females, APOE epsilon 4 carriers had lower hsCRP levels in childhood but not in adulthood.

Apolipoprotein polymorphisms and familial hypercholesterolemia

The majority of apolipoproteins known to play a major role in lipid metabolism were identified over 20 years ago, and nine of them (APOA1, -A2, -A4, -B48, -B100, -C1, -C2, -C3 and -E) have long been known to be most relevant to the regulation of lipoproteins. Polymorphisms of genes encoding apolipoproteins influence plasma levels of high-density lipoproteins (HDL), very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL) chylomicrons or triglycerides. Familial hypercholesterolemia (FH), an autosomal dominant disorder, is caused by mutations mainly located in the low-density lipoprotein receptor (LDLR) gene, or more rarely within the apolipoprotein B-100 gene or the gene encoding a secreted proteinase PSCK9. FH is characterized by elevated concentrations of LDL, deposition of LDL-derived cholesterol in tendons, skin xanthomas, and premature coronary artery disease. The frequency of heterozygotes is approximately one in 500 persons, placing FH among the most common inborn errors of metabolism. The risk of cardiovascular disease in these patients is influenced not only by the type of the mutations they carry, but also by the haplotype of lipid modifier genes, as is the case of apolipoproteins. In this review, we present current information that demonstrates the impact of apolipoprotein polymorphisms on the FH phenotype.

Relation of apolipoprotein E polymorphism to markers of early atherosclerotic changes in young adults--the Cardiovascular Risk in Young Finns Study

BACKGROUND

Carotid artery intima-media thickness (IMT), which is measured by ultrasound, is used in the assessment of early atherosclerotic changes, and has been associated with apolipoprotein E (APOE) polymorphism in many studies comprising elderly subjects. However, results are still inconclusive and data relating to young adults are missing. Whether common APOE polymorphism is related to carotid IMT was studied in a population of young adults. Also brachial flow-mediated dilatation (FMD) and carotid artery compliance (CAC) were determined to clarify their relation to this genetic factor.

METHODS AND RESULTS

A total of 1,188 young adults (aged 24-39 years) participating in the Cardiovascular Risk in Young Finns Study with complete data of common APOE polymorphism underwent a carotid and brachial ultrasound. Patients' lipid levels and blood pressure were also examined. There was no significant association between the APOE phenotypes and carotid IMT, brachial FMD or CAC either in young men or in young women. The results were similar for systolic and diastolic blood pressure. In the same population, the well-known association between APOE phenotypes and lipids was seen.

CONCLUSIONS

Common APOE polymorphism does not seem to be an independent genetic determinant of carotid IMT, brachial FMD or CAC.

Influence of apolipoprotein E polymorphism on serum lipid and lipoprotein changes: a 21-year follow-up study from childhood to adulthood. The Cardiovascular Risk in Young Finns Study

BACKGROUND

We examined the influence of apolipoprotein E (apoE) polymorphism on longitudinal changes in serum lipids by following the subjects participating in The Cardiovascular Risk in Young Finns Study over a 21-year period.

METHODS

Serum lipids were determined in randomly selected Finnish children and adolescents in 1980 and the subjects were re-examined in 1983, 1986 and after 21 years in 2001. ApoE polymorphism was determined in 1736 participants, and serum lipid values and apoE phenotypes were available for 1233 subjects.

RESULTS

ApoE phenotype-related differences in serum total and low-density lipoprotein (LDL)-cholesterol were maintained throughout the 21-year follow-up from childhood to adulthood, i.e., the apoE epsilon2 allele was consistently associated with lower and the epsilon4 allele with higher total and LDL-cholesterol (p<0.001 for all). In adulthood, there was also a significant apoE phenotype-related difference in high-density lipoprotein (HDL)-cholesterol (p=0.007), and the epsilon2 allele was associated with higher and the epsilon4 allele with lower apoA-I and HDL-cholesterol. In addition, apoB increased in the phenotype order E3/2<E3/3<E4 (E4/3+E4/4) (p<0.001). The LDL-lowering effect of the epsilon2 allele was greater in adulthood than in childhood, i.e., there was a significant apoE phenotypextime interaction (p=0.039) with longitudinal change in LDL-cholesterol.

