Isolation, characterization, and mapping to chromosome 19 of the human apolipoprotein E gene

Human apolipoprotein E glycosylation and sialylation: from structure to function

Human apolipoprotein E (ApoE) was first identified as a polymorphic gene in the 1970s; however, the genetic association of ApoE genotypes with late-onset sporadic Alzheimer's disease (sAD) was only discovered 20 years later. Since then, intensive research has been undertaken to understand the molecular effects of ApoE in the development of sAD. Despite three decades' worth of effort and over 10,000 papers published, the greatest mystery in the ApoE field remains: human ApoE isoforms differ by only one or two amino acid residues; what is responsible for their significantly distinct roles in the etiology of sAD, with ApoE4 conferring the greatest genetic risk for sAD whereas ApoE2 providing exceptional neuroprotection against sAD. Emerging research starts to point to a novel and compelling hypothesis that the sialoglycans posttranslationally appended to human ApoE may serve as a critical structural modifier that alters the biology of ApoE, leading to the opposing impacts of ApoE isoforms on sAD and likely in the peripheral systems as well. ApoE has been shown to be posttranslationally glycosylated in a species-, tissue-, and cell-specific manner. Human ApoE, particularly in brain tissue and cerebrospinal fluid (CSF), is highly glycosylated, and the glycan chains are exclusively attached via an O-linkage to serine or threonine residues. Moreover, studies have indicated that human ApoE glycans undergo sialic acid modification or sialylation, a structural alteration found to be more prominent in ApoE derived from the brain and CSF than plasma. However, whether the sialylation modification of human ApoE has a biological role is largely unexplored. Our group recently first reported that the three major isoforms of human ApoE in the brain undergo varying degrees of sialylation, with ApoE2 exhibiting the most abundant sialic acid modification, whereas ApoE4 is the least sialylated. Our findings further indicate that the sialic acid moiety on human ApoE glycans may serve as a critical modulator of the interaction of ApoE with amyloid β (Aβ) and downstream Aβ pathogenesis, a prominent pathologic feature in AD. In this review, we seek to provide a comprehensive summary of this exciting and rapidly evolving area of ApoE research, including the current state of knowledge and opportunities for future exploration.

Relation between Apolipoprotein E in Alzheimer's Disease and SARS-CoV-2 and their Treatment Strategy: A Review

COVID-19, which primarily affects the pulmonary system, turned out to be a global pandemic, whereas the effects on other systems are still unknown. SARS-CoV-2, binds to angiotensinconverting enzyme 2 (ACE2) receptors in the lungs, causing pneumonia-like symptoms. The same ACE receptors are also present in organs other than the lungs. Therefore, there is a need to study the impact of coronavirus on other human body organs. Recently, UK Biobank reports on the genetic risk factor of the virus attack. A double mutation in the apolipoprotein E (APOE4) allele has shown a significant role in COVID-19. The same APOE4 mutation has already been proven to hold a key role in developing early-onset Alzheimer's disease (EOAD). Despite this data, Alzheimer's disease is believed to be a comorbidity of COVID-19. Previous virus attacks on the same viral family, Coronaviridae, produced neurological effects like neurodegeneration, neuronal inflammation, and other central nervous system-related dysfunctions. Since the long-term implications of COVID-19 are unknown, more research into the impact of the virus on the central nervous system is needed. Both COVID-19 and AD share a common genetic factor, so that AD patients may have a greater risk of SARS-CoV-2. Here, in this review, we have briefly discussed the role of APOE4 in the pathogenesis of AD and SARS-CoV-2, along with their treatment strategy, current scenario, and possible future directions.

An in-silico insight into the predictive interaction of Apolipoprotein-E with Epstein-Barr virus proteins and their probable role in mediating Alzheimer's disease

Recent reports suggest that persistent Epstein-Barr virus (EBV) infection and its recurrent reactivation could instigate the formation of proteinaceous plaques in the brain: a hallmark of Alzheimer's disease (AD). Interestingly, a major genetic risk factor of AD, the apolipoprotein E (ApoE), could also influence the outcome of EBV infection in an individual. The ApoE is believed to influence the proteinaceous plaque clearance from the brain, and its defective functioning could result in the aggregate deposition. The persistent presence of EBV infection in a genetically predisposed individual could create a perfect recipe for severe neurodegenerative consequences. Therefore, in the present study, we investigated the possible interactions between ApoE and various EBV proteins using computational tools. Our results showed possibly stable de-novo interactions between the C-terminal domain of ApoE3 and EBV proteins: EBV nuclear antigen-1 (EBNA1) and BamHI Z fragment leftward open reading frame-1 (BZLF1). The EBNA1 protein of EBV plays a crucial role in establishing latency and replication of the virus. Whereas BZLF1 is involved in the lytic replication cycle. The proposed interaction of EBV proteins at the ligand-binding site of ApoE3 on CTD could interfere with- its capability to sequester amyloid fragments and, hence their clearance from the brain giving rise to AD pathology. This study provides a new outlook on EBV's underexplored role in AD development and paves the way for novel avenues of investigation which could further our understanding of AD pathogenesis.Communicated by Ramaswamy H. Sarma[Figure: see text].

APOE in the bullseye of neurodegenerative diseases: impact of the APOE genotype in Alzheimer's disease pathology and brain diseases

ApoE is the major lipid and cholesterol carrier in the CNS. There are three major human polymorphisms, apoE2, apoE3, and apoE4, and the genetic expression of APOE4 is one of the most influential risk factors for the development of late-onset Alzheimer's disease (AD). Neuroinflammation has become the third hallmark of AD, together with Amyloid-β plaques and neurofibrillary tangles of hyperphosphorylated aggregated tau protein. This review aims to broadly and extensively describe the differential aspects concerning apoE. Starting from the evolution of apoE to how APOE's single-nucleotide polymorphisms affect its structure, function, and involvement during health and disease. This review reflects on how APOE's polymorphisms impact critical aspects of AD pathology, such as the neuroinflammatory response, particularly the effect of APOE on astrocytic and microglial function and microglial dynamics, synaptic function, amyloid-β load, tau pathology, autophagy, and cell-cell communication. We discuss influential factors affecting AD pathology combined with the APOE genotype, such as sex, age, diet, physical exercise, current therapies and clinical trials in the AD field. The impact of the APOE genotype in other neurodegenerative diseases characterized by overt inflammation, e.g., alpha- synucleinopathies and Parkinson's disease, traumatic brain injury, stroke, amyotrophic lateral sclerosis, and multiple sclerosis, is also addressed. Therefore, this review gathers the most relevant findings related to the APOE genotype up to date and its implications on AD and CNS pathologies to provide a deeper understanding of the knowledge in the APOE field.

Lipoproteins in the Central Nervous System: From Biology to Pathobiology

The brain, as one of the most lipid-rich organs, heavily relies on lipid transport and distribution to maintain homeostasis and neuronal function. Lipid transport mediated by lipoprotein particles, which are complex structures composed of apolipoproteins and lipids, has been thoroughly characterized in the periphery. Although lipoproteins in the central nervous system (CNS) were reported over half a century ago, the identification of APOE4 as the strongest genetic risk factor for Alzheimer's disease has accelerated investigation of the biology and pathobiology of lipoproteins in the CNS. This review provides an overview of the different components of lipoprotein particles, in particular apolipoproteins, and their involvements in both physiological functions and pathological mechanisms in the CNS.

