APOE gene polymorphisms and susceptibility to Creutzfeldt-Jakob disease

Association between serum apolipoprotein E and cognitive function in Chinese patients with temporal lobe epilepsy

OBJECTIVE

To investigate the effect of serum apolipoprotein E (APOE) levels on cognitive function in patients with temporal lobe epilepsy (TLE).

METHODS

Clinical data were collected from 190 subjects including 110 TLE patients and 80 healthy people. Cognitive function was assessed using the Addenbrooke's Cognitive Examination Revised (ACE-R) scale. Serum levels of APOE were measured using ELISA kits. Genotyping of APOE in peripheral blood was detected by microarray hybridization.

RESULTS

Patients with TLE had significantly lower ACE-R total score, memory and verbal fluency scores compared to the healthy group. Serum levels of APOE were significantly higher in TLE patients than in the healthy subjects. Serum APOE levels were significantly negatively correlated with ACE-R total score, memory and verbal fluency scores. The cognitive function score of TLE with APOE ε4 allele was lower than that of TLE without APOE ε4 allele.

SIGNIFICANCE

Our study showed that serum APOE levels were higher in TLE patients than in the healthy population. And serum APOE levels were associated with cognitive dysfunction in TLE patients. APOE ε4 allele carriers have poor cognitive function in TLE patients.

ApoE gene polymorphisms and metals and their interactions with cognitive function

OBJECTIVE

To analyze the relationship between plasma metal elements, ApoE gene polymorphisms and the interaction between the two and impaired cognitive function in elderly population.

METHOD

A stratified sample was drawn according to the age of the study population, and 911 subjects were included. Baseline information and health indicators were obtained, and cognitive function status was assessed by health examination, a general questionnaire and Mini-Mental Status Examination. Plasma metal elements were measured, and SNP typing was performed. Binary logistic regression was used to analyze the factors influencing cognitive function status and the association between the SNP genetic pattern of the ApoE gene and cognitive function.

RESULTS

The differences in gene frequencies and genotype frequencies of the ApoE rs7412 and rs7259620 genotype frequencies were statistically different between the cognitive impairment group and the control group (P < 0.05). statistically differences were found for the codominant model in rs7412-TT compared with the CC genotype (OR = 3.112 (1.159-8.359), P = 0.024) and rs7259620-AA compared with the GG genotype (OR = 1.588 (1.007-2.504), P = 0.047). Statistically differences were found in the recessive models rs7412-TT compared with (CC + CT) (OR = 2.979 (1.112-7.978), P = 0.030), rs7259620-AA compared with (GG + GA), and rs405509-GG compared with (TT + TG) (OR = 1.548(1.022-2.344), P = 0.039) all of which increased the risk of developing cognitive impairment. The differences in plasma Fe, Cu, and Rb concentrations between the case and control groups were significant (P < 0.05). The regression results showed that the plasma Cd concentrations in the Q1 range was a protective factor for cognitive function compared with Q4 (0.510 (0.291-0.892), P = 0.018). Furthermore, there was a multiplicative interaction between the codominant and recessive models for the Q2 concentrations of Cd and the rs7259620 loci, and the difference was significant, indicating increased risk of developing cognitive impairment (codominant model OR = 3.577 (1.496-8.555), P = 0.004, recessive model OR = 3.505 (1.479-8.307), P = 0.004). There was also a multiplicative interaction between Cd and the recessive model at the rs405509 loci, and the difference was significant, indicating increased risk of developing cognitive impairment (OR = 3.169 (1.400-7.175), P = 0.006).

CONCLUSION

The ApoE rs7412, rs7259620 and rs405509 loci were associated with cognitive impairment in the elderly population, and there was an interaction between plasma metalloid Cd and the rs7259620 and rs405509 loci that increased the risk of cognitive impairment in the elderly population.