CONCLUSIONS

ApoE polymorphism is associated with lipid levels at different ages and affects the longitudinal change in LDL-cholesterol from childhood to adulthood.

Role of apolipoprotein E genotype in coronary artery disease

Recent gene-targeting technology has provided good animal models that provide insight into the pathology of complex diseases such as atherosclerosis. The apolipoprotein E gene polymorphism is one of the most extensively studied in cardiovascular medicine. The scope of the present review is to briefly outline the biochemical characteristics and the genetic variation of apolipoprotein E. Apolipoprotein E is best known for its role in modulating lipoprotein metabolism as a ligand for cellular receptors. Other functions unrelated to lipid transport are becoming known, including reverse cholesterol transport, immunoregulation and modulation of cell growth. This review will examine recent work that addresses how apolipoprotein E participates in atherosclerosis. Genotypic variation of apolipoprotein E has been associated with certain phenotypes regarding vascular disease, such as the presence of atherosclerosis and coronary heart disease outcomes. This article will also review evidence regarding the association between apolipoprotein E gene polymorphisms and coronary artery disease based upon experimental and clinical studies.

Apolipoprotein E polymorphism in Southern Iran: E4 allele in the lowest reported amounts

BACKGROUND

Apolipoprotein E (apoE) with three major alleles E2, E3 and E4 is one of the critical genes in lipid metabolism. Common apoE alleles are in association with an increase in risk for central nervous and cardiovascular diseases such as Alzheimer's disease, dementia, multiple sclerosis, atherosclerosis, coronary heart disease, hyperlipoproteinemia and stroke. ApoE3 is known as the most frequent allele in all populations, while association of apoE gene polymorphism with reported diseases have mostly been related to other two major alleles especially apoE4.

OBJECTIVE

To determine of apoE alleles frequencies in Southern Iran and comparison of those frequencies with other populations.

METHODS

DNA was extracted from the whole blood of 198 healthy unrelated candidates from population of Fars Province, Southern Iran, for apoE genotyping who were checked up by a physician. The frequencies of apoE alleles were compared with other populations by chi(2) test.

RESULTS

The frequencies of E2, E3 and E4 were 0.063, 0.886 and 0.051 respectively. These values were similar to those reported from populations of Kuwait, Oman, Lebanon, India, Turkey, Greece, Spain, Sardinia Islands of Italy and two Iranian populations but were different from South of Italy and Caucasians in other Europe regions, American, American-Indian, African, East Asian and Saudi populations (P < 0.05).

CONCLUSION

The frequency of E4 allele as a genetic risk factor for some multifactorial diseases in the population of Southern Iran is in the lowest reported amounts in the world. Iranian population has Caucasoid origin but differs from some Caucasian populations in Europe and America. The results of present study are in agreement with the historical evidences which show admixture of Iranian population with other populations and some studies based on genetic polymorphisms in the population of Southern Iran.

Subclinical vitamin K deficiency in hemodialysis patients

BACKGROUND

Subclinical vitamin K deficiency increasingly is associated with extraosseous calcification in healthy adults. Nondietary determinants of vitamin K status include apolipoprotein E (apoE) genotype, which may influence vitamin K transport to peripheral tissues.

METHODS

Serum phylloquinone concentrations and percentage of uncarboxyated osteocalcin (%ucOC) were measured by means of high-performance liquid chromatography and radioimmunoassay in 142 hemodialysis patients, respectively. ApoE phenotype was determined by means of isoelectric focusing of delipidated serum samples and Western blot analysis. Clinical and laboratory data were obtained by using chart review.