Hyperphosphorylated Human Tau Accumulates at the Synapse, Localizing on Synaptic Mitochondrial Outer Membranes and Disrupting Respiration in a Mouse Model of Tauopathy

Neurogenerative disorders, such as Alzheimer’s disease (AD), represent a growing public health challenge in aging societies. Tauopathies, a subset of neurodegenerative disorders that includes AD, are characterized by accumulation of fibrillar and hyperphosphorylated forms of microtubule-associated protein tau with coincident mitochondrial abnormalities and neuronal dysfunction. Although, in vitro, tau impairs axonal transport altering mitochondrial distribution, clear in vivo mechanisms associating tau and mitochondrial dysfunction remain obscure. Herein, we investigated the effects of human tau on brain mitochondria in vivo using transgenic htau mice at ages preceding and coinciding with onset of tauopathy. Subcellular proteomics combined with bioenergetic assessment revealed pathologic forms of tau preferentially associate with synaptic over non-synaptic mitochondria coinciding with changes in bioenergetics, reminiscent of an aged synaptic mitochondrial phenotype in wild-type mice. While mitochondrial content was unaltered, mitochondrial maximal respiration was impaired in synaptosomes from htau mice. Further, mitochondria-associated tau was determined to be outer membrane-associated using the trypsin protection assay and carbonate extraction. These findings reveal non-mutant human tau accumulation at the synapse has deleterious effects on mitochondria, which likely contributes to synaptic dysfunction observed in the context of tauopathy.

Genetic Regulatory Networks of Apolipoproteins and Associated Medical Risks

Apolipoproteins (APO proteins) are the lipoprotein family proteins that play key roles in transporting lipoproteins all over the body. There are nearly more than twenty members reported in the APO protein family, among which the A, B, C, E, and L play major roles in contributing genetic risks to several disorders. Among these genetic risks, the single nucleotide polymorphisms (SNPs), involving the variation of single nucleotide base pairs, and their contributing polymorphisms play crucial roles in the apolipoprotein family and its concordant disease heterogeneity that have predominantly recurred through the years. In this review, we have contributed a handful of information on such genetic polymorphisms that include APOE, ApoA1/B ratio, and A1/C3/A4/A5 gene cluster-based population genetic studies carried throughout the world, to elaborately discuss the effects of various genetic polymorphisms in imparting various medical conditions, such as obesity, cardiovascular, stroke, Alzheimer's disease, diabetes, vascular complications, and other associated risks.

The Role of ApoE Expression and Variability of Its Glycosylation in Human Reproductive Health in the Light of Current Information

Apolipoprotein E (ApoE), a 34-kDa glycoprotein, as part of the high-density lipoprotein (HDL), has antioxidant, anti-inflammatory and antiatherogenic properties. The variability of ApoE expression in the course of some female fertility disorders (endometriosis, POCS), and other gynecological pathologies such as breast cancer, choriocarcinoma, endometrial adenocarcinoma/hyperplasia and ovarian cancer confirm the multidirectional biological function of ApoE, but the mechanisms of its action are not fully understood. It is also worth taking a closer look at the associations between ApoE expression, the type of its genotype and male fertility disorders. Another important issue is the variability of ApoE glycosylation. It is documented that the profile and degree of ApoE glycosylation varies depending on where it occurs, the type of body fluid and the place of its synthesis in the human body. Alterations in ApoE glycosylation have been observed in the course of diseases such as preeclampsia or breast cancer, but little is known about the characteristics of ApoE glycans analyzed in human seminal and blood serum/plasma in the context of male reproductive health. A deeper analysis of ApoE glycosylation in the context of female and male fertility will both enable us to broaden our knowledge of the biochemical and cellular mechanisms in which glycans participate, having a direct or indirect relationship with the fertilization process, and also give us a chance of contributing to the enrichment of the diagnostic panel in infertile women and men, which is particularly important in procedures involved in assisted reproductive techniques. Moreover, understanding the mechanisms of glycoprotein glycosylation related to the course of various diseases and conditions, including infertility, and the interactions between glycans and their specific ligands may provide us with an opportunity to interfere with their course and thus develop new therapeutic strategies. This brief overview details some of the recent advances, mainly from the last decade, in understanding the associations between ApoE expression and some female and male fertility problems, as well as selected female gynecological diseases and male reproductive tract disorders. We were also interested in how ApoE glycosylation changes influence biological processes in the human body, with special attention to human fertility.

Plasma Apolipoprotein E3 and Glucose Levels Are Associated in APOE ɛ3/ɛ4 Carriers

BACKGROUND

Altered cerebral glucose metabolism, especially prominent in APOE ɛ4 carriers, occurs years prior to symptoms in Alzheimer's disease (AD). We recently found an association between a higher ratio of plasma apolipoprotein E4 (apoE4) over apoE3, and cerebral glucose hypometabolism in cognitively healthy APOE ɛ3/ɛ4 subjects. Plasma apoE does not cross the blood-brain barrier, hence we speculate that apoE is linked to peripheral glucose metabolism which is known to affect glucose metabolism in the brain.

OBJECTIVE

Explore potential associations between levels of plasma insulin and glucose with previously acquired plasma apoE, cerebral metabolic rate of glucose (CMRgl), gray matter volume, and neuropsychological test scores.

METHODS

Plasma insulin and glucose levels were determined by ELISA and a glucose oxidase assay whereas apoE levels were earlier quantified by mass-spectrometry in 128 cognitively healthy APOE ɛ3/ɛ4 subjects. Twenty-five study subjects had previously undergone FDG-PET and structural MRI.

RESULTS

Lower plasma apoE3 associated with higher plasma glucose but not insulin in male subjects and subjects with a body mass index above 25. Negative correlations were found between plasma glucose and CMRgl in the left prefrontal and bilateral occipital regions. These associations may have functional implications since glucose levels in turn were negatively associated with neuropsychological test scores.

CONCLUSION

Plasma apoE3 but not apoE4 may be involved in insulin-independent processes governing plasma glucose levels. Higher plasma glucose, which negatively affects brain glucose metabolism, was associated with lower plasma apoE levels in APOE ɛ3/ɛ4 subjects. High plasma glucose and low apoE levels may be a hazardous combination leading to an increased risk of AD.

Association of Apolipoprotein E Polymorphism with Adipokines and Cardiovascular Disease Risk in Rheumatoid Arthritis Patients

Apolipoprotein E (ApoE) polymorphism and adipokines are linked to atherosclerosis. We aimed to investigate the associations of apoE genotypes with adipokines, inflammatory parameters, and cardiovascular disease (CVD) risks in rheumatoid arthritis (RA) patients. We enrolled 152 RA patients and 49 healthy control (HC) subjects. The apoE genotyping was determined by a polymerase chain reaction, while plasma levels of adipokines and inflammatory cytokines were measured with ELISA. Although apoE genotypes distributions were indistinguishable between RA patients and HC, we found significantly higher levels of apoE and adipokines in RA patients compared with HC. RA patients with ε2ε3 genotype had lower levels of TNF-α, IL-6, resistin, and visfatin, but higher leptin levels compared with ε3ε3 genotype patients. Patients with ε3ε4 genotype had significantly higher low-density lipoprotein-cholesterol (LDL-C) levels and atherogenic index scores compared with ε2ε3 genotype carriers. Moreover, patients with ε2ε3 genotype had significantly lower 10-year CVD risk than ε3ε3 or ε3ε4 genotype patients. ε3ε4 genotype and adiponectin levels were independent predictors of a high 10-year CVD risk. RA patients with ε2ε3 genotype are associated with lower levels of TNF-α, IL-6, resistin, visfatin, and CVD risk, while RA patients with ε3ε4 genotype exhibited higher levels of LDL-C, insulin resistance, and higher CVD risks.

