%0 Journal Article %J J Alzheimers Dis %D 2018 %T Assessment of the Genetic Architecture of Alzheimer's Disease Risk in Rate of Memory Decline. %A Del-Aguila, Jorge L %A Fernández, Maria Victoria %A Schindler, Suzanne %A Ibanez, Laura %A Deming, Yuetiva %A Ma, Shengmei %A Saef, Ben %A Black, Kathleen %A Budde, John %A Norton, Joanne %A Chasse, Rachel %A Harari, Oscar %A Goate, Alison %A Xiong, Chengjie %A Morris, John C %A Cruchaga, Carlos %K Age of Onset %K Aged %K Aged, 80 and over %K Alzheimer Disease %K Dementia %K Disease Progression %K Female %K Genetic Predisposition to Disease %K Genome-Wide Association Study %K Heterozygote %K Humans %K Longitudinal Studies %K Male %K Membrane Glycoproteins %K Memory Disorders %K Middle Aged %K Polymorphism, Single Nucleotide %K Receptors, Immunologic %K Risk Assessment %X

Many genetic studies for Alzheimer's disease (AD) have been focused on the identification of common genetic variants associated with AD risk and not on other aspects of the disease, such as age at onset or rate of dementia progression. There are multiple approaches to untangling the genetic architecture of these phenotypes. We hypothesized that the genetic architecture of rate of progression is different than the risk for developing AD dementia. To test this hypothesis, we used longitudinal clinical data from ADNI and the Knight-ADRC at Washington University, and we calculated PRS (polygenic risk score) based on the IGAP study to compare the genetic architecture of AD risk and dementia progression. Dementia progression was measured by the change of Clinical Dementia Rating Sum of Boxes (CDR)-SB per year. Out of the 21 loci for AD risk, no association with the rate of dementia progression was found. The PRS rate was significantly associated with the rate of dementia progression (β= 0.146, p = 0.03). In the case of rare variants, TREM2 (β= 0.309, p = 0.02) was also associated with the rate of dementia progression. TREM2 variant carriers showed a 23% faster rate of dementia compared with non-variant carriers. In conclusion, our results indicate that the recently identified common and rare variants for AD susceptibility have a limited impact on the rate of dementia progression in AD patients.

%B J Alzheimers Dis %V 62 %P 745-756 %8 2018 %G eng %N 2 %1 http://www.ncbi.nlm.nih.gov/pubmed/29480181?dopt=Abstract %R 10.3233/JAD-170834 %0 Journal Article %J N Engl J Med %D 2013 %T TREM2 variants in Alzheimer's disease. %A Guerreiro, Rita %A Wojtas, Aleksandra %A Bras, Jose %A Carrasquillo, Minerva %A Rogaeva, Ekaterina %A Majounie, Elisa %A Cruchaga, Carlos %A Sassi, Celeste %A Kauwe, John S K %A Younkin, Steven %A Hazrati, Lilinaz %A Collinge, John %A Pocock, Jennifer %A Lashley, Tammaryn %A Williams, Julie %A Lambert, Jean-Charles %A Amouyel, Philippe %A Goate, Alison %A Rademakers, Rosa %A Morgan, Kevin %A Powell, John %A St George-Hyslop, Peter %A Singleton, Andrew %A Hardy, John %K Aged %K Alzheimer Disease %K Animals %K Brain %K Exome %K Genetic Variation %K Genome-Wide Association Study %K Genotype %K Genotyping Techniques %K Heterozygote %K Humans %K Membrane Glycoproteins %K Mice %K Mice, Inbred A %K Mutation %K Receptors, Immunologic %K Risk Factors %K RNA, Messenger %K Sequence Analysis, DNA %X

BACKGROUND: Homozygous loss-of-function mutations in TREM2, encoding the triggering receptor expressed on myeloid cells 2 protein, have previously been associated with an autosomal recessive form of early-onset dementia.

METHODS: We used genome, exome, and Sanger sequencing to analyze the genetic variability in TREM2 in a series of 1092 patients with Alzheimer's disease and 1107 controls (the discovery set). We then performed a meta-analysis on imputed data for the TREM2 variant rs75932628 (predicted to cause a R47H substitution) from three genomewide association studies of Alzheimer's disease and tested for the association of the variant with disease. We genotyped the R47H variant in an additional 1887 cases and 4061 controls. We then assayed the expression of TREM2 across different regions of the human brain and identified genes that are differentially expressed in a mouse model of Alzheimer's disease and in control mice.