RESULTS

Mean age was 62.6 +/- 14.8 (SD) years. Mean phylloquinone level was 0.99 +/- 1.12 nmol/L; 29% of patients had levels less than 0.4 nmol/L. There was no association between phylloquinone level and %ucOC. There were positive correlations between phylloquinone and total cholesterol (P = 0.017), triglyceride (P = 0.022), and ionized calcium levels (P = 0.019). There was a negative correlation between phylloquinone level and dialysis adequacy (P = 0.002). Mean %ucOC was 51.1% +/- 25.8%, and 93% of subjects had values greater than 20%. There were positive correlations between %ucOC and dialysis vintage (P < 0.001), phosphate level (P < 0.001), parathyroid hormone level (P < 0.001), albumin level (P = 0.035), and ionized calcium level (P = 0.046). Seventeen percent of patients were apoE4. Mean %ucOC was significantly greater in apoE4 carriers compared with all other apoE phenotypes (60.1% +/- 28.4% versus 47.8% +/- 24.4%; P = 0.035). In multiple regression analysis with phylloquinone level forced in, independent predictors of %ucOC were phosphate level, dialysis vintage, parathyroid hormone level, and apoE4.

CONCLUSION

These data indicate suboptimal vitamin K status in hemodialysis patients, shown by low phylloquinone concentrations and high %ucOC in 29% and 93% of subjects, respectively. The apoE4 allele influences osteocalcin gamma-carboxylation in hemodialysis patients.

Low-density lipoprotein (LDL) particle size in healthy prepubertal children: the STRIP study

BACKGROUND

Small, dense low-density lipoprotein (LDL) particles (diameter < 255 Angstrom) are highly atherogenic, and in adults they are associated with an elevated risk of coronary heart disease (CHD).

AIM

To examine possible contributors to LDL particle size distribution in healthy prepubertal children.

METHODS

We determined LDL particle size in 176 7-y-old children by non-denaturing polyacrylamide gel electrophoresis. Children were divided into two groups in two ways: by using the median of their average LDL particle diameter (261.2 Angstrom) or by using the LDL peak particle diameter (255 Angstrom) as the cut-off point.

RESULTS

Children with smaller LDL particles did not significantly differ from children with larger LDL particles with respect to anthropometric variables, serum triglyceride concentration (in all children < 1.7 mmol/L), apoE phenotype, amount and quality of dietary fat, or child's family history of CHD. Furthermore, LDL particle size did not correlate with any of the anthropometric, lipid or nutrient variables. Children with average LDL particle size below the median had higher serum insulin and lower high-density lipoprotein (HDL) cholesterol and apoA-1 concentrations than those with LDL particle size above the median.

CONCLUSION

Our data suggest that many factors related to the development of small, dense LDL particles might have their major impact after the onset of puberty.

Relations of APOE promoter polymorphisms to LDL cholesterol and markers of subclinical atherosclerosis in young adults

The common apolipoprotein E (apoE) gene (APOE) epsilon2/epsilon3/epsilon4 polymorphism explains part of serum lipid variation, and polymorphisms in the APOE promoter region have been proposed to participate in the regulation of serum lipid levels within the most common APOE epsilon3/epsilon3 genotype group. We determined APOE -219G/T and +113G/C promoter genotypes and estimated APOE haplotypes in 525 participants of the Cardiovascular Risk in Young Finns Study. We studied the associations of the APOE promoter polymorphisms and their haplotypes with cross-sectional and longitudinal serum lipid and apolipoprotein concentrations as well as with flow-mediated dilatation (FMD), carotid artery compliance (CAC), and intima-media thickness (IMT) within the APOE epsilon3/epsilon3 carriers. We found no significant association between the APOE promoter genotypes and serum lipids [low density lipoprotein-cholesterol (LDL-C), HDL-C, and triglycerides], apolipoproteins (apoA-I and apoB), or brachial artery FMD, CAC, or carotid IMT in either men or women. In longitudinal analyses in males, the carriers of heterozygous genotypes (-219G/T or +113G/C) and, furthermore, carriers of the -219T/+113C/epsilon3 haplotype had significantly higher LDL-C and total cholesterol concentrations throughout the 21 year follow-up period compared with homozygous G allele carriers or noncarriers of the -219T/+113C/epsilon3 haplotype. Such associations were not found in females. In summary, the APOE promoter polymorphisms -219G/T and +113G/C as well as their haplotype are associated with longitudinal changes in LDL-C and total cholesterol concentrations in young Finnish males but do not seem to be major determinants for FMD, CAC, or carotid IMT in males or females.

