Association of apolipoprotein E polymorphism to clinical heterogeneity of multiple sclerosis

Association of APOE Serum Levels and APOE ε2, ε3, and ε4 Alleles with Optic Neuritis

Optical neuritis (ON), otherwise known as optical nerve damage, is a term used to describe various environmental and body conditions that lead to optic nerve dysfunction. Neurologists are well aware of conditions that cause optic neuropathy, such as trauma, infections, malnutrition, and various toxins. As optic neuritis is a multifactorial demyelinating or infectious process, genetic predisposition may also influence the progression of optic neuritis. This study aimed to evaluate the association of ON (with and without multiple sclerosis) with APOE alleles and APOE serum levels. We found that the APOE ε3/ε3 genotype was statistically less common in the ON group of males than in the control group (p = 0.045). Moreover, the APOE ε3/ε3 genotype had a 3.7-fold increase in the odds of ON development in males (OR = 3.698; CI: 1.503–9.095; p = 0.004). In contrast, the APOE ε3/ε4 genotype had a 4.1-fold decrease in the odds of ON development in males (OR = 0.242; CI: 0.083–0.704; p = 0.009). APOE serum levels were statistically significantly higher in the ON group than in the control group (p = 0.042). The APOE ε3/ε3 genotype may increase males’ risk of developing ON, while the ε3/ε4 genotype may reduce males’ risk of developing ON.

Association of apolipoprotein E and myeloperoxidase genotypes to clinical course of familial and sporadic multiple sclerosis

The importance of apolipoprotein E (ApoE) and myeloperoxidase (MPO) genotypes in the clinical characteristics of multiple sclerosis (MS) has been recently emphasized. In a large group of Polish patients we have tested the hypothesis that polymorphism in ApoE and MPO genes may influence the course of the disease. G enotypes were determined in 117 MS patients (74 females and 43 males; 99 sporadic and 18 familial cases) with mean EDSS of 3.6, mean age of 44.1 years, mean duration of the disease 12.8 years and mean onset of MS at 31.2 years, and in 100 healthy controls. The relationship between ApoE and MPO genes’ polymorphism and the MS activity as well as the defect of remyelination (diffuse demyelination) and brain atrophy on MRI were analysed. The ApoE o4 allele was not related to the disease course or the ApoE o2 to the intensity of demyelination on MRI. The genotype MPO G/G was found in all familial MS and in 57% (56/99) of sporadic cases. This genotype was also related to more pronounced brain atrophy on MRI. The MPO G/G subpopulation was characterized by a significantly higher proportion of patients with secondary progressive MS (PB- 0.05) and by a higher value of EDSS. A ccording to our results the MPO G allele is frequently found (in 96% of cases) among Polish patients with MS. More severe nervous tissue damage in the MPO G/G form can be explained by the mechanism of accelerated oxidative stress. It seems that MPO G/G genotype may be one of the genetic factors influencing the progression rate of disability in MS patients.

Cognitive impairment in patients with multiple sclerosis: association with the APOE gene and promoter polymorphisms

Background Studies examining the ε4 allele of the APOE gene as a factor affecting the severity of multiple sclerosis (MS) have yielded conflicting results. The focus of these studies on physical disability to the neglect of cognitive impairment is surprising in light of the associations between the ε4 allele and other dementia conditions. Only two studies examine the relationship between the ε4 allele and cognitive impairment.

Methods A neuropsychological test battery was administered to 263 MS patients, and their current disability status was evaluated. Genotypes were determined for APOE epsilon and for two promoter region polymorphisms (-219 G/T and -491 A/T).

Results Although effects were generally weak, female patients with the -491 AA genotype had a later age of disease onset, lower disability scores, and somewhat higher scores on the cognitive battery. Male patients with the ε2 allele had lower disability and higher scores on the cognitive battery. The ε4 allele was not related to physical disability, and there was no difference between ε4+and ε4– patients in overall cognitive performance. However, when patients with severe cognitive impairment were identified, a greater proportion (52%) of these patients had the ε4 allele than those in the unimpaired group (27%).

Conclusion An association with the ε4 allele was evident in this study, but only in cases of severe cognitive impairment.

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.

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).

ApoE alleles, depression and positive affect in multiple sclerosis

BACKGROUND

The role of apolipoprotein E (ApoE) alleles has received recent attention in depressive disorders, the ApoE epsilon4 conferring greater risk for poorer outcomes, and the ApoE epsilon2 allele providing some protective effects. Depression is common in multiple sclerosis (MS) and the role of ApoE alleles is unknown.