RESULTS: We found significantly more variants in exon 2 of TREM2 in patients with Alzheimer's disease than in controls in the discovery set (P=0.02). There were 22 variant alleles in 1092 patients with Alzheimer's disease and 5 variant alleles in 1107 controls (P<0.001). The most commonly associated variant, rs75932628 (encoding R47H), showed highly significant association with Alzheimer's disease (P<0.001). Meta-analysis of rs75932628 genotypes imputed from genomewide association studies confirmed this association (P=0.002), as did direct genotyping of an additional series of 1887 patients with Alzheimer's disease and 4061 controls (P<0.001). Trem2 expression differed between control mice and a mouse model of Alzheimer's disease.

CONCLUSIONS: Heterozygous rare variants in TREM2 are associated with a significant increase in the risk of Alzheimer's disease. (Funded by Alzheimer's Research UK and others.).

%B N Engl J Med %V 368 %P 117-27 %8 2013 Jan 10 %G eng %N 2 %1 http://www.ncbi.nlm.nih.gov/pubmed/23150934?dopt=Abstract %R 10.1056/NEJMoa1211851 %0 Journal Article %J Sci Transl Med %D 2011 %T Human apoE isoforms differentially regulate brain amyloid-β peptide clearance. %A Castellano, Joseph M %A Kim, Jungsu %A Stewart, Floy R %A Jiang, Hong %A DeMattos, Ronald B %A Patterson, Bruce W %A Fagan, Anne M %A Morris, John C %A Mawuenyega, Kwasi G %A Cruchaga, Carlos %A Goate, Alison M %A Bales, Kelly R %A Paul, Steven M %A Bateman, Randall J %A Holtzman, David M %K Adult %K Aged %K Alleles %K Alzheimer Disease %K Amyloid beta-Peptides %K Animals %K Apolipoprotein E4 %K Biomarkers %K Brain %K Female %K Genotype %K Humans %K Male %K Mice %K Mice, Inbred C57BL %K Mice, Transgenic %K Microdialysis %K Middle Aged %K Protein Isoforms %X

The apolipoprotein E (APOE) ε4 allele is the strongest genetic risk factor for late-onset, sporadic Alzheimer's disease (AD). The APOE ε4 allele markedly increases AD risk and decreases age of onset, likely through its strong effect on the accumulation of amyloid-β (Aβ) peptide. In contrast, the APOE ε2 allele appears to decrease AD risk. Most rare, early-onset forms of familial AD are caused by autosomal dominant mutations that often lead to overproduction of Aβ(42) peptide. However, the mechanism by which APOE alleles differentially modulate Aβ accumulation in sporadic, late-onset AD is less clear. In a cohort of cognitively normal individuals, we report that reliable molecular and neuroimaging biomarkers of cerebral Aβ deposition vary in an apoE isoform-dependent manner. We hypothesized that human apoE isoforms differentially affect Aβ clearance or synthesis in vivo, resulting in an apoE isoform-dependent pattern of Aβ accumulation later in life. Performing in vivo microdialysis in a mouse model of Aβ-amyloidosis expressing human apoE isoforms (PDAPP/TRE), we find that the concentration and clearance of soluble Aβ in the brain interstitial fluid depends on the isoform of apoE expressed. This pattern parallels the extent of Aβ deposition observed in aged PDAPP/TRE mice. ApoE isoform-dependent differences in soluble Aβ metabolism are observed not only in aged but also in young PDAPP/TRE mice well before the onset of Aβ deposition in amyloid plaques in the brain. Additionally, amyloidogenic processing of amyloid precursor protein and Aβ synthesis, as assessed by in vivo stable isotopic labeling kinetics, do not vary according to apoE isoform in young PDAPP/TRE mice. Our results suggest that APOE alleles contribute to AD risk by differentially regulating clearance of Aβ from the brain, suggesting that Aβ clearance pathways may be useful therapeutic targets for AD prevention.