Apolipoprotein E genotype is related to plasma levels of C-reactive protein and lipids and to longevity in nonagenarians

OBJECTIVE

Apolipoprotein E (APOE) genotype is a regulator of hepatic lipoprotein metabolisms and has been linked with longevity. The relationship between APOE genotype and plasma C-reactive protein (CRP), which is produced by the liver during inflammation, has not been studied in nonagenarians. The aim of the present study was to establish whether APOE genotype is related to plasma concentrations of CRP and lipids, or longevity among nonagenarians.

DESIGN AND PATIENTS

This cross-sectional study consisted of 291 Finnish nonagenarians and three previously described and genotyped control populations from the same area (i.e. newborns, 40-year-olds, and 70-year-olds).

RESULTS

In all nonagenarians and especially in women (P= 0.038), CRP level decreased linearly in the genotype order of epsilon2/2, epsilon2/3, epsilon3/3, epsilon2/4, epsilon3/4 and epsilon4/4. Total (P= 0.009) and low-density lipoprotein (LDL) cholesterol (P = 0.076) levels, in turn, were increased in the epsilon4 allele carriers. In newborns, the epsilon4 frequency was 0.192, in 40-year-olds 0.181, in 70-year-olds 0.179 and in nonagenarians 0.095 (P < 0.0001). The decrease in the epsilon4 allele frequency in the elderly was more clearly seen in women than in men.

CONCLUSIONS

APOEepsilon4 allele seems to be associated with decreased inflammatory response as measured by CRP among nonagenarians. This finding may partly explain why some epsilon4 allele carriers can reach very old age despite increased risk of hypercholesterolaemia.

Association of apolipoprotein E genotype with early onset of coronary heart disease in Greek men

Apolipoprotein (apo) E polymorphism has been associated with coronary heart disease (CHD) although its relation to the age of CHD onset is still not defined. The age of onset of established CHD was obtained from 502 Greek men and compared to 103 healthy men. The age grouping was based on the age of CHD onset (earlier < or =44 years, n = 73, intermediate 45-64 years, n = 321, and later > or =65 years, n = 108). Apo E genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the lipid profile was assessed. No differences in genotype and allele frequencies were found within the CHD groups. The apo epsilon3/4 genotype and the apo epsilon4 allele were less frequent in the earlier-onset group than in healthy men (11.0 % vs 22.3%, Pearson Chi-Square p = 0.028 and 6.8% vs 13.6%, Pearson Chi-Square p = 0.023, respectively). The lipid profile was similar in all genotypes of all groups except for high-density lipoprotein cholesterol levels, which were higher in epsilon2 carriers compared to non-epsilon2 carriers (in mg/dL [+/-SD]; 44 [9] vs 39 [10], in mmol/L [+/-SD]; 1.1 [0.2] vs 1.0 [0.3] p = 0.005). There is an association between apo E genotype and early onset of CHD in Greek men. In the earlier CHD onset group, the apo epsilon3/4 genotype was less frequent compared to healthy men. This supports that the apo epsilon3/4 genotype is associated with decreased risk of premature CHD. Because the results of similar studies are not consistent, it may be that the relationship between apo E genotype and CHD is related to ethnicity rather than a universal phenomenon.