APOE2: protective mechanism and therapeutic implications for Alzheimer's disease

Investigations of apolipoprotein E (APOE) gene, the major genetic risk modifier for Alzheimer's disease (AD), have yielded significant insights into the pathogenic mechanism. Among the three common coding variants, APOE*ε4 increases, whereas APOE*ε2 decreases the risk of late-onset AD compared with APOE*ε3. Despite increased understanding of the detrimental effect of APOE*ε4, it remains unclear how APOE*ε2 confers protection against AD. Accumulating evidence suggests that APOE*ε2 protects against AD through both amyloid-β (Aβ)-dependent and independent mechanisms. In addition, APOE*ε2 has been identified as a longevity gene, suggesting a systemic effect of APOE*ε2 on the aging process. However, APOE*ε2 is not entirely benign; APOE*ε2 carriers exhibit increased risk of certain cerebrovascular diseases and neurological disorders. Here, we review evidence from both human and animal studies demonstrating the protective effect of APOE*ε2 against AD and propose a working model depicting potential underlying mechanisms. Finally, we discuss potential therapeutic strategies designed to leverage the protective effect of APOE2 to treat AD.

Apolipoprotein ɛ4 Affects Multiple Domains of Neuropsychological Functioning in a Sample of Elderly Hispanics

Apolipoprotein ɛ4 allele (APOEɛ4) is the strongest genetic risk factor for sporadic Alzheimer's disease (AD), but inconsistencies have arisen in studies with Hispanics. The objective of this study was to explore APOEɛ4 expression and cognitive function in a sample of Panamanian older adults, including healthy controls, mild cognitive impairment, and AD. Participants with at least one copy of APOEɛ4 had a significantly lower performance in global cognition, verbal memory, executive functions, visuospatial abilities, regardless of diagnosis. The present study contributes to the understanding of the association of APOEɛ4 and impairment in specific cognitive domains in elderly Hispanics.

Sex-Dependent Effects of the APOE ɛ4 Allele on Behavioral Traits and White Matter Structures in Young Adults

The APOE ɛ4 allele is associated with a risk of Alzheimer’s disease in the elderly, with the association being pronounced in females. Conversely, findings of the effects of the APOE ɛ4 allele in young adults are mixed. Here, we investigated the sex–genotype interaction effects of the APOE ɛ4 allele on cognitive functions as well as brain structures among 1258 young adults. After adjusting for multiple comparisons, there were significant effects of the interaction between sex and the number of APOE ɛ4 allele on some speed tasks (e.g., simple processing speed tasks and the reverse Stroop task) as well as on regional white matter volume (rWMV). The observed sex–genotype interaction conferred better cognitive performance and greater rWMV in the anterior frontal and precentral white matter areas in females having more APOE ɛ4 alleles and reduced rWMV in the same areas in male having more APOE ɛ4 alleles. These findings support the long-debated antagonistic pleiotropic effects of the APOE ɛ4 allele in females.

Impact of Apo Lipoprotein E Gene Polymorphism on Hepatitis C Virus Disease Progression and Response to Direct Acting Antivirals in the Egyptian Population

Background: Hepatitis C virus infection is a major health problem in Egypt. Apo lipoprotein E and lipid metabolism are closely associated with the life cycle of the virus and play an important role in facilitating this infection. Objectives: To identify the role of apolipoprotein E gene polymorphism on hepatitis C virus disease progression and response to direct-acting antivirals (DAAs). Methods: We included twenty patients with chronic hepatitis C virus infection (CHC) from those who failed to respond to DAAs treatment and 76 subjects from responders. Apo lipoprotein E genotypes were determined using PCR restriction enzyme fragment length polymorphism (RFLP). Results: Apolipoprotein genotype E3/E3 was prevalent in 75.9% of patients. The distribution for the rest of genotypes was 16.9%, 3.6%, 2.4% and 1.2 % for Apo E3/E4, E2/E3, E4/E4, and E2/E2 respectively. No statistically significant difference was found regarding any of the Apo E genotypes with liver cirrhosis or response to therapy. Conclusions: No significant impact for any Apo E genotypes on CHC disease severity or response to therapy with direct-acting antivirals was detected among Egyptian patients.

Beyond the CNS: The many peripheral roles of APOE

Apolipoprotein E (APOE) is a multifunctional protein synthesized and secreted by multiple mammalian tissues. Although hepatocytes contribute about 75% of the peripheral pool, APOE can also be expressed in adipose tissue, the kidney, and the adrenal glands, among other tissues. High levels of APOE production also occur in the brain, where it is primarily synthesized by glia, and peripheral and brain APOE pools are thought to be distinct. In humans, APOE is polymorphic, with three major alleles (ε2, ε3, and ε4). These allelic forms dramatically alter APOE structure and function. Historically, the vast majority of research on APOE has centered on the important role it plays in modulating risk for cardiovascular disease and Alzheimer's disease. However, the established effects of this pleiotropic protein extend well beyond these two critical health challenges, with demonstrated roles across a wide spectrum of biological conditions, including adipose tissue function and obesity, metabolic syndrome and diabetes, fertility and longevity, and immune function. While the spectrum of biological systems in which APOE plays a role seems implausibly wide at first glance, there are some potential unifying mechanisms that could tie these seemingly disparate disorders together. In the current review, we aim to concisely summarize a wide breadth of APOE-associated pathologies and to analyze the influence of APOE in the development of several distinct disorders in order to provide insight into potential shared mechanisms implied in these various pathophysiological processes.

Genetic and epigenetic regulation of human aging and longevity

Here we summarize the latest data on genetic and epigenetic contributions to human aging and longevity. Whereas environmental and lifestyle factors are important at younger ages, the contribution of genetics appears more important in reaching extreme old age. Genome-wide studies have implicated ~57 gene loci in lifespan. Epigenomic changes during aging profoundly affect cellular function and stress resistance. Dysregulation of transcriptional and chromatin networks is likely a crucial component of aging. Large-scale bioinformatic analyses have revealed involvement of numerous interaction networks. As the young well-differentiated cell replicates into eventual senescence there is drift in the highly regulated chromatin marks towards an entropic middle-ground between repressed and active, such that genes that were previously inactive "leak". There is a breakdown in chromatin connectivity such that topologically associated domains and their insulators weaken, and well-defined blocks of constitutive heterochromatin give way to generalized, senescence-associated heterochromatin, foci. Together, these phenomena contribute to aging.

