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- de Rojas, I., et al.
(författare)
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Common variants in Alzheimer’s disease and risk stratification by polygenic risk scores
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Genetic discoveries of Alzheimer’s disease are the drivers of our understanding, and together with polygenetic risk stratification can contribute towards planning of feasible and efficient preventive and curative clinical trials. We first perform a large genetic association study by merging all available case-control datasets and by-proxy study results (discovery n = 409,435 and validation size n = 58,190). Here, we add six variants associated with Alzheimer’s disease risk (near APP, CHRNE, PRKD3/NDUFAF7, PLCG2 and two exonic variants in the SHARPIN gene). Assessment of the polygenic risk score and stratifying by APOE reveal a 4 to 5.5 years difference in median age at onset of Alzheimer’s disease patients in APOE ɛ4 carriers. Because of this study, the underlying mechanisms of APP can be studied to refine the amyloid cascade and the polygenic risk score provides a tool to select individuals at high risk of Alzheimer’s disease. © 2021, The Author(s).
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| 5. |
- Bonham, LW, et al.
(författare)
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Genetic variation across RNA metabolism and cell death gene networks is implicated in the semantic variant of primary progressive aphasia
- 2019
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1, s. 10854-
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Tidskriftsartikel (refereegranskat)abstract
- The semantic variant of primary progressive aphasia (svPPA) is a clinical syndrome characterized by neurodegeneration and progressive loss of semantic knowledge. Unlike many other forms of frontotemporal lobar degeneration (FTLD), svPPA has a highly consistent underlying pathology composed of TDP-43 (a regulator of RNA and DNA transcription metabolism). Previous genetic studies of svPPA are limited by small sample sizes and a paucity of common risk variants. Despite this, svPPA’s relatively homogenous clinicopathologic phenotype makes it an ideal investigative model to examine genetic processes that may drive neurodegenerative disease. In this study, we used GWAS metadata, tissue samples from pathologically confirmed frontotemporal lobar degeneration, and in silico techniques to identify and characterize protein interaction networks associated with svPPA risk. We identified 64 svPPA risk genes that interact at the protein level. The protein pathways represented in this svPPA gene network are critical regulators of RNA metabolism and cell death, such as SMAD proteins and NOTCH1. Many of the genes in this network are involved in TDP-43 metabolism. Contrary to the conventional notion that svPPA is a clinical syndrome with few genetic risk factors, our analyses show that svPPA risk is complex and polygenic in nature. Risk for svPPA is likely driven by multiple common variants in genes interacting with TDP-43, along with cell death,x` working in combination to promote neurodegeneration.
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| 6. |
- Dumurgier, J., et al.
(författare)
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A Pragmatic, Data-Driven Method to Determine Cutoffs for CSF Biomarkers of Alzheimer Disease Based on Validation Against PET Imaging
- 2022
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 0028-3878 .- 1526-632X. ; 99:7, s. E669-E678
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Tidskriftsartikel (refereegranskat)abstract
- Background and Objectives To elaborate a new algorithm to establish a standardized method to define cutoffs for CSF biomarkers of Alzheimer disease (AD) by validating the algorithm against CSF classification derived from PET imaging. Methods Low and high levels of CSF phosphorylated tau were first identified to establish optimal cutoffs for CSF beta-amyloid (A beta) peptide biomarkers. These A beta cutoffs were then used to determine cutoffs for CSF tau and phosphorylated tau markers. We compared this algorithm to a reference method, based on tau and amyloid PET imaging status (ADNI study), and then applied the algorithm to 10 large clinical cohorts of patients. Results A total of 6,922 patients with CSF biomarker data were included (mean [SD] age: 70.6 [8.5] years, 51.0% women). In the ADNI study population (n = 497), the agreement between classification based on our algorithm and the one based on amyloid/tau PET imaging was high, with Cohen's kappa coefficient between 0.87 and 0.99. Applying the algorithm to 10 large cohorts of patients (n = 6,425), the proportion of persons with AD ranged from 25.9% to 43.5%. Discussion The proposed novel, pragmatic method to determine CSF biomarker cutoffs for AD does not require assessment of other biomarkers or assumptions concerning the clinical diagnosis of patients. Use of this standardized algorithm is likely to reduce heterogeneity in AD classification.
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| 8. |
- Gao, YX, et al.