AIMS

To evaluate ApoE alleles in relation to symptoms of depression in a cohort of patients with MS participating in the Sonya Slifka Longitudinal Multiple Sclerosis Study (Slifka Study). To examine risk and protection, depressed mood and positive affect were each investigated with respect to the ApoE epsilon4 and ApoE epsilon2 alleles, respectively.

RESULTS

Of the total 101 participants, 22.8% were ApoE epsilon2 carriers and 21.8% were ApoE epsilon4 carriers. Hierarchical linear regression analyses suggested that after controlling for demographics, disease duration, and disability, ApoE epsilon2 significantly predicted increased positive affect (R2Delta=0.05, F(1,94)=5.44, P=0.02) and was associated with decreased severity of depressive symptoms, although this did not reach statistical significance (R2Delta=0.03, F(1,94)=3.44, P=0.06). ApoE epsilon4 did not significantly predict depression status.

CONCLUSION

The presence of the ApoE epsilon2 allele in this study is suggested to be protective against depressive symptoms in our subsample of patients recruited from the Slifka Study. These findings are consistent with reports in psychiatric populations linking ApoE epsilon2 with decreased incidence of depressive disorders. Further investigation would be warranted to understand the role of ApoE genotypes and risk for depressive symptoms.

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.

Differential course of HIV-1 infection and apolipoprotein E polymorphism

We studied the course of infection with human immunodeficiency virus type 1 (HIV-1) in relation to apolipoprotein E (APOE) polymorphism found for 209 Italians treated at Infectious Disease Clinics in Rome and Modena. Clinically, patients were classified into four groups according to the yearly rate of decline in CD4+ cell count (LTNP: long-term non-progression; SLOW, ’NORMAL’ or RAPID). Patients at both extremes of the clinical spectrum, i.e. those who rapidly progressed to AIDS and those with stable high CD4 cell counts, had few APOE ɛ4 and ɛ2 alleles (P = 0.04). Detailed clinical information was then used to construct four model-based clinical profiles using grade-of-membership analysis (GoM), predictive of APOE genotypic frequencies: 1. The clinical profile associated with good long-term prognosis lacked ɛ2 (P=0.01); 2. Disease progression to AIDS was associated with ɛ4 and ɛ2, most evident for zidovudine-lamivudine regimens without a protease inhibitor (P = 0.03); and, 3. AIDS patients had low ɛ4 and ɛ2 frequencies, consistent with a high mortality rate among ɛ4+ and ɛ2+ AIDS patients. These findings suggest allele-specific immunomodulatory effects involving inherited APOE isoform important enough to alter the clinical course of HIV infection and, possibly, drug efficacy. They imply a connection between lipid metabolism and immunity potentially relevant to common disorders.

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.

Multiple sclerosis genetics: leaving no stone unturned

Compelling epidemiologic and molecular data indicate that genes play a primary role in determining who is at risk for developing multiple sclerosis (MS), how the disease progresses, and how someone responds to therapy. The genetic component of MS etiology is believed to result from the action of allelic variants in several genes. Their incomplete penetrance and moderate individual effect probably reflects epistatic interactions, post-transcriptional regulatory mechanisms, and significant environmental influences. Equally significant, it is also likely that locus heterogeneity exists, whereby specific genes influence susceptibility and pathogenesis in some individuals but not in others. With the aid of novel analytical algorithms, the combined study of genomic, transcriptional, proteomic, and phenotypic information in well-controlled study groups will define a useful conceptual model of pathogenesis and a framework for understanding the mechanisms of action of existing therapies for this disorder, as well as the rationale for novel curative strategies.

Apo E in multiple sclerosis and optic neuritis: the apo E-epsilon4 allele is associated with progression of multiple sclerosis

OBJECTIVE

To investigate the association between apolipoprotein E (Apo E) genotype in multiple sclerosis (MS) and acute monosymptomatic optic neuritis (ON) in a genetically homogeneous population with a high frequency of the Apo epsilon4 allele.

BACKGROUND

The association between heterozygosity of Apo epsilon4 and the development of MS is thoroughly investigated, while the association between homozygosity of Apo epsilon4 and the development of MS is insufficiently studied. The association between Apo E genotype and disease progression remains controversial.

METHODS

475 patients were included, 385 with MS and 90 with ON, consecutively seen in the MS clinic in the County of Copenhagen. Clinical data were obtained from medical records and degree of disability was determined prospectively using the Kurtzke expanded disability status scale (EDSS). Blood samples were used for Apo E genotyping. Disease progression was evaluated by the progression index (PI = EDSS/disease duration). Apo E genotype distribution was compared with 361 healthy controls.