Hidden Aggregation Hot-Spots on Human Apolipoprotein E: A Structural Study

Human apolipoprotein E (apoE) is a major component of lipoprotein particles, and under physiological conditions, is involved in plasma cholesterol transport. Human apolipoprotein E found in three isoforms (E2; E3; E4) is a member of a family of apolipoproteins that under pathological conditions are detected in extracellular amyloid depositions in several amyloidoses. Interestingly, the lipid-free apoE form has been shown to be co-localized with the amyloidogenic Aβ peptide in amyloid plaques in Alzheimer’s disease, whereas in particular, the apoE4 isoform is a crucial risk factor for late-onset Alzheimer’s disease. Evidence at the experimental level proves that apoE self-assembles into amyloid fibrilsin vitro, although the misfolding mechanism has not been clarified yet. Here, we explored the mechanistic insights of apoE misfolding by testing short apoE stretches predicted as amyloidogenic determinants by AMYLPRED, and we computationally investigated the dynamics of apoE and an apoE–Αβ complex. Our in vitro biophysical results prove that apoE peptide–analogues may act as the driving force needed to trigger apoE aggregation and are supported by the computational apoE outcome. Additional computational work concerning the apoE–Αβ complex also designates apoE amyloidogenic regions as important binding sites for oligomeric Αβ; taking an important step forward in the field of Alzheimer’s anti-aggregation drug development.

Association of APOE and CETP TaqIB Polymorphisms with Type 2 Diabetes Mellitus

Apolipoprotein E (APOE) and cholesteryl ester transfer protein (CETP) play an important role in the lipid metabolism. Dyslipidemia is one of the complications that found in type 2 diabetes mellitus (T2DM) patients. The aim of this study was to investigate the association of APOE and CETP TaqIB polymorphisms with T2DM and its related metabolic parameters in Southern Thai population. Study subjects were 241 T2DM patients and 275 healthy controls. The APOE and CETP TaqIB polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. APOE polymorphism showed a statistical difference in allele frequencies (p = 0.025) and genotype distributions (p <0.001) between T2DM patients and healthy controls. The E4 carriers were associated with a significantly higher TC, and/or LDL-C levels compared to the E2 and E3 carriers, respectively in all subjects and healthy controls. Moreover, CETP TaqIB B2B2 genotype was significantly higher HDL-C levels compared with B1B1, and B1B2 genotypes in all subjects, and T2DM patients. Multiple logistic regression analysis showed that APOE and CETP TaqIB polymorphisms were not associated with T2DM. In conclusion, APOE and CETP TaqIB polymorphisms might not be the genetic risk factors for T2DM in Southern Thai population, however, APOE and CETP TaqIB polymorphisms were associated with serum lipids in healthy controls and T2DM, respectively.

Apolipoprotein C-I Polymorphism and Its Association with Serum Lipid Levels and Longevity in the Bama Population

This study aims to determine the association between the apolipoprotein C-I polymorphism and the longevity and genetic variants in ApoC-I that can influence the serum lipid levels in Bama. ApoC-I genotypes were determined by Taqman single nucleotide polymorphism (SNP) genotyping assays in 178 long-lived inhabitants (longevity group aged from 90 to 110 years), 147 healthy controls (Control 1 group aged from 40 to 79 years old) from Bama County, and 190 healthy controls (Control 2 group aged from 40 to 79 years old) from Nandan County without a family history of longevity. Statistical analysis was conducted using SPSS 16.0. All genotype distributions of rs584007 and rs4420638 were consistent with the Hardy-Weinberg equilibrium (p > 0.05). Significant differences were observed in the frequencies of the three genotypes (GG, AG, and AA) among the longevity and the two control groups (χ² = 11.238, p = 0.024) for rs584007. No significant differences were observed in the frequencies of the three genotypes (GG, AG, and AA) among the longevity and the two control groups (χ² = 4.587, p = 0.318) for rs4420638. The levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein-cholesterol (HDL-c), and low-density lipoprotein-cholesterol (LDL-c) were not different among the three genotypes of rs584007 in the three groups. The levels of HDL-c for GG, AG, and AA were significantly different (the highest being in the longevity group), while the levels of TG for AA and AG genotypes (the lowest being in the longevity group) and the levels of LDL-c for AG were significantly different (p < 0.05) among the three groups for rs584007. The levels of TG and HDL-c were significantly different among the three rs4420638 genotypes in the longevity group. The levels of TC for GG, AG, and AA were significantly different in the Control 2 group, while the levels of TG and HDL-c for AA and AG genotypes were significantly different (p < 0.05) among the three groups for rs4420638. The level of HDL-c was highest in the longevity group for AA and AG genotypes, and the level of TG was highest in the Control 2 group for rs4420638. Serum lipid parameters were related to environmental factors, including age, gender, BMI, DBP, SBP, rs4420638, and rs584007. The ApoC-I polymorphism might be one of the genetic factors of longevity in Bama. The ApoC-I rs4420638 and rs584007 SNPs are associated with serum TG and HDL-c levels in the longevous population.

Genomic variants, genes, and pathways of Alzheimer's disease: An overview

Alzheimer's disease (AD) (MIM: 104300) is a highly heritable disease with great complexity in its genetic contributors, and represents the most common form of dementia. With the gradual aging of the world's population, leading to increased prevalence of AD, and the substantial cost of care for those afflicted, identifying the genetic causes of disease represents a critical effort in identifying therapeutic targets. Here we provide a comprehensive review of genomic studies of AD, from the earliest linkage studies identifying monogenic contributors to early-onset forms of AD to the genome-wide and rare variant association studies of recent years that are being used to characterize the mosaic of genetic contributors to late-onset AD (LOAD), and which have identified approximately ∼20 genes with common variants contributing to LOAD risk. In addition, we explore studies employing alternative approaches to identify genetic contributors to AD, including studies of AD-related phenotypes and multi-variant association studies such as pathway analyses. Finally, we introduce studies of next-generation sequencing, which have recently helped identify multiple low-frequency and rare variant contributors to AD, and discuss on-going efforts with next-generation sequencing studies to develop statistically well- powered and comprehensive genomic studies of AD. Through this review, we help uncover the many insights the genetics of AD have provided into the pathways and pathophysiology of AD. © 2016 Wiley Periodicals, Inc.

Variable phenotypic expression of nonsense mutation p.Thr5* in the APOE gene

Subjects with hypercholesterolemia who do not carry a mutation in the low density lipoprotein receptor gene, in the apolipoprotein B gene or in the proprotein convertase subtilisin/kexin type 9 gene, could possible carry a mutation in the apolipoprotein E (APOE) gene. DNA from 844 unrelated hypercholesterolemic subjects who did not carry a mutation in any of the three above mentioned genes, was subjected to DNA sequencing of the APOE gene. Two subjects were found to be heterozygous for mutation p.Thr5*. This mutation which generates a stop codon in the signal peptide, is assumed to prevent the synthesis of APOE. Family studies revealed that the mutation was carried on an APOE4 allele in both families. In one of the families only those who had an APOE2 allele as the second allele, had hypercholesterolemia. These were functionally hemizygous for APOE2 and presented with a Type III hyperlipoproteinemia phenotype. However, in the second family, hypercholesterolemia was observed in the index patient who had APOE3 as the second allele, but not in four heterozygous family members who also had APOE3 as the second allele. These findings underscore that the phenotypic expression of mutations in the APOE gene is variable and that the trait exhibits reduced penetrance.