%B Sci Transl Med %V 3 %P 89ra57 %8 2011 Jun 29 %G eng %N 89 %1 http://www.ncbi.nlm.nih.gov/pubmed/21715678?dopt=Abstract %R 10.1126/scitranslmed.3002156 %0 Journal Article %J PLoS One %D 2010 %T Genetic evidence implicates the immune system and cholesterol metabolism in the aetiology of Alzheimer's disease. %A Jones, Lesley %A Holmans, Peter A %A Hamshere, Marian L %A Harold, Denise %A Moskvina, Valentina %A Ivanov, Dobril %A Pocklington, Andrew %A Abraham, Richard %A Hollingworth, Paul %A Sims, Rebecca %A Gerrish, Amy %A Pahwa, Jaspreet Singh %A Jones, Nicola %A Stretton, Alexandra %A Morgan, Angharad R %A Lovestone, Simon %A Powell, John %A Proitsi, Petroula %A Lupton, Michelle K %A Brayne, Carol %A Rubinsztein, David C %A Gill, Michael %A Lawlor, Brian %A Lynch, Aoibhinn %A Morgan, Kevin %A Brown, Kristelle S %A Passmore, Peter A %A Craig, David %A McGuinness, Bernadette %A Todd, Stephen %A Holmes, Clive %A Mann, David %A Smith, A David %A Love, Seth %A Kehoe, Patrick G %A Mead, Simon %A Fox, Nick %A Rossor, Martin %A Collinge, John %A Maier, Wolfgang %A Jessen, Frank %A Schürmann, Britta %A Heun, Reinhard %A Kölsch, Heike %A van den Bussche, Hendrik %A Heuser, Isabella %A Peters, Oliver %A Kornhuber, Johannes %A Wiltfang, Jens %A Dichgans, Martin %A Frölich, Lutz %A Hampel, Harald %A Hüll, Michael %A Rujescu, Dan %A Goate, Alison M %A Kauwe, John S K %A Cruchaga, Carlos %A Nowotny, Petra %A Morris, John C %A Mayo, Kevin %A Livingston, Gill %A Bass, Nicholas J %A Gurling, Hugh %A McQuillin, Andrew %A Gwilliam, Rhian %A Deloukas, Panos %A Al-Chalabi, Ammar %A Shaw, Christopher E %A Singleton, Andrew B %A Guerreiro, Rita %A Mühleisen, Thomas W %A Nöthen, Markus M %A Moebus, Susanne %A Jöckel, Karl-Heinz %A Klopp, Norman %A Wichmann, H-Erich %A Rüther, Eckhard %A Carrasquillo, Minerva M %A Pankratz, V Shane %A Younkin, Steven G %A Hardy, John %A O'Donovan, Michael C %A Owen, Michael J %A Williams, Julie %K Alzheimer Disease %K Apolipoproteins E %K Cholesterol %K Chromosome Mapping %K Genetic Predisposition to Disease %K Genome, Human %K Genome-Wide Association Study %K Humans %K Immune System %K Polymorphism, Single Nucleotide %X

BACKGROUND: Late Onset Alzheimer's disease (LOAD) is the leading cause of dementia. Recent large genome-wide association studies (GWAS) identified the first strongly supported LOAD susceptibility genes since the discovery of the involvement of APOE in the early 1990s. We have now exploited these GWAS datasets to uncover key LOAD pathophysiological processes.

METHODOLOGY: We applied a recently developed tool for mining GWAS data for biologically meaningful information to a LOAD GWAS dataset. The principal findings were then tested in an independent GWAS dataset.

PRINCIPAL FINDINGS: We found a significant overrepresentation of association signals in pathways related to cholesterol metabolism and the immune response in both of the two largest genome-wide association studies for LOAD.

SIGNIFICANCE: Processes related to cholesterol metabolism and the innate immune response have previously been implicated by pathological and epidemiological studies of Alzheimer's disease, but it has been unclear whether those findings reflected primary aetiological events or consequences of the disease process. Our independent evidence from two large studies now demonstrates that these processes are aetiologically relevant, and suggests that they may be suitable targets for novel and existing therapeutic approaches.

%B PLoS One %V 5 %P e13950 %8 2010 %G eng %N 11 %1 http://www.ncbi.nlm.nih.gov/pubmed/21085570?dopt=Abstract %R 10.1371/journal.pone.0013950