Cholesterol Absorption and Synthesis in Pediatric Kidney, Liver, and Heart Transplant Recipients

BACKGROUND

Hypercholesterolemia after organ transplantation is common. Previously, we observed higher serum total cholesterol (TC) concentrations in our pediatric kidney than liver or heart transplant recipients. To find an explanation to the observed difference, our kidney recipients' cholesterol synthesis and absorption efficiency was compared to those of liver and heart recipients.

METHODS

Serum noncholesterol sterol ratios (10 x mmol to the mol of TC, surrogate estimates of hepatic cholesterol synthesis and intestinal absorption) were studied in 50 pediatric kidney, 25 liver and 12 heart transplant recipients without diabetes or cholestasis, and in 29 controls.

RESULTS

The kidney recipients had lower Delta-cholesterol (P=0.031), similar lathosterol and higher desmosterol ratios (markers of cholesterol synthesis) (P=0.020), and similar campesterol and sitosterol ratios (markers of cholesterol absorption) when compared to the controls. The liver recipients had lower campesterol ratios than the kidney recipients and controls (P=0.002). Glomerular filtration rates were not associated with the ratios of noncholesterol sterols. Multivariate analysis showed markers of cholesterol synthesis to be lower and absorption to be higher in the kidney than the liver or the heart transplant recipients. Weight-adjusted dosages of immunosuppressive agents were associated with some ratios of noncholesterol sterols and cholestanol though these varied between the transplant recipient groups.

CONCLUSIONS

Serum TC concentration in kidney recipients was not significantly associated with absorption efficiency or synthesis of cholesterol, though kidney transplantation was associated with low synthesis and high absorption efficiency of cholesterol. Immunosuppressive therapy with cyclosporine and methylprednisolone may modulate absorption efficiency and synthesis of cholesterol.

Contributors to white matter damage in the frontal lobe in Alzheimer's disease

Abnormalities of cerebral white matter are present in a majority of patients with Alzheimer's disease (AD) and probably contribute to motor dysfunction and cognitive impairment. The white matter abnormalities are usually attributed to degenerative vascular disease and cerebral amyloid angiopathy (CAA) but the evidence is scanty or inconclusive. In the present study we examined sections of frontal lobe from 125 autopsy-confirmed cases of AD and assessed the relationship of degenerative large and small vessel disease, CAA, parenchymal Abeta load and APOE genotype, to several objective measures of white matter damage: extent of immunolabelling for glial fibrillary acidic protein (GFAP), axonal accumulation of amyloid precursor protein (APP), axon density in superficial and deep white matter, and intensity of staining for myelin. We found no association between atherosclerosis, arteriolosclerosis, CAA or APOE genotype and white matter damage. However, labelling of white matter for GFAP correlated strongly with the parenchymal Abeta load (P = 0.0003) and with APP accumulation (P = 0.008). Our findings suggest that severity of frontal white matter damage in AD is closely related to parenchymal Abeta load and that in most cases the contribution of degenerative vascular disease, CAA and APOE is relatively minor.

Blood leukocyte count is a risk factor for intima-media thickening and subclinical carotid atherosclerosis in middle-aged men

Leukocytosis is known to predict future cardiovascular events even in subjects without coronary heart disease (CHD), but its association with early atherosclerotic changes has remained less certain. The aim of the present study was to investigate how the blood leukocyte count compares with several other risk factors for CHD in determining carotid artery intima-media thickness (IMT) and subclinical carotid atherosclerosis in a population sample. Both carotid arteries were investigated with high-resolution B-mode ultrasound in a community-based sample of 219 randomly selected men aged 50-59 years to calculate the mean maximum IMT (MMax IMT) of 12 standard sites. Risk factor assessment included several traditional biochemical risk factors, blood pressure, maximal oxygen consumption and work load on ergometry, life-style habits and hematologic parameters. As genetic determinants, apolipoprotein E and A-IV polymorphisms were studied. According to multivariate regression analysis, age (P<0.0001), blood leukocyte count (P<0.0001) and systolic blood pressure (P<0.042) were the only significant predictors of MMax IMT. MMax IMT increased linearly from the lowest tertile of blood leukocyte count (1.14+/-0.20mm) to the second (1.18+/-0.25 mm) and to the highest tertile (1.25+/-0.27 mm, P=0.019). This difference remained significant after adjustment with age, systolic blood pressure and smoking (P=0.032). Leukocytes seem to have an independent role in the early arterial damage and they may reflect subclinical disease. This implies that leukocyte count is undervalued in the diagnostics and prognostics of carotid atherosclerosis.