The Neurobiology and Age-Related Prevalence of the ε4 Allele of Apolipoprotein E in Alzheimer's Disease Cohorts

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterised by amyloid beta (Aβ) plaques and tau neurofibrillary tangles in the brain. Human apolipoprotein E (ApoE) is a lipid transport protein coded by the polymorphic APOE gene, with three major alleles: ε2, ε3 and ε4. After age, the ε4 allele is the greatest risk factor for developing sporadic AD, conferring an increased risk of 3-4 and 8-12 times for one or two copies of the allele, respectively. This risk is reported to vary by demographic factors including sex, ethnicity and geography. In order to understand the risk of ApoE ε4 in relation to age, the primary risk factor for developing AD, we need to understand how the prevalence of APOE genotypes changes with age. Here, we present the first data on age-related prevalence of APOE ε4 in AD in three AD cohorts in Australia and the USA. There is a significant association between age and ε4 prevalence, particularly for ε4 homozygotes, such that as age increases the prevalence of ε4 decreases. Further studies on a random, population-based sample of the population are needed to provide more generalizable data, particularly in the >90-year-old age group.

Olfactory Dysfunction in ApoE ɛ4/4 Homozygotes with Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory impairment and the presence of amyloid plaques and neurofibrillary tangles. The associated neuropathology originates in brain areas responsible for olfaction, which makes olfactory tasks potentially useful for assessing AD. The strongest genetic risk factor for AD is the apolipoprotein E (ApoE) ɛ4 allele that has been associated with increased cognitive and olfactory deficits. While individuals carrying one ɛ4 allele of the ApoE gene are at increased risk for AD relative to non-carriers, those with two copies of the ɛ4 allele demonstrate an even higher risk for developing AD. Furthermore, homozygous ApoE ɛ4/4 individuals diagnosed with AD are known to have heightened amyloid burden and a more rapid rate of cognitive decline relative to heterozygous ɛ3/4 ApoE carriers. All of these factors suggest there are differences in severity and progression of AD as a function of possessing one versus two ɛ4 alleles. The current study investigated olfactory functioning in homozygous ɛ4/4 older adults diagnosed with probable AD. Compared to demographically matched ɛ3/3 and ɛ3/4 individuals, ɛ4/4 individuals showed deficits in odor identification and remote odor memory as measured by odor familiarity ratings. The current findings suggest that these particular domains of olfactory functioning may be more impaired in AD ɛ4/4 homozygotes compared to ɛ3/4 heterozygotes and ɛ3/3 homozygotes. These deficits give insight into how the presence of two ɛ4 alleles may differentially affect the progression of AD and suggest the usefulness of odor tasks in detecting those at risk for AD.

APOE gene polymorphism analysis in Barranquilla, Colombia

INTRODUCTION

The genetic variability present in the APOE gene polymorphism is considered an important factor associated with predisposition to diseases affecting lipid metabolism, as well as heart diseases and Alzheimer's disease, among others. Understanding it as a risk factor in different populations and ethnic groups is a useful tool. 

OBJECTIVE

To analyze the APOE gene polymorphism and determine allelic and genotypic frequencies of a representative sample of population from Barranquilla, Colombia. 

MATERIALS AND METHODS

We performed a descriptive and comparative study. The sample size was 227 unrelated individuals from Barranquilla, Colombia. 

RESULTS

The most frequent allele was the ε3, with 85%, followed by the ε4 allele (13%) and ε2 (1.8%). The genotypes found were: ε3/ε3: 71.8%, ε3/ε4: 24.2%, ε2/ε3: 2.2%, ε2/ε4: 1.3% and ε4/ε4: 0.4%. The ε2/ε2 genotype was not found in this study. The sample exhibited the Hardy-Weinberg equilibrium. 

CONCLUSION

The frequency of the ε3 allele and the ε3/ε3 genotype was similar to that reported in the literature in countries like Brazil, Mexico, Colombia, and in some Colombian Amerindian ethnic groups. The ε2/ε2 genotype was absent. This result is consistent with those found in other population groups worldwide. The frequency of the ε4 allele and the genotypes associated in this population could be related to the presence of diseases such as hypercholesterolemia, myocardial infarction and Alzheimer.

A rapid and cost-effective method for genotyping apolipoprotein E gene polymorphism

Background

Apolipoprotein E (ApoE) is a major cholesterol carrier and plays an important role in maintaining lipid homeostasis both in the periphery and brain. Human APOE gene is polymorphic at two single nucleotides (rs429358 and rs7412) resulting in three different alleles (ε2, ε3 and ε4). ApoE isoforms modulate the risk for a variety of vascular and neurodegenerative diseases; thus, APOE genotyping is crucial for predicting disease risk and designing individualized therapy based on APOE genotype.

Results

We have developed an APOE genotyping method that is based on allele-specific PCR methodology adapted to Real Time PCR monitored by TaqMan probe. Rather than using TaqMan probes specific for the two polymorphic sites, only one TaqMan probe is used as the polymorphic alleles are recognized by site-specific PCR primers. Each genotyping assay can be completed within 90 minutes and is applicable to high-throughput analysis. Using this protocol, we genotyped a total of 1158 human DNA samples and obtained a 100 % concordance with the APOE genotype determined by sequencing analysis.

Conclusion

The APOE genotyping assay we have developed is accurate and cost-effective. In addition, our assay can readily be applied to genotyping large sample numbers. Therefore, our APOE genotyping method can be used for assessing the risk for a variety of vascular and neurodegenerative diseases that have been reported to be associated with APOE polymorphism.

Association between APOE polymorphism and metabolic syndrome in Uyghur ethnic men

OBJECTIVES

This study aimed to examine the association between apolipoprotein E (APOE) polymorphism and metabolic syndrome (MetS) among Uyghur ethnic men in Xinjiang, China.

PARTICIPANTS

A total of 482 patients with MetS and 510 healthy sex-matched and age-matched controls were recruited from the Xinjiang Uyghur Autonomous Region of China. The participants were subjected to routine physical and blood biochemical tests, and APOE genotyping was performed.

RESULTS

The APOE ε3/3 was the predominant type, with a frequency of 71.8%, while ε2/2 was less common than ε4/4 in Uyghur males. The frequencies of the APOE2, E3 and E4 alleles in Uyghur males were 8.5%, 80.0% and 11.5%, respectively. However, the distribution of APOE genotypes was significantly different between the MetS and control groups (p<0.001). In the MetS group, the frequencies of the ε2 and ε4 alleles and the frequencies of the ε2/2, ε2/3 and ε2/4 genotypes were significantly lower than those of the control group. Those individuals without the ε2 and ε4 alleles had higher MetS prevalence than the other gene carriers, and the ORs of these individuals developing MetS were 1.5 and 1.27 compared to the gene carriers. Triglyceride, serum total cholesterol and low-density lipoprotein cholesterol levels were lower and serum high-density lipoprotein was higher in the ε2 carriers than the ε3 carriers, and the prevalence of MetS, central obesity, high blood pressure, hypercholesterolaemia and hypertriglyceridaemia was lower in the APOE2 group than in the APOE4 group. The risks of these individuals with ε4 allele carriers getting these changes were 1.327, 1.780, 1.888, 1.428 and 2.571 times greater than those of ε2 allele carriers.