Cross interactions between Apolipoprotein E and amyloid proteins in neurodegenerative diseases

Three common Apolipoprotein E isoforms, ApoE2, ApoE3, and ApoE4, are key regulators of lipid homeostasis, among other functions. Apolipoprotein E can interact with amyloid proteins. The isoforms differ by one or two residues at positions 112 and 158, and possess distinct structural conformations and functions, leading to isoform-specific roles in amyloid-based neurodegenerative diseases. Over 30 different amyloid proteins have been found to share similar characteristics of structure and toxicity, suggesting a common interactome. The molecular and genetic interactions of ApoE with amyloid proteins have been extensively studied in neurodegenerative diseases, but have not yet been well connected and clarified. Here we summarize essential features of the interactions between ApoE and different amyloid proteins, identify gaps in the understanding of the interactome and propose the general interaction mechanism between ApoE isoforms and amyloid proteins. Perhaps more importantly, this review outlines what we can learn from the interactome of ApoE and amyloid proteins; that is the need to see both ApoE and amyloid proteins as a basis to understand neurodegenerative diseases.

Sporadic Creutzfeldt-Jakob Disease and Other Proteinopathies in Comorbidity

Background: Sporadic Creutzfeldt–Jakob disease (sCJD) is the most common type of a group of transmissible spongiform encephalopathies (prion diseases). The etiology of the sporadic form of CJD is still unclear. sCJD can occur in combination with other neurodegenerative diseases, which further complicates the diagnosis. Alzheimer's disease (AD), e.g., is often seen in conjunction with sCJD.

Method: In this study, we performed a systematic analysis of 15 genes related to the most important neurodegenerative diseases - AD, frontotemporal dementia, amyotrophic lateral sclerosis, prion disease, and Parkinson's disease - in a cohort of sCJD and sCJD in comorbidity with AD and primary age-related proteinopathy (PART). A total of 30 neuropathologically verified cases of sCJD with and without additional proteinopathies were included in the study. In addition, we compared microtubule-associated protein tau (MAPT) haplotypes between sCJD patients and patients with sCJD and PART or sCJD and AD. Then we studied the interaction between the Apolipoprotein E gene (APOE) and PRNP in sCJD patients.

Results: We did not find any causal mutations in the neurodegenerative disease genes. We did detect a p.E318G missense variant of uncertain significance (VUS) in PSEN1 in three patients. In PRNP, we also found a previously described non-pathogenic insertion (p.P84_Q91Q).

Conclusion: Our pilot study failed to find any critical differences between pure sCJD and sCJD in conjunction with other comorbid neurodegenerative diseases. Further investigations are needed to better understand this phenomenon.

Longitudinal clinical, neuropsychological, and neuroimaging characterization of a kindred with a 12-octapeptide repeat insertion in PRNP: the next generation

BACKGROUND

Highly penetrant inherited mutations in the prion protein gene (PRNP) offer a window to study the pathobiology of prion disorders.

METHOD

Clinical, neuropsychological, and neuroimaging characterization of a kindred.

RESULTS

Three of four mutation carriers have progressed to a frontotemporal dementia phenotype. Declines in neuropsychological function coincided with changes in FDG-PET at the identified onset of cognitive impairment.

CONCLUSIONS AND RELEVANCE

Gene silencing treatments are on the horizon and when they become available, early detection will be crucial. Longitudinal studies involving familial mutation kindreds can offer important insights into the initial neuropsychological and neuroimaging changes necessary for early detection.