RESULTS

The Apo epsilon genotype distribution in the MS and ON groups was similar to the controls. The rate of disease progression in the group of MS patients with a disease duration of 10 years or less was significantly faster in the Apo epsilon4 positive group (heterozygosity and homozygosity for Apo epsilon4) (PI = 1.41) compared to the Apo epsilon4 negative group (PI =0.92) (P =0.009). Observing the MS subgroups, we found that the group of patients with RRMS had a faster rate of disease progression in the Apo epsilon4 positive group (PI =1.12) compared to the Apo epsilon4 negative group (P =0.77) (P =0.024).

CONCLUSIONS

Apo E genotypes do not influence the development of MS and ON. The Apo epsilon4 allele seems to predispose carriers with MS to a faster progression of disease.

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

BACKGROUND

The possible pathogenetic relationship between APOE genetic polymorphism and susceptibility to a variety of neurodegenerative disorders, including multiple sclerosis, is controversial. Previous studies have been conducted in Caucasian subjects, with little or no data on subjects from the Arabian Gulf. We compared the frequencies of specific APOE genotypes and alleles in patients with multiple sclerosis (MS) with frequencies observed in a healthy control Kuwaiti Arab population to relate APOE frequencies with specific identifiable clinical features of the disease.

METHODS

Two groups of subjects were studied: (i) 39 (17 M, 22 F) patients with clinical evidence of MS; (ii) 106 apparently healthy Kuwaitis recruited as control subjects. The MS patients had detailed clinical and laboratory evaluations, and APOE genotypes were determined in all the subjects (patients and controls) by validated PCR methods. Differences in frequencies of APOE alleles and associations of specific alleles with clinical features were assessed.

RESULTS

There were no significant differences in allele frequencies between patients and controls, although there was a statistically insignificant trend towards lower APOE2 allele frequency in the patients (p=0.09). There was a significant association of the APOE4 allele with female gender in the patients (p<0.05).

CONCLUSION

In Kuwaitis, a population with low MS prevalence, no statistically significant associations between APOE genetic polymorphism and susceptibility to MS could be established, but there was a trend towards a lower APOE2 frequency with MS and towards increased frequency of APOE4 in female patients and with severe disease.

Biological markers in CSF and blood for axonal degeneration in multiple sclerosis

Biomarkers in body fluids could help to predict and monitor neurological decline in people with multiple sclerosis (MS). We discuss markers for axonal damage in body fluids in people with MS. The most promising axonal marker for discriminating patients with MS from those with other neurological diseases is the neurofilament light chain in CSF. Antibodies against the heavy-chain isoform are associated with disease progression. Other studies have shown altered CSF concentrations of tau proteins, actin, tubulin, and 14-3-3 protein. Interestingly, the concentration of 24S-hydroxycholesterol was decreased in serum of patients with MS. No clear changes have been shown for the markers apolipoprotein E and neurospecific enolase. We describe three types of markers for axonal damage: markers that reflect processes in the CNS, those that reflect extraneural processes, and those that reflect whole-body changes. These concepts may be helpful for biomarker research in various neurodegenerative diseases.

No major association of ApoE genotype with disease characteristics and MRI findings in multiple sclerosis

BACKGROUND

Whereas a number of studies suggest that the ApoE polymorphism is not associated with disease susceptibility in multiple sclerosis (MS), results with regard to disease severity, however, are conflicting. Some studies suggest an unfavourable role of the epsilon4 allele. This study was performed to assess the association of the ApoE polymorphism with both disease susceptibility and disease course in a large group of MS patients using clinical and MRI measures. In addition the data were combined with available data from the literature.

METHODS

In a group of 408 patients with clinically definite MS, genotype distribution was compared with that of 144 healthy controls. Combined analysis of published data on the association of ApoE polymorphism with MS was performed. Demographic and clinical findings were recorded and related to the ApoE genotype. In a subgroup, longitudinal MRI findings were available and related to the ApoE genotype.

RESULTS

No significant differences were found in the distribution of genotypes between MS patients and controls. Combined analysis of published data showed a slightly increased susceptibility for MS in epsilon2-carriers. Disease characteristics (including age at onset and onset type), disease severity (progression index, time to reach EDSS 6) and MRI findings (lesion volumes and atrophy measures) were not associated with carriership o epsilon2 or epsilon4.

CONCLUSIONS

In this cohort no association of the ApoE genotype with disease susceptibility nor clinical and MRI measures could be identified. However, combined analysis of published data could not definitely exclude the possibility of a minor role for epsilon2-carriership in MS.