Incidence of dementia in very elderly individuals: a clinical, neuropathological and molecular genetic study

AIMS

To evaluate the effect of medical record use on figures for the incidence of dementia and the effect of apolipoprotein E (APOE) polymorphism on this incidence and neuropathologically defined Alzheimer's disease (AD) in very elderly individuals.

METHODS

Cognitive functions were examined in a cohort of 328 (92% of the very elderly people of a town participated in this study) nondemented Finnish elderly individuals 85 years of age or more in 1991. The examination was repeated in survivors in 1994, 1996, 1999 and 2001. Medical notes and social work records were evaluated. All these individuals were genotyped for APOE. Neuropathological analysis of AD-type pathology was performed on 159 of 303 subjects who died during the follow-up.

RESULTS

Age group, gender or APOE did not significantly affect the incidence of dementia, which was over 20% higher (85 vs. 69 per 1,000 person-years) if the cognitive status at death was ascertained by medical and social work records than without this evaluation. The APOE upsilon4 allele was highly significantly (p=0.002) and age almost significantly (p=0.06) associated with neuropathological AD in nondemented individuals.

CONCLUSIONS

Medical records should be analyzed in studies on the incidence of dementia in very elderly individuals. APOE polymorphism does not affect the incidence of dementia in this age group. However, clinical dementia diagnosis in very elderly individuals does not necessarily correlate well with the presence of neuropathological AD which, even in this age group, is significantly associated with the APOE upsilon4 allele.

Influence of apolipoprotein E genotype on fat-soluble plasma antioxidants in Spanish children

BACKGROUND

Apolipoprotein (apo) E is a major determinant of plasma lipid concentrations, which in turn influence the plasma concentrations of various fat-soluble vitamins.

OBJECTIVE

We aimed to analyze the effect of APOE genotype on fat-soluble antioxidant concentrations in children.

DESIGN

A total of 926 healthy boys and girls aged 6-8 y were selected from 4 cities in Spain. APOE genotyping was carried out, and plasma concentrations of lipids, apolipoproteins, and lipid-soluble antioxidants were measured.

RESULTS

Plasma lipid concentrations were strongly influenced by APOE genotype. The mean plasma concentration of alpha-tocopherol was 21.3 micromol/L, which is one of the highest values ever reported for a population of children. Although plasma concentrations of alpha-tocopherol, gamma-tocopherol, lycopene, and alpha-carotene varied significantly between subjects with different APOE genotypes, most of these differences disappeared after adjustment for lipoprotein-related covariates. Nevertheless, tocopherol concentrations remained elevated in individuals with the E2/2 genotype. Multivariate regression analysis showed interactions of APOE genotype with triacylglycerol and apo B in determining alpha-tocopherol concentrations. When subjects were stratified according to major apo E groups, apo B appeared to be the most important predictor of alpha-tocopherol concentrations in all groups, whereas triacylglycerol was identified only in carriers of the E2 allele.

CONCLUSIONS

The association between APOE genotype and lipophilic antioxidant concentrations is dependent mainly on the effect of the polymorphism on lipoprotein concentrations. However, triacylglycerol plays a role in determining the variability of alpha-tocopherol concentrations in E2 carriers only. This suggests that the alpha-tocopherol content in each lipoprotein class varies according to APOE genotype.