(författare)
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Mendelian randomization implies no direct causal association between leukocyte telomere length and amyotrophic lateral sclerosis
- 2020
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1, s. 12184-
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Tidskriftsartikel (refereegranskat)abstract
- We employed Mendelian randomization (MR) to evaluate the causal relationship between leukocyte telomere length (LTL) and amyotrophic lateral sclerosis (ALS) with summary statistics from genome-wide association studies (n = ~ 38,000 for LTL and ~ 81,000 for ALS in the European population; n = ~ 23,000 for LTL and ~ 4,100 for ALS in the Asian population). We further evaluated mediation roles of lipids in the pathway from LTL to ALS. The odds ratio per standard deviation decrease of LTL on ALS was 1.10 (95% CI 0.93–1.31, p = 0.274) in the European population and 0.75 (95% CI 0.53–1.07, p = 0.116) in the Asian population. This null association was also detected between LTL and frontotemporal dementia in the European population. However, we found that an indirect effect of LTL on ALS might be mediated by low density lipoprotein (LDL) or total cholesterol (TC) in the European population. These results were robust against extensive sensitivity analyses. Overall, our MR study did not support the direct causal association between LTL and the ALS risk in neither population, but provided suggestive evidence for the mediation role of LDL or TC on the influence of LTL and ALS in the European population.
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- Nahar, Khayrun, et al.
(författare)
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Astrocyte-microglial association and matrix composition are common events in the natural history of primary familial brain calcification
- 2020
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Ingår i: Brain Pathology. - : Wiley. - 1015-6305 .- 1750-3639. ; 30:3, s. 446-64
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Tidskriftsartikel (refereegranskat)abstract
- Primary familial brain calcification (PFBC) is an age-dependent and rare neurodegenerative disorder characterized by microvascular calcium phosphate deposits in the deep brain regions. Known genetic causes of PFBC include loss-of-function mutations in genes involved in either of three processes-platelet-derived growth factor (PDGF) signaling, phosphate homeostasis or protein glycosylation-with unclear molecular links. To provide insight into the pathogenesis of PFBC, we analyzed murine models of PFBC for the first two of these processes in Pdgfb(ret/ret) and Slc20a2(-/-) mice with regard to the structure, molecular composition, development and distribution of perivascular calcified nodules. Analyses by transmission electron microscopy and immunofluorescence revealed that calcified nodules in both of these models have a multilayered ultrastructure and occur in direct contact with reactive astrocytes and microglia. However, whereas nodules in Pdgfb(ret/ret) mice were large, solitary and smooth surfaced, the nodules in Slc20a2(-/-) mice were multi-lobulated and occurred in clusters. The regional distribution of nodules also differed between the two models. Proteomic analysis and immunofluorescence stainings revealed a common molecular composition of the nodules in the two models, involving proteins implicated in bone homeostasis, but also proteins not previously linked to tissue mineralization. While the brain vasculature of Pdgfb(ret/ret) mice has been reported to display reduced pericyte coverage and abnormal permeability, we found that Slc20a2(-/-) mice have a normal pericyte coverage and no overtly increased permeability. Thus, lack of pericytes and increase in permeability of the blood-brain barrier are likely not the causal triggers for PFBC pathogenesis. Instead, gene expression and spatial correlations suggest that astrocytes are intimately linked to the calcification process in PFBC.
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| 10. |
- Sun, Y., et al.
(författare)
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An Integrated Bioinformatics Approach for Identifying Genetic Markers that Predict Cerebrospinal Fluid Biomarker p-tau(181)/A beta(1-42) Ratio in ApoE4-Negative Mild Cognitive Impairment Patients
- 2015
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Ingår i: Journal of Alzheimers Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 45:4, s. 1061-1076
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is the most common form of dementia, with no disease-modifying treatment yet available. Early detection of patients at risk of developing AD is of central importance. Blood-based genetic signatures can serve as early detection and as population-based screening tools. In this study, we aimed to identify genetic markers and gene signatures associated with cerebrospinal fluid (CSF) biomarkers levels of t-tau, p-tau(181), and with the two ratios t-tau/ A beta(1-42) and p-tau(181)/A beta(1-42) in the context of progression from mild cognitive impairment (MCI) to AD, and to identify a panel of genetic markers that can predict CSF biomarker p-tau(181)/A beta(1-42) ratio with consideration of APOE epsilon 4 stratification. We analyzed genome-wide the Alzheimer's Disease Neuroimaging Initiative dataset with up to 48 months follow-up. In the first part of the analysis, the main effect of single nucleotide polymorphisms (SNPs) under an additive genetic model was assessed for each of the four CSF biomarkers. In the second part of the analysis, we performed an integrated analysis of genome-wide association study results with pathway enrichment analysis, predictive modeling and network analysis in the subgroup of ApoE4-negative subjects. We identified a panel of five SNPs, rs6766238, rs1143960, rs1249963, rs11975968, and rs4836493, that are predictive for
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