The relationship of APOE genetic polymorphism with susceptibility to multiple sclerosis and its clinical phenotypes in Kuwaiti Arab subjects

Association between apolipoprotein E gene polymorphism and the risk of multiple sclerosis: a meta-analysis of 6977 subjects

Epidemiological studies have evaluated the association between apolipoprotein E (ApoE) gene polymorphism and multiple sclerosis (MS) risk. However, the results remain conflicting. Therefore, in order to derive a more precise association of ApoE gene polymorphism with MS risk, we performed this meta-analysis. Systematic searches of electronic databases PubMed, Embase and Web of Science, as well as hand searching of the references of identified articles were performed. Twenty studies were identified, covering a total of 4080 MS cases and 2897 controls. The results showed evidence for significant association between ApoE ε2 mutation and MS risk (for ε2/ε4 versus ε3/ε3: OR=1.74, 95% CI=1.12-2.71, p=0.01; for ε2 allele versus ε3 allele: OR=1.16, 95% CI=1.01-1.35, p=0.04). In the subgroup analysis by ethnicity, the similar results were obtained among Europeans (for ε2/ε4 versus ε3/ε3: OR=1.81, 95% CI=1.14-2.87, p=0.01; for ε2 allele versus ε3 allele: OR=1.19, 95% CI=1.02-1.38, p=0.03). After excluding the outlier studies by observing Galbraith plot, marginal association was found between ApoE ε3/ε4 genotype and the protective factor for MS (for ε3/ε4 versus ε3/ε3: OR=0.86, 95% CI=0.75-0.99, p=0.04). In summary, the present meta-analysis provides evidence that ApoE ε2 mutation is associated with MS risk. In addition, ApoE ε3/ε4 genotype appears to be a protective factor for MS.

Peroxisome proliferator-activated receptor and age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of new blindness in the western world and is becoming more of a socio-medical problem as the proportion of the aged population increases. There are multiple efforts underway to better understand this disease process. AMD involves the abnormal retinal pigment epithelium (RPE), drusen formation, photoreceptor atrophy, and choroidal neovascularization. Peroxisome proliferator-activated receptors (PPARs) play an important role in lipid degeneration, immune regulation, regulation of reactive oxygen species (ROSs), as well as regulation of vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9), and docosahexaenoic acid (DHA). These molecules have all been implicated in the pathogenesis of AMD. In addition, PPAR gamma is expressed in RPE, an essential cell in photoreceptor regeneration and vision maintenance. This review summarizes the interactions between PPAR, AMD-related molecules, and AMD-related disease processes.

The immune-modulatory role of apolipoprotein E with emphasis on multiple sclerosis and experimental autoimmune encephalomyelitis

Apolipoprotein E (apoE) is a 34.2 kDa glycoprotein characterized by its wide tissue distribution and multiple functions. The nonlipid-related properties of apoE include modulating inflammation and oxidation, suppressing T cell proliferation, regulating macrophage functions, and facilitating lipid antigen presentation by CD1 molecules to natural killer T (NKT) cells, and so forth. Increasing studies have revealed that APOE ε allele might be associated with multiple sclerosis (MS), although evidence is still not sufficient enough. In this review, we summarized the current progress of the immunomodulatory functions of apoE, with special focus on the association of APOE ε allele with the clinical features of MS and of its animal model experimental autoimmune encephalomyelitis (EAE).

The genetics of clinical outcome in multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system (CNS), the clinical course of which varies considerably between patients. Genetic complexity and interactions with as yet unknown environmental factors have hindered researchers from fully elucidating the aetiology of the disease. In addition to influencing disease susceptibility, epidemiological evidence suggests that genetic factors may affect phenotypic expression of the disease. Genes that affect clinical outcome may be more effective therapeutic targets than those which determine susceptibility. We present in this review a comprehensive survey of the genes (both MHC- and non-MHC-related) that have been investigated for their role in disease outcome in MS. Recent studies implicating the role of the genotype and epistatic interactions in the MHC in determining outcome are highlighted.

Apolipoprotein E genotype does not associate with disease severity measured by Multiple Sclerosis Severity Score

OBJECTIVES

During the last years, the association between apolipoprotein E (APOE) polymorphism and disease severity in multiple sclerosis (MS) has been studied with conflicting results. As a result of a considerable individual variation in the clinical course of MS, there is no consensus method for measuring progression using single assessments of disability. Recently, Multiple Sclerosis Severity Score (MSSS) method has been proposed for comparing disease progression using single data. We evaluate in our population if there is any correlation between APOE genotype and severity according to MSSS.

METHODS

We studied 82 patients followed up in our Neurology Unit throughout the year 2005, diagnosed with MS, and with disease duration of at least 2 years. We collected data concerning demographic and clinical variables including age of onset, disease duration, Expanded Disability Status Scale (EDSS) score and the total number of relapses. When reached, we determined the latency to EDSS scores of 4.0 and 6.0. We calculated progression index (PI) and relapse rate (RR). We ascertained MSSS for our patients in the global MSSS table.

