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- Wang, Li-San, et al.
(author)
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Rarity of the Alzheimer Disease-Protective APP A673T Variant in the United States.
- 2015
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In: JAMA neurology. - : American Medical Association (AMA). - 2168-6157 .- 2168-6149. ; 72:2
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Journal article (peer-reviewed)abstract
- Recently, a rare variant in the amyloid precursor protein gene (APP) was described in a population from Iceland. This variant, in which alanine is replaced by threonine at position 673 (A673T), appears to protect against late-onset Alzheimer disease (AD). We evaluated the frequency of this variant in AD cases and cognitively normal controls to determine whether this variant will significantly contribute to risk assessment in individuals in the United States.
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- Guerreiro, R., et al.
(author)
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Heritability and genetic variance of dementia with Lewy bodies
- 2019
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In: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 127, s. 492-501
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Journal article (peer-reviewed)abstract
- Recent large-scale genetic studies have allowed for the first glimpse of the effects of common genetic variability in dementia with Lewy bodies (DLB), identifying risk variants with appreciable effect sizes. However, it is currently well established that a substantial portion of the genetic heritable component of complex traits is not captured by genome-wide significant SNPs. To overcome this issue, we have estimated the proportion of phenotypic variance explained by genetic variability (SNP heritability) in DLB using a method that is unbiased by allele frequency or linkage disequilibrium properties of the underlying variants. This shows that the heritability of DLB is nearly twice as high as previous estimates based on common variants only (31% vs 59.9%). We also determine the amount of phenotypic variance in DLB that can be explained by recent polygenic risk scores from either Parkinson's disease (PD) or Alzheimer's disease (AD), and show that, despite being highly significant, they explain a low amount of variance. Additionally, to identify pleiotropic events that might improve our understanding of the disease, we performed genetic correlation analyses of DLB with over 200 diseases and biomedically relevant traits. Our data shows that DLB has a positive correlation with education phenotypes, which is opposite to what occurs in AD. Overall, our data suggests that novel genetic risk factors for DLB should be identified by larger GWAS and these are likely to be independent from known AD and PD risk variants. © 2019 Elsevier Inc.
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- Guerreiro, R., et al.
(author)
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Investigating the genetic architecture of dementia with Lewy bodies: a two-stage genome-wide association study
- 2018
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In: Lancet Neurology. - 1474-4422. ; 17:1, s. 64-74
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Journal article (peer-reviewed)abstract
- Background Dementia with Lewy bodies is the second most common form of dementia in elderly people but has been overshadowed in the research field, partly because of similarities between dementia with Lewy bodies, Parkinson's disease, and Alzheimer's disease. So far, to our knowledge, no large-scale genetic study of dementia with Lewy bodies has been done. To better understand the genetic basis of dementia with Lewy bodies, we have done a genome-wide association study with the aim of identifying genetic risk factors for this disorder. Methods In this two-stage genome-wide association study, we collected samples from white participants of European ancestry who had been diagnosed with dementia with Lewy bodies according to established clinical or pathological criteria. In the discovery stage (with the case cohort recruited from 22 centres in ten countries and the controls derived from two publicly available database of Genotypes and Phenotypes studies [phs000404.v1.p1 and phs000982.v1.p1] in the USA), we performed genotyping and exploited the recently established Haplotype Reference Consortium panel as the basis for imputation. Pathological samples were ascertained following autopsy in each individual brain bank, whereas clinical samples were collected after participant examination. There was no specific timeframe for collection of samples. We did association analyses in all participants with dementia with Lewy bodies, and also only in participants with pathological diagnosis. In the replication stage, we performed genotyping of significant and suggestive results from the discovery stage. Lastly, we did a meta-analysis of both stages under a fixed-effects model and used logistic regression to test for association in each stage. Findings This study included 1743 patients with dementia with Lewy bodies (1324 with pathological diagnosis) and 4454 controls (1216 patients with dementia with Lewy bodies vs 3791 controls in the discovery stage; 527 vs 663 in the replication stage). Results confirm previously reported associations: APOE (rs429358; odds ratio [OR] 2.40, 95% CI 2.14-2.70; p=1.05 x 10-48), SNCA (rs7681440; OR 0.73, 0.66-0.81; p=6.39 x 10(-10)), and GBA (rs35749011; OR 2.55, 1.88-3.46; p=1.78 x 10(-9)). They also provide some evidence for a novel candidate locus, namely CNTN1 (rs7314908; OR 1.51, 1.27-1.79; p=2.32 x 10(-6)); further replication will be important. Additionally, we estimate the heritable component of dementia with Lewy bodies to be about 36%. Interpretation Despite the small sample size for a genome-wide association study, and acknowledging the potential biases from ascertaining samples from multiple locations, we present the most comprehensive and well powered genetic study in dementia with Lewy bodies so far. These data show that common genetic variability has a role in the disease.
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- Heckbert, Scott, et al.
(author)
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Growing the Precolumbian Maya Social-Ecological System from the Bottom Up
- 2019
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In: The Oxford Handbook of Historical Ecology and Applied Archaeology / edited by Christian Isendahl and Daryl Stump.. - Oxford : Oxford University Press. - 9780199672691 ; , s. 302-322
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Book chapter (peer-reviewed)abstract
- Archaeological data can be represented in quantitative models to test theories of societal growth, development, and resilience. This chapter describes the results of simulations employing integrated agent-based, cellular automata, and network models to represent elements of the ancient Maya social-ecological system. The purpose of the model is to better understand the complex dynamics of the Maya civilization and to test quantitative indicators of resilience as predictors of system sustainability or decline. The model examines the relationship between population growth, agricultural production, pressure on ecosystem services, forest succession, value of trade, and the stability of trade networks. These combine to allow agents representing Maya settlements to develop and expand within a landscape that changes under climate variation and responds to anthropogenic pressure. The model is able to reproduce spatial patterns and timelines somewhat analogous to that of the ancient Maya, although this model requires refinement and further archaeological data for calibration.
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- Phan-Huy, D. -T., et al.
(author)
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Massive Multiple Input Massive Multiple Output for 5G Wireless Backhauling
- 2017
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In: IEEE Globecom Workshops. - 2166-0069. - 9781538639207 ; 2018-January, s. 1-6
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Conference paper (peer-reviewed)abstract
- In this paper, we propose a new technique for the future fifth generation (5G) cellular network wireless backhauling. We show that hundreds of data streams can be spatially multiplexed through a short range and line of sight "massive multiple input massive multiple output" (MMIMMO) propagation channel thanks to a new low complexity spatial multiplexing scheme, called "block discrete Fourier transform based spatial multiplexing with maximum ratio transmission" (B-DFT-SM-MRT). Its performance in real and existing environments is assessed using ray-tracing tools and advanced antenna models. 1.6 kbits/s/Hz of spectral efficiency is attained, corresponding to 80% of Singular Value Decomposition performance, with a transmitter and a receiver that are 200 and 10,000 times less complex, respectively.
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