CONCLUSIONS

APOE4 is associated with many individual components of MetS, whereas APOE2 was associated with a reduced risk of MetS at the univariate level in Uyghur ethnic men.

Amplification refractory mutation system polymerase chain reaction versus optimized polymerase chain reaction restriction-fragment length polymorphism for apolipoprotein E genotyping of majorly depressed patients

Major depressive disorder (MDD) is a prevalent, debilitating mood disorder that has been associated with several genetic polymorphisms. One such polymorphism, namely that of apolipoprotein E (APOE), has three allelic forms (ε2, ε3 and ε4) that encode for six unique isoforms of the APOE protein. A growing number of techniques have been developed for APOE genotyping; however, not all polymerase chain reaction (PCR)‑based genotyping techniques are equally accurate or cost‑effective. In order to find a more accurate and cost‑effective APOE genotyping method for MDD screening in large populations, the present study comparatively evaluated two genotyping methods, amplification refractory mutation system PCR (ARMS‑PCR) and optimized PCR restriction‑fragment length polymorphism (PCR‑RFLP), in blood samples taken from a population of 708 MDD patients. Although either of the two methods were able to detect all six unique APOE genotypes, comparisons of the two methods with Sanger sequencing demonstrated that ARMS‑PCR (94%) was significantly more accurate than optimized PCR‑RFLP (82%). ARMS‑PCR should prove useful in quickly verifying ambiguous results obtained by other APOE genotyping methods and can be cost-effectively performed in the setting of a small laboratory or a population-based screening program.

Association of apolipoprotein E (ApoE) polymorphisms with risk of primary hyperuricemia in Uygur men, Xinjiang, China

BACKGROUND

Apolipoprotein E (ApoE) participates in lipoprotein metabolism and immune regulation. This study assessed association between ApoE polymorphisms with hyperuricemia and uric acid metabolism in Uygur men, Xinjiang, China.

METHODS

A total of 474 hyperuricemia patients and 518 healthy male controls were recruited from the Health Screening Center, Uygur region of Xinjiang, China and subjected to ApoE genotyping using a multiplex amplification refractory mutation system PCR.

RESULTS

Apolipoprotein E3/3 genotype was the predominant type with a frequency of 67.7%, while E2/2 was lower than E4/4 in Uygur males. The frequencies of ApoE2, E3, and E4 alleles were 8.5%, 80.1% and 11.4%, respectively. Distribution of ApoE genotypes was significantly different in hyperuricemia patients from the healthy controls (p<0.001). Particularly, the frequency of ApoE E3/3 was 71.7%, E2/3 9.3%, E3/4 9.3%, E4/4 3.2%, E2/4 2.3%, and E2/2 0.2% in patients vs. 68.1%, 4.6%, 2.9%, 12%, 0.6%, and 4.6% in controls, respectively. Moreover, frequency of ApoE E2 allele was greater in the healthy controls than in patients (p<0.001) and the highest level of uric acid occurred in those with ApoE2/4 and E3/4 genotypes, whereas the lowest uric acid level occurred in those with ApoE E2/2 genotype. In addition, the subjects with the ApoE2 allele had a lower uric acid and LDL-C level than those with the ApoE3 allele and ApoE4 allele (p<0.05). The risk of developing hyperuricemia in subjects without the ApoE2 allele was 1.7 fold higher than those subjects with the ApoE2 allele.

CONCLUSIONS

This study revealed frequencies and distributions of ApoE alleles and genotypes in Uygur males, which are different from Han Chinese. ApoE E4 was associated with a slightly higher risk of primary hyperuricemia, whereas ApoE E2 was associated with reduced risk of primary hyperuricemia and LDL-C level.

Genetic Variation of ApoE Gene in Ethnic Kashmiri Population and Its Association with Outcome After Traumatic Brain Injury

The outcome from traumatic brain injury (TBI) is variable and only partly explained by known prognostic factors. Genetic factors may influence the brain's susceptibility to injury or capacity for repair and regeneration. ApoE has been implicated in modifying neurological outcome after TBI, although the mechanisms by which this occurs remain poorly defined. Apolipoprotein E is an apparently multifunctional protein involved in the response of the brain to injury and in subsequent repair processes. Several studies have shown that patients with APOE e4 have a poorer outcome after TBI. This study was aimed to analyse the genotypes of ApoE in Kashmiri population and to examine the association of APOE genotype with outcome after TBI. A total of 450 subjects (300 healthy controls and 150 TBI patients) were recruited for the study. Genotyping was done by PCR-restriction fragment length polymorphism (RFLP).Our study indicated Apoe3/e3 to be the most common genotype in this study group. The allele frequency of the Apo E gene in these study subjects was observed to be 0.07 for the e2 allele, 0.82 for the e3 allele and 0.11 for the e4 allele. However, no association between the presence of APOe4 allele and outcome after head injury was observed in this study [p = 0.92]. Thus, genotype containing the e4 allele (e4/e3 and e4/e4) was not associated with unfavourable outcome after TBI in Kashmiri population.

Comprehensive evaluation of the association of APOE genetic variation with plasma lipoprotein traits in U.S. whites and African blacks

Although common APOE genetic variation has a major influence on plasma LDL-cholesterol, its role in affecting HDL-cholesterol and triglycerides is not well established. Recent genome-wide association studies suggest that APOE also affects plasma variation in HDL-cholesterol and triglycerides. It is thus important to resequence the APOE gene to identify both common and uncommon variants that affect plasma lipid profile. Here, we have sequenced the APOE gene in 190 subjects with extreme HDL-cholesterol levels selected from two well-defined epidemiological samples of U.S. non-Hispanic Whites (NHWs) and African Blacks followed by genotyping of identified variants in the entire datasets (623 NHWs, 788 African Blacks) and association analyses with major lipid traits. We identified a total of 40 sequence variants, of which 10 are novel. A total of 32 variants, including common tagSNPs (≥5% frequency) and all uncommon variants (<5% frequency) were successfully genotyped and considered for genotype-phenotype associations. Other than the established associations of APOE*2 and APOE*4 with LDL-cholesterol, we have identified additional independent associations with LDL-cholesterol. We have also identified multiple associations of uncommon and common APOE variants with HDL-cholesterol and triglycerides. Our comprehensive sequencing and genotype-phenotype analyses indicate that APOE genetic variation impacts HDL-cholesterol and triglycerides in addition to affecting LDL-cholesterol.

Target-responsive DNA-capped nanocontainer used for fabricating universal detector and performing logic operations

Nucleic acids have become a powerful tool in nanotechnology because of their controllable diverse conformational transitions and adaptable higher-order nanostructure. Using single-stranded DNA probes as the pore-caps for various target recognition, here we present an ultrasensitive universal electrochemical detection system based on graphene and mesoporous silica, and achieve sensitivity with all of the major classes of analytes and simultaneously realize DNA logic gate operations. The concept is based on the locking of the pores and preventing the signal-reporter molecules from escape by target-induced the conformational change of the tailored DNA caps. The coupling of 'waking up' gatekeeper with highly specific biochemical recognition is an innovative strategy for the detection of various targets, able to compete with classical methods which need expensive instrumentation and sophisticated experimental operations. The present study has introduced a new electrochemical signal amplification concept and also adds a new dimension to the function of graphene-mesoporous materials hybrids as multifunctional nanoscale logic devices. More importantly, the development of this approach would spur further advances in important areas, such as point-of-care diagnostics or detection of specific biological contaminations, and hold promise for use in field analysis.