RESULTS

We found four patients heterozygous for the E2 allele and 16 for the E4 allele. No patient was homozygous for E2 or E4. RR (P = 0.017 with 95% CI: 0.005-0.57) and PI (P = 0.016 with 95% CI: 0.004-0.38) were significantly lower in E4 carriers. MSSS scores were not associated with carriership of E2 or E4.

CONCLUSION

Our results show no effect of the APOE genotype on the severity of MS measured by MSSS, as a recently published meta-analysis has noticed. So, our data do not support a role for APOE in MS severity, in spite of the seeming influence shown using other measures such as PI. MSSS is probably the best method to measure severity with a single measure of disability and should be used more frequently when performing genetic research.

Recent advances in genetic analysis of multiple sclerosis: genetic associations and therapeutic implications

Epidemiological studies have confirmed that genetic factors are a key component in the pathogenesis of multiple sclerosis (MS) and that those determining MS susceptibility have been extensively studied. Many papers have been published regarding the heritable differences useful in genetic studies; these include variations in DNA, such as single-nucleotide polymorphisms, microsatellites and insertion/deletion polymorphisms. However, to date, among other regions, HLA is the only region confirmed to possess genes that determine MS susceptibility. In this article, we review the progress during the last 5 years in the studies on the susceptibility genes and the pharmacogenetics of MS. Newer techniques and methods of analysis will hopefully result in better screening of individuals who are at highest risk and novel treatments.

Apolipoprotein E gene polymorphism and allele frequencies in the Lebanese population

Apolipoprotein E (ApoE) genotypes were studied in order to determine the prevalence in the Lebanese population and compare it with other populations. DNA from 160 unrelated healthy donors from our HLA-bank was used. ApoE genotype was determined using the CardioVascular Disease (CVD) StripAssay (this assay is based on a Polymerase Chain Reaction-Reverse Hybridization technique). The prevalence of genotypes E3/3, E3/4, and E2/3 was found to be 69%, 26%, and 22%, respectively, and 0.6% for each of E2/4 and E4/4 genotypes. The Lebanese population tested showed similarities to earlier reported ApoE genotypic distributions (high E3 allele frequency) but also peculiar differences especially to some Arabic countries (total absence of E2 allele among Saudis) and other populations. This is the first report from Lebanon that will serve as a template for future investigations of the prevalence of ApoE alleles in association with various clinical entities.

The association between apolipoprotein E and multiple sclerosis

The article is a complete literature study that investigates the association between apolipoprotein E (Apo E) and multiple sclerosis (MS). Apo E is an important factor in transport, uptake, and redistribution of cholesterol, which is significant to remodelling and repair of nerve tissue. Apo E is involved in neurodegenerative diseases and the most well known association is between Apo epsilon4 and Alzheimer's disease. Only one study found that homozygosity for Apo epsilon4 does cause an increased risk of developing MS. No results indicate that heterozygosity for Apo epsilon4 causes a greater risk of developing MS. No association between the Apo epsilon4 allele and MS subgroups, age of onset, and gender has been found. The association between Apo epsilon4 and relapse rate is contradictory. Most results confirm the hypothesis about an association between the Apo epsilon4 allele and increased disease progression. Two longitudinal studies found an association between Apo epsilon4 and increased disease progression. Half of the cross-sectional studies found the same association. Four of seven published studies examining the association between Apo epsilon4 and increased disease progression using magnetic resonance imaging (MRI) found a significant association. Apo epsilon4 appears to be a predisposing factor to a faster disease progression in MS.

The impact of our genes: consequences of the apolipoprotein E polymorphism in Alzheimer disease and multiple sclerosis

Epidemiological studies provide strong evidence that susceptibility to multiple sclerosis (MS) is in part genetically determined. Likewise the heterogeneity in clinical manifestations, temporal course, severity, and in the pathological processes of MS are probably also influenced by our genes. Apolipoprotein E (apoE) polymorphism has been considered a candidate for impacting on MS because of its numerous functions related to brain tissue and evidence for an association with a variety of cerebral disorders, specifically Alzheimer's disease (AD). The apoE alleles epsilon2, epsilon3, and epsilon4 are known to impact differently on aspects such as neuronal growth and repair, neuroprotection and inflammation. After a review of the strong association of the apoE polymorphism with AD, we review the results on MS. These are far less homogenous but have gained support from morphologic and metabolic measures obtained with magnetic resonance imaging indicating a greater extent of brain destruction with the apoE epsilon4 allele. Evidence for a protective role of the epsilon2 allele in MS is weak. In view of the association with AD it is tempting to speculate that neuropsychologic functioning in MS might be even more strongly related to the apoE polymorphism and especially to the epsilon4 allele than other deficits, but few data on this issue are yet available. While part of the association of the apoE polymorphism with AD is supposed to be caused by apoE-isoform dependent effects on amyloid-beta deposition, no single pathogenetically relevant mechanism has yet been confirmed for MS. In summary we presently may assume only subtle effects of the apoE polymorphism on the course of MS. These effects are probably further modulated by other genes and need further investigation.