The characterization of AD/PART co-pathology in CJD suggests independent pathogenic mechanisms and no cross-seeding between misfolded Aβ and prion proteins

Current evidence indicating a role of the human prion protein (PrP) in amyloid-beta (Aβ) formation or a synergistic effect between Aβ and prion pathology remains controversial. Conflicting results also concern the frequency of the association between the two protein misfolding disorders and the issue of whether the apolipoprotein E gene (APOE) and the prion protein gene (PRNP), the major modifiers of Aβ- and PrP-related pathologies, also have a pathogenic role in other proteinopathies, including tau neurofibrillary degeneration. Here, we thoroughly characterized the Alzheimer's disease/primary age-related tauopathy (AD/PART) spectrum in a series of 450 cases with definite sporadic or genetic Creutzfeldt-Jakob disease (CJD). Moreover, we analyzed: (i) the effect of variables known to affect CJD pathogenesis and the co-occurring Aβ- and tau-related pathologies; (II) the influence of APOE genotype on CJD pathology, and (III) the effect of AD/PART co-pathology on the clinical CJD phenotype. AD/PART characterized 74% of CJD brains, with 53.3% and 8.2% showing low or intermediate-high levels of AD pathology, and 12.4 and 11.8% definite or possible PART. There was no significant correlation between variables affecting CJD (i.e., disease subtype, prion strain, PRNP genotype) and those defining the AD/PART spectrum (i.e., ABC score, Thal phase, prevalence of CAA and Braak stage), and no difference in the distribution of APOE ε4 and ε2 genotypes among CJD subtypes. Moreover, AD/PART co-pathology did not significantly affect the clinical presentation of typical CJD, except for a tendency to increase the frequency of cognitive symptoms. Altogether, the present results seem to exclude an increased prevalence AD/PART co-pathology in sporadic and genetic CJD, and indicate that largely independent pathogenic mechanisms drive AD/PART and CJD pathology even when they coexist in the same brain.

Apolipoprotein E genotypes and longevity across dementia disorders

INTRODUCTION

The ε4 allele of the apolipoprotein E (APOE) gene is a prominent risk factor for Alzheimer's disease (AD), but its implication in other dementias is less well studied.

METHODS

We used a data set on 2858 subjects (1098 AD, 260 vascular dementia [VaD], 145 mixed AD and VaD, 90 other dementia diagnoses, and 1265 controls) to examine the association of APOE polymorphisms with clinical dementia diagnoses, biomarker profiles, and longevity.

RESULTS

The ε4 allele was associated with reduced longevity as ε4 versus ε3 homozygotes lived on average 2.6 years shorter (P = .006). In AD, ε4 carriers lived 1.0 years shorter than noncarriers (P = .028). The ε4 allele was more prevalent in AD, mixed AD and VaD, and VaD patients compared to controls, but not in other dementia disorders.

DISCUSSION

The APOE ε4 allele is influential in AD but might also be of importance in VaD and in mixed AD and VaD, diseases in which concomitant AD pathology is common.

APOE gene and neuropsychiatric disorders and endophenotypes: A comprehensive review

The Apolipoprotein E (APOE) gene is one of the main candidates in neuropsychiatric genetics, with hundreds of studies carried out in order to explore the possible role of polymorphisms in the APOE gene in a large number of neurological diseases, psychiatric disorders, and related endophenotypes. In the current article, we provide a comprehensive review of the structural and functional aspects of the APOE gene and its relationship with brain disorders. Evidence from genome-wide association studies and meta-analyses shows that the APOE gene has been significantly associated with several neurodegenerative disorders. Cellular and animal models show growing evidence of the key role of APOE in mechanisms of brain plasticity and behavior. Future analyses of the APOE gene might find a possible role in other neurological diseases and psychiatric disorders and related endophenotypes. © 2016 Wiley Periodicals, Inc.

Synergism between apolipoprotein E Ɛ4 allele and paraoxonase (PON1) 55-M allele is associated with risk of systemic lupus erythematosus