Apolipoprotein E genotyping in women with recurrent pregnancy loss: an in silico and experimental hybrid study

The role of apolipoprotein E gene polymorphisms in the pathogenesis of recurrent pregnancy loss remains controversial. Therefore, our objective was to investigate the association between recurrent pregnancy loss and apolipoprotein E gene polymorphisms among northwest Iranian women, and also to predict the impact of these nonsynonymous single nucleotide polymorphisms on structure and function of apolipoprotein E protein. The subjects of our current study consisted of 100 women that have had two or more consecutive idiopathic first trimester miscarriages, and one hundred healthy women from the same geographical areas were used as a control group. After DNA extraction, we used a polymerase chain reaction-restriction fragment length polymorphism to genotype of the apolipoprotein E gene. In addition, we predicted the possible effects of amino acid substitutions at codons 112 and/or 158 on the structure and function of apolipoprotein E protein using Polymorphism Phenotyping online software v2. Our results showed that the rate of apolipoprotein E ε4 carriers and the frequency of the ε4 allele in the case group were statistically and significantly higher than those in the control group (P<0.05). Therefore, our data support the association of the Apo ε4 allele with RPL; however, in silico analysis predicted that the amino acid substitution at residue 112 (Apo ε4 allele) is a benign mutation. Accordingly, further studies are required to elucidate the mechanism(s) underlying the link between RPL pathogenesis and the Apo ε4 allele.

Primary genetic investigation of a hyperlipidemia model: molecular characteristics and variants of the apolipoprotein E gene in Mongolian gerbil

The objective of this work was to establish a novel Mongolian gerbil (Meriones unguiculatus) hyperlipidemia model and to investigate its susceptibility genetic basis. Two rodent (gerbil and rat) hyperlipidemia models were induced by feeding a high fat/high-cholesterol (HF/HC) diet. There were significant increases of serum total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) in gerbils within a 4-week modeling period. About 10–30% of >8-month-old individuals developed hyperlipidemia spontaneously. The apolipoprotein E (ApoE) gene was cloned by merging a sequence of rapid amplification of cDNA ends (RACE) and nested polymerase chain reaction products. The results revealed an open reading frame of 948 bp, encoding a protein of 298 amino acids. The gene without a 5′-UTR region in the first intron was highly homologous to human Apo-A-I and rat Apo-A-IV. The distribution of expression of the ApoE gene in liver, brain, heart, lung, kidney, and adrenal gland was detected by an ABC immunohistochemical procedure. Three single nucleotide polymorphisms (SNPs; C97T, G781T, and A1774T) were first found using PCR-single-strand conformation polymorphism (PCR-SSCP) in a closed population containing 444 animals. Correlation analysis confirmed that new SNPs , age, and gender were associated significantly (P < 0.05) with hyperlipidemia.

Genetic studies in human prion diseases

Human prion diseases are fatal neurodegenerative disorders that are characterized by spongiform changes, astrogliosis, and the accumulation of an abnormal prion protein (PrP(Sc)). Approximately 10%-15% of human prion diseases are familial variants that are caused by pathogenic mutations in the prion protein gene (PRNP). Point mutations or the insertions of one or more copies of a 24 bp repeat are associated with familial human prion diseases including familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome, and fatal familial insomnia. These mutations vary significantly in frequency between countries. Here, we compare the frequency of PRNP mutations between European countries and East Asians. Associations between single nucleotide polymorphisms (SNPs) of several candidate genes including PRNP and CJD have been reported. The SNP of PRNP at codon 129 has been shown to be associated with sporadic, iatrogenic, and variant CJD. The SNPs of several genes other than PRNP have been showed contradictory results. Case-control studies and genome-wide association studies have also been performed to identify candidate genes correlated with variant and/or sporadic CJD. This review provides a general overview of the genetic mutations and polymorphisms that have been analyzed in association with human prion diseases to date.

Impact of APOE gene polymorphisms on the lipid profile in an Algerian population

Background

The importance of apolipoprotein E (APOE) in lipid and lipoprotein metabolism is well established. However, the impact of APOE polymorphisms has never been investigated in an Algerian population. This study assessed, for the fist time, the relationships between three APOE polymorphisms (epsilon, rs439401, rs4420638) and plasma lipid concentrations in a general population sample from Algeria.

Methods

The association analysis was performed in the ISOR study, a representative sample of the population living in Oran (787 subjects aged between 30 and 64). Polymorphisms were considered both individually and as haplotypes.

Results

In the ISOR sample, APOE ϵ4 allele carriers had higher plasma triglyceride (p=0.0002), total cholesterol (p=0.009) and LDL-cholesterol (p=0.003) levels than ϵ3 allele carriers. No significant associations were detected for the rs4420638 and rs439401 SNPs. Linkage disequilibrium and haplotype analyses confirmed the respectively deleterious and protective impacts of the ϵ4 and ϵ2 alleles on LDL-cholesterol levels and showed that the G allele of the rs4420638 polymorphism may exert a protective effect on LDL-cholesterol levels in subjects bearing the APOE epsilon 4 allele.

Conclusion

Our results showed that (i) the APOE epsilon polymorphism has the expected impact on the plasma lipid profile and (ii) the rs4420638 G allele may counterbalance the deleterious effect of the ϵ4 allele on LDL-cholesterol levels in an Algerian population.

Apolipoprotein ε4-allele as a significant risk factor for conversion from mild cognitive impairment to Alzheimer's disease: a meta-analysis of prospective studies

Recent studies of the relationship between progression from mild cognitive impairment (MCI) to Alzheimer disease (AD) and APOE ε4-allele revealed inconsistent results. To estimate the risk posed by APOE ε4-allele for developing AD in MCI subjects using meta-analysis and identify possible sources of heterogeneity between studies, we reviewed longitudinal epidemiological studies of the presence of APOE ε4-allele on risk for progression to dementia in MCI subjects, and conducted meta-analyses of the results from these studies. Our study was derived from 315 positive-outcome events and 461 negative-outcome events from 8 prospective studies. The pooled RR was statistically significant (pooled RR = 2.09; 95 % CI, 1.52-2.88). The Q statistics indicated high heterogeneity across studies (Q = 14.21, p = 0.003). RR were significantly related to the ethnicity of the sample (z = 3.58, p = 0.024). No significant heterogeneity was observed after stratification in four European-population studies (χ² = 0.67, p = 0.880), but it remained in four American-population studies (χ² = 18.52, p = 0.003). Heterogeneity markedly reduced after excluding one specific study (Q = 4.9, p = 0.009; I² = 39 %). APOE ε4-allele conferred increased risk for progression to dementia in MCI subjects. Ethnicity is a critical factor to yield heterogeneity. Further studies using larger sample sizes are required.

Distribution and effect of apo E genotype on plasma lipid and apolipoprotein profiles in overweight/obese and nonobese Chinese subjects

BACKGROUND

Apolipoprotein E (apo E) polymorphism has been reported to influence some lipid profile abnormalities in some ethnic groups. This study was conducted mainly to examine the possible association of apo E polymorphism with overweight/obesity in a South West Chinese population.

METHODS

Four hundred and fifty-four Han Chinese (282 overweight/obese and 172 normal weight control subjects) in Chengdu area were studied using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

The genotype and allele frequencies of apo E polymorphism in cases of overweight/obesity showed no significant statistical difference compared to those of controls. In the control group, both apo E4 and E3 allele carriers had the higher serum LDL-C and lower triglycerides (TGs) and apo E concentrations than those with apo E2 carriers, while apo E2 allele carriers had higher serum apo C-II levels than apo E3 carriers (P < 0.05). In overweight/obese group, genotype-related low density Lipoprotein-Cholesterol (LDL-C) variations were also evident, with the changes being in a same direction as the effect in the controls, and apo B100 levels were decreased and apo E increased in apo E2 allele carriers when compared with respective apo E4 and apo E4/apo E3 allele carriers (all P < 0.05).

CONCLUSION

Polymorphism of the apo E gene is associated with altered plasma LDL-C and TG, as well as apo B, apo C-II, and apo E concentrations. The effects on TG, apo B, and apo C-II levels are BMI dependent in Chinese population of Chengdu area.

Expression analysis, single nucleotide polymorphisms and combined genotypes in candidate genes and their associations with growth and carcass traits in Qinchuan cattle

The apolipoprotein E (ApoE) gene is an important component of plasma lipoprotein, and Fas apoptosis inhibitory molecule (FAIM) is a novel anti-apoptotic gene. In this study, we researched and discussed seven genes in eight different tissues in Qinchuan cattle by quantitative Real-time PCR. The result of analysis showed that ApoE and FAIM 2 genes had a correlation with muscle and fat. PCR-RFLP was applied to analyze the genetic variations of the ApoE and FAIM 2 genes and verify the effect on growth and carcass traits in a total of 365 Qinchuan cattles. The result of haplotype analysis showed that nine different haplotypes were identified among the four SNPs in ApoE and FAIM 2 genes. The statistical analyses indicated that the four SNPs were significant association with growth and carcass traits (P < 0.05, N = 365); and the four SNPs were significant association between nine combined genotypes of candidate genes and growth and carcass traits. Taken together, our results provide the evidence that polymorphisms in candidate genes are associated with growth and carcass traits in Qinchuan cattle, and may be used as a possible candidate for marker-assisted selection and management in beef cattle breeding program.

Gene-environment interaction in Alzheimer's disease

OBJECTIVES

The aim was to examine the gene environment (GxE) interaction with reference to APO E genotypes, serum lipids and organochlorine pesticides (OCPs) as one of the factors in the etiology of Alzheimer's disease (AD).

METHODS

A case control study was used to examine, APOE HhaI polymorphism by polymerase chain reaction (PCR)/PCRrestriction fragment length polymorphism method, serum lipids by autoanalyser and OCPs by gas chromatography (GC).

RESULTS

APOE ∈4 allele frequency was significantly high (p=0.000, OR=5.73, CI=2.68-12.50) in AD as compared to controls. The serum cholesterol, β- hexachlorocyclohexane and dieldrin are risk factors for AD independent of the APOE ∈4 risk allele, recording an odds ratio of 1.16, 11.38 and 10.45 respectively.

CONCLUSION

GxE interactions exist with APOE ∈4 allele status that need to be considered for the study design and analysis of such data in future studies of AD.

Nucleic acid functionalized graphene for biosensing

There is immense demand for complex nanoarchitectures based on graphene nanostructures in the fields of biosensing or nanoelectronics. DNA molecules represent the most versatile and programmable recognition element and can provide a unique massive parallel assembly strategy with graphene nanomaterials. Here we demonstrate a facile strategy for covalent linking of single stranded DNA (ssDNA) to graphene using carbodiimide chemistry and apply it to genosensing. Since graphenes can be prepared by different methods and can contain various oxygen containing groups, we thoroughly investigated the utility of four different chemically modified graphenes for functionalization by ssDNA. The materials were characterized in detail and the different DNA functionalized graphene platforms were then employed for the detection of DNA hybridization and DNA polymorphism by using impedimetric methods. We believe that our findings are very important for the development of novel devices that can be used as alternatives to classical techniques for sensitive and fast DNA analysis. In addition, covalent functionalization of graphene with ssDNA is expected to have broad implications, from biosensing to nanoelectronics and directed, DNA programmable, self-assembly.

Detection of DNA hybridization on chemically modified graphene platforms

The increasing demand for simple, low-cost, rapid, sensitive and label-free methods for the detection of DNA sequences and the presence of single nucleotide polymorphisms (SNPs) has become an important issue in biomedical research. In this work, we studied the performances of several chemically modified graphene nanomaterials as sensing platforms by using the electrochemical impedance spectroscopy technique for the detection. We employed a hairpin DNA as a highly selective probe for the detection of SNP correlated to Alzheimer's disease. We believe that our findings may present a foundation for further research and development in graphene-based impedimetric biosensing.

The modulating effect of mechanical changes in lipid bilayers caused by apoE-containing lipoproteins on Aβ induced membrane disruption

A major feature of Alzheimer's disease (AD), a late-onset neurodegenerative disorder, is the ordered aggregation of the β-amyloid peptide (Aβ) into fibrils that comprise extracellular neuritic plaques found in the disease brain. One of many potential pathways for Aβ toxicity may be modulation of lipid membrane function. Here, we show by in situ atomic force microscopy (AFM) that astrocyte secreted lipoprotein particles (ASLPs) containing different isoforms of apolipoprotein E (apoE), of which the apoE4 allele is a major risk factor for the development of AD, can protect total brain lipid extract bilayers from Aβ(1-40) induced disruption. The apoE4 allele was less effective in protecting lipid bilayers from disruption compared with apoE3. Size analysis of apoE-containing ASLPs and mechanical studies of bilayer properties revealed that apoE-containing ASLPs modulate the mechanical properties of bilayers by acquiring some bilayer components (most likely cholesterol and/or oxidatively damaged lipids). Measurement of bilayer mechanical properties was accomplished with scanning probe acceleration microscopy (SPAM). These measurements demonstrated that apoE4 was also less effective in modulating mechanical properties of bilayers in comparison with apoE3. This ability of apoE to alter the mechanical properties of lipid membranes may represent a potential mechanism for the suppression of Aβ(1-40) induced bilayer disruption.

Molecular genetic epidemiology of age-related hearing impairment

Genetic epidemiology focuses on the genetic determinants in the etiology of disease among populations and seeks to elucidate the role of genetic factors and their interaction with environmental factors in disease occurrence. In recent years, genetic epidemiological research has become more focused on complex diseases, and human genome analysis technology has made remarkable advances. Age-related hearing impairment (ARHI) is a complex trait, which results from a multitude of confounding intrinsic and extrinsic factors. Although the number of genetic investigations of ARHI is increasing at a surprising rate, the etiology of ARHI is not firmly established. In this article, we review (1) the methodological strategies used to analyze genetic factors that contribute to human ARHI, (2) several representative investigations, and (3) specific genetic risk factors for human ARHI identified in previous work.