Polymorphisms of apolipoprotein E and Japanese patients with multiple sclerosis

The relation between apolipoprotein (APOE) gene polymorphisms and disease progression of multiple sclerosis (MS) is controversial. The present study was designed to investigate the relation between APOE gene polymorphisms and Japanese patients with MS. We analysed the frequencies of APOE gene polymorphisms in 135 MS patients and 134 healthy controls, using PCR-RFLP. The results showed no significant differences in the distribution of APOE gene polymorphisms between MS patients and controls. With regard to disease progression, there was no association between APOE gene polymorphisms and epsilon4 allele positivity and disease progression index (EDSS/ years). Furthermore, in patients with more than 10 years of disease onset, there were no significant differences between the frequencies of epsilon4 allele and patients with EDSS of more than 6. Although the low rate of epsilon4 allele in Japan should be taken into consideration, our results showed no relation between APOE gene polymorphisms and Japanese patients with MS.

Genetics of multiple sclerosis: linkage and association studies

Multiple sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system caused by an interplay of environmental and genetic factors. The only genetic region that has been clearly demonstrated by linkage and association studies to contribute to MS genetic susceptibility is the human leukocyte antigen (HLA) system. The majority of HLA population studies in MS have focused on Caucasians of Northern European descent, where the predisposition to disease has been consistently associated with the class II DRB1*1501-DQA1*0102-DQB1*0602 haplotype. A positive association with DR4 was detected in Sardinians and in other Mediterranean populations. Moreover DR1, DR7, DR11 have been found to be protective in several populations. Systematic searches aimed at identifying non-HLA susceptibility genes were undertaken in several populations by means of linkage studies with microsatellite markers distributed across the whole genome. The conclusion of these studies was that there is no major MS locus, and genetic susceptibility to the disease is most likely explained by the presence of different genes each conferring a small contribution to the overall familial aggregation. The involvement of several candidate genes was tested by association studies, utilizing either a population-based (case control) or a family-based (transmission disequilibrium test) approach. Candidate genes were selected mainly on the basis of their involvement in the autoimmune pathogenesis and include immunorelevant molecules such as cytokines, cytokine receptors, immunoglobulin, T cell receptor subunits and myelin antigens. With the notable exception of HLA, association studies met only modest success. This failure may result from the small size of the tested samples and the small number of markers considered for each gene. New tools for large scale screening are needed to identify genetic determinants with a low phenotypic effect. Large collaborative studies are planned to screen several thousands of patients with MS with several thousands of genetic markers. The tests are increasingly based on the DNA pooling procedure.

APOE genotypes and disease severity in multiple sclerosis

Apolipoprotein E (opoE) is involved in the transport of lipids necessary for membrane repair and is encoded by a gene on chromosome 19q13, a region positive for linkage in two multiple sclerosis (MS) genome-wide screens. The APOE epsilon4 allele confers susceptibility to both familial and sporadic Alzheimer's disease (AD). Carriage of epsilon4 is associated with defective dendritic remodeling in AD, and with unfavorable clinical outcome in head trauma and cerebrovascular disease. According to the results of previous studies, APOE epsilon4 does not increase the risk of developing MS, but it may influence disease progression and ultimate disability. From a total cohort of over 900 MS patients, we compared APOE epsilon2-4 genotypes in, roughly, the cohort's least disabled and most disabled septiles. 'Benign MS' (n=124) was defined as an Expanded Disability Status Scale (EDSS) score of 3.0 or less, despite at least 10 years of disease duration, and 'severe MS' (n=140) as the attainment of an EDSS score of 6.0 within 8 years of disease onset. We found no significant differences in genotype or phenotype frequencies between the benign-MS and severe-MS septiles; however, the risk conferred by epsilon4 rose progressively upon comparison of carriage rates in more narrowly defined anti-podal quantiles.

Association of polymorphisms in the apolipoprotein E region with susceptibility to and progression of multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system, with a complex etiology that includes a strong genetic component. The contribution of the major histocompatibility complex (MHC) has been established in numerous genetic linkage and association studies. In addition to the MHC, the chromosome 19q13 region surrounding the apolipoprotein E (APOE) gene has shown consistent evidence of involvement in MS when family-based analyses were conducted. Furthermore, several clinical reports have suggested that the APOE-4 allele may be associated with more-severe disease and faster progression of disability. To thoroughly examine the role of APOE in MS, we genotyped its functional alleles, as well as seven single-nucleotide polymorphisms (SNPs) located primarily within 13 kb of APOE, in a data set of 398 families. Using family-based association analysis, we found statistically significant evidence that an SNP haplotype near APOE is associated with MS susceptibility (P=.005). An analysis of disease progression in 614 patients with MS from 379 families indicated that APOE-4 carriers are more likely to be affected with severe disease (P=.03), whereas a higher proportion of APOE-2 carriers exhibit a mild disease course (P=.02).