Evidences indicate that abnormal lipid metabolism and lipid peroxidation can affect the progression of complications in systemic lupus erythematosus (SLE) patients. Apolipoprotein E (ApoE) and paraoxonase-1 (PON1) play important role in lipid metabolism and protection of lipid peroxidation. The polymorphisms of ApoE and paraoxonase (PON1) L55M (Met < Leu) allele genes lead to disorders in lipid metabolism and are related to atherosclerosis. This study is the first investigation to examine the possible association between ApoE and PON1-L55M polymorphisms and correlation with serum arylesterase (ARE) activities of PON, levels of malondialdehyde (MDA), neopterin, and lipid lipoprotein in SLE patients from Iranian western population. The present case-control study consisted of 107 SLE patients and 101 gender- and age-matched, unrelated, healthy controls from Iran's western population. The ApoE and PON1-L55M genotypes were identified using PCR-RFLP method. The serum level of MDA, neopterin, lipid levels, and ARE activity were determined by HPLC, commercial kits, and spectrophotometry, respectively. Our results showed that ApoE ε4 and PON1-55M alleles act synergistically to increase the risk of SLE by 1.47 times (p = 0.038). We found that the frequency of ApoE Ɛ3/Ɛ4 genotype was higher in SLE patients (11.2%) compared with control subjects (5%), although the difference was not significant (p = 0.087). This study for the first time not only demonstrates that ApoE Ɛ4 and PON-55M alleles synergistically increase the risk of SLE but also reveals that serum levels of MDA, neopterin, and LDL-C are high in SLE patients. This information may be in value for evaluating SLE progression and in the elucidation of the mechanisms of the disease pathogenesis.

Role of apolipoprotein E polymorphism as a prognostic marker in traumatic brain injury and neurodegenerative disease: a critical review

OBJECT

The difference in course and outcome of several neurodegenerative conditions and traumatic injuries of the nervous system points toward a possible role of genetic and environmental factors as prognostic markers. Apolipoprotein E (Apo-E), a key player in lipid metabolism, is recognized as one of the most powerful genetic risk factors for dementia and other neurodegenerative diseases. In this article, the current understanding of APOE polymorphism in various neurological disorders is discussed.

METHODS

The English literature was searched for various studies describing the role of APOE polymorphism as a prognostic marker in neurodegenerative diseases and traumatic brain injury. The wide ethnic distribution of APOE polymorphism was discussed, and the recent meta-analyses of role of APOE polymorphism in multiple diseases were analyzed and summarized in tabular form.

RESULTS

Results from the review of literature revealed that the distribution of APOE is varied in different ethnic populations. APOE polymorphism plays a significant role in pathogenesis of neurodegeneration, particularly in Alzheimer’s disease. APOE ε4 is considered a marker for poor prognosis in various diseases, but APOE ε2 rather than APOE ε4 has been associated with cerebral amyloid angiopathy-related bleeding and sporadic Parkinson’s disease. The role of APOE polymorphism in various neurological diseases has not been conclusively elucidated.

CONCLUSIONS

Apo-E is a biomarker for various neurological and systemic diseases. Therefore, while analyzing the role of APOE polymorphism in neurological diseases, the interpretation should be done after adjusting all the confounding factors. A continuous quest to look for associations with various neurological diseases and wide knowledge of available literature are required to improve the understanding of the role of APOE polymorphism in these conditions and identify potential therapeutic targets.

The potential applications of Apolipoprotein E in personalized medicine

Personalized medicine uses various individual characteristics to guide medical decisions. Apolipoprotein (ApoE), the most studied polymorphism in humans, has been associated with several diseases. The purpose of this review is to elucidate the potential role of ApoE polymorphisms in personalized medicine, with a specific focus on neurodegenerative diseases, by giving an overview of its influence on disease risk assessment, diagnosis, prognosis, and therapy. This review is not a systematic inventory of the literature, but rather a summary and discussion of novel, influential and promising works in the field of ApoE research that could be valuable for personalized medicine. Empirical evidence suggests that ApoE genotype informs pre-symptomatic risk for a wide variety of diseases, is valuable for the diagnosis of type III dysbetalipoproteinemia, increases risk of dementia in neurodegenerative diseases, and is associated with a poor prognosis following acute brain damage. ApoE status appears to influence the efficacy of certain drugs, outcome of clinical trials, and might also give insight into disease prevention. Assessing ApoE genotype might therefore help to guide medical decisions in